diff --git a/sql/swh-func.sql b/sql/swh-func.sql
index bba8d4d2..c18389b0 100644
--- a/sql/swh-func.sql
+++ b/sql/swh-func.sql
@@ -1,1279 +1,1279 @@
 -- create a temporary table called tmp_TBLNAME, mimicking existing table
 -- TBLNAME
 --
 -- Args:
 --     tblname: name of the table to mimick
 create or replace function swh_mktemp(tblname regclass)
     returns void
     language plpgsql
 as $$
 begin
     execute format('
 	create temporary table tmp_%1$I
 	    (like %1$I including defaults)
 	    on commit drop;
       alter table tmp_%1$I drop column if exists object_id;
 	', tblname);
     return;
 end
 $$;
 
 -- create a temporary table for directory entries called tmp_TBLNAME,
 -- mimicking existing table TBLNAME with an extra dir_id (sha1_git)
 -- column, and dropping the id column.
 --
 -- This is used to create the tmp_directory_entry_<foo> tables.
 --
 -- Args:
 --     tblname: name of the table to mimick
 create or replace function swh_mktemp_dir_entry(tblname regclass)
     returns void
     language plpgsql
 as $$
 begin
     execute format('
 	create temporary table tmp_%1$I
 	    (like %1$I including defaults, dir_id sha1_git)
 	    on commit drop;
         alter table tmp_%1$I drop column id;
 	', tblname);
     return;
 end
 $$;
 
 
 -- create a temporary table for revisions called tmp_revisions,
 -- mimicking existing table revision, replacing the foreign keys to
 -- people with an email and name field
 --
 create or replace function swh_mktemp_revision()
     returns void
     language sql
 as $$
     create temporary table tmp_revision (
         like revision including defaults,
         author_name bytea not null default '',
         author_email bytea not null default '',
         committer_name bytea not null default '',
         committer_email bytea not null default ''
     ) on commit drop;
     alter table tmp_revision drop column author;
     alter table tmp_revision drop column committer;
     alter table tmp_revision drop column object_id;
 $$;
 
 
 -- create a temporary table for releases called tmp_release,
 -- mimicking existing table release, replacing the foreign keys to
 -- people with an email and name field
 --
 create or replace function swh_mktemp_release()
     returns void
     language sql
 as $$
     create temporary table tmp_release (
         like release including defaults,
         author_name bytea not null default '',
         author_email bytea not null default ''
     ) on commit drop;
     alter table tmp_release drop column author;
     alter table tmp_release drop column object_id;
 $$;
 
 -- create a temporary table with a single "bytea" column for fast object lookup.
 create or replace function swh_mktemp_bytea()
     returns void
     language sql
 as $$
     create temporary table tmp_bytea (
       id bytea
     ) on commit drop;
 $$;
 
 -- create a temporary table for occurrence_history
 create or replace function swh_mktemp_occurrence_history()
     returns void
     language sql
 as $$
     create temporary table tmp_occurrence_history(
         like occurrence_history including defaults,
         date timestamptz not null
     ) on commit drop;
     alter table tmp_occurrence_history
       drop column visits,
       drop column object_id;
 $$;
 
 -- create a temporary table for entity_history, sans id
 create or replace function swh_mktemp_entity_history()
     returns void
     language sql
 as $$
     create temporary table tmp_entity_history (
         like entity_history including defaults) on commit drop;
     alter table tmp_entity_history drop column id;
 $$;
 
 -- create a temporary table for entities called tmp_entity_lister,
 -- with only the columns necessary for retrieving the uuid of a listed
 -- entity.
 create or replace function swh_mktemp_entity_lister()
     returns void
     language sql
 as $$
   create temporary table tmp_entity_lister (
     id              bigint,
     lister_metadata jsonb
   ) on commit drop;
 $$;
 
 -- a content signature is a set of cryptographic checksums that we use to
 -- uniquely identify content, for the purpose of verifying if we already have
 -- some content or not during content injection
 create type content_signature as (
     sha1      sha1,
     sha1_git  sha1_git,
     sha256    sha256
 );
 
 
 -- check which entries of tmp_content are missing from content
 --
 -- operates in bulk: 0. swh_mktemp(content), 1. COPY to tmp_content,
 -- 2. call this function
 create or replace function swh_content_missing()
     returns setof content_signature
     language plpgsql
 as $$
 begin
     -- This query is critical for (single-algorithm) hash collision detection,
     -- so we cannot rely only on the fact that a single hash (e.g., sha1) is
     -- missing from the table content to conclude that a given content is
     -- missing. Ideally, we would want to (try to) add to content all entries
     -- in tmp_content that, when considering all columns together, are missing
     -- from content.
     --
     -- But doing that naively would require a *compound* index on all checksum
     -- columns; that index would not be significantly smaller than the content
     -- table itself, and therefore won't be used. Therefore we union together
     -- all contents that differ on at least one column from what is already
     -- available. If there is a collision on some (but not all) columns, the
     -- relevant tmp_content entry will be included in the set of content to be
     -- added, causing a downstream violation of unicity constraint.
     return query
 	(select sha1, sha1_git, sha256 from tmp_content as tmp
 	 where not exists
 	     (select 1 from content as c where c.sha1 = tmp.sha1))
 	union
 	(select sha1, sha1_git, sha256 from tmp_content as tmp
 	 where not exists
 	     (select 1 from content as c where c.sha1_git = tmp.sha1_git))
 	union
 	(select sha1, sha1_git, sha256 from tmp_content as tmp
 	 where not exists
 	     (select 1 from content as c where c.sha256 = tmp.sha256));
     return;
 end
 $$;
 
 -- check which entries of tmp_content_sha1 are missing from content
 --
 -- operates in bulk: 0. swh_mktemp_content_sha1(), 1. COPY to tmp_content_sha1,
 -- 2. call this function
 create or replace function swh_content_missing_per_sha1()
     returns setof sha1
     language plpgsql
 as $$
 begin
     return query
            (select id::sha1
             from tmp_bytea as tmp
             where not exists
             (select 1 from content as c where c.sha1=tmp.id));
 end
 $$;
 
 
 -- check which entries of tmp_skipped_content are missing from skipped_content
 --
 -- operates in bulk: 0. swh_mktemp(skipped_content), 1. COPY to tmp_skipped_content,
 -- 2. call this function
 create or replace function swh_skipped_content_missing()
     returns setof content_signature
     language plpgsql
 as $$
 begin
     return query
 	select sha1, sha1_git, sha256 from tmp_skipped_content t
 	where not exists
 	(select 1 from skipped_content s where
 	    s.sha1 is not distinct from t.sha1 and
 	    s.sha1_git is not distinct from t.sha1_git and
 	    s.sha256 is not distinct from t.sha256);
     return;
 end
 $$;
 
 
 -- Look up content based on one or several different checksums. Return all
 -- content information if the content is found; a NULL row otherwise.
 --
 -- At least one checksum should be not NULL. If several are not NULL, they will
 -- be AND-ed together in the lookup query.
 --
 -- Note: this function is meant to be used to look up individual contents
 -- (e.g., for the web app), for batch lookup of missing content (e.g., to be
 -- added) see swh_content_missing
 create or replace function swh_content_find(
     sha1      sha1     default NULL,
     sha1_git  sha1_git default NULL,
     sha256    sha256   default NULL
 )
     returns content
     language plpgsql
 as $$
 declare
     con content;
     filters text[] := array[] :: text[];  -- AND-clauses used to filter content
     q text;
 begin
     if sha1 is not null then
         filters := filters || format('sha1 = %L', sha1);
     end if;
     if sha1_git is not null then
         filters := filters || format('sha1_git = %L', sha1_git);
     end if;
     if sha256 is not null then
         filters := filters || format('sha256 = %L', sha256);
     end if;
 
     if cardinality(filters) = 0 then
         return null;
     else
         q = format('select * from content where %s',
 	        array_to_string(filters, ' and '));
         execute q into con;
 	return con;
     end if;
 end
 $$;
 
 
 -- add tmp_content entries to content, skipping duplicates
 --
 -- operates in bulk: 0. swh_mktemp(content), 1. COPY to tmp_content,
 -- 2. call this function
 create or replace function swh_content_add()
     returns void
     language plpgsql
 as $$
 begin
     insert into content (sha1, sha1_git, sha256, length, status)
 	select distinct sha1, sha1_git, sha256, length, status
 	from tmp_content
 	where (sha1, sha1_git, sha256) in
 	    (select * from swh_content_missing());
 	    -- TODO XXX use postgres 9.5 "UPSERT" support here, when available.
 	    -- Specifically, using "INSERT .. ON CONFLICT IGNORE" we can avoid
 	    -- the extra swh_content_missing() query here.
     return;
 end
 $$;
 
 
 -- add tmp_skipped_content entries to skipped_content, skipping duplicates
 --
 -- operates in bulk: 0. swh_mktemp(skipped_content), 1. COPY to tmp_skipped_content,
 -- 2. call this function
 create or replace function swh_skipped_content_add()
     returns void
     language plpgsql
 as $$
 begin
     insert into skipped_content (sha1, sha1_git, sha256, length, status, reason, origin)
 	select distinct sha1, sha1_git, sha256, length, status, reason, origin
 	from tmp_skipped_content
 	where (coalesce(sha1, ''), coalesce(sha1_git, ''), coalesce(sha256, '')) in
 	    (select coalesce(sha1, ''), coalesce(sha1_git, ''), coalesce(sha256, '') from swh_skipped_content_missing());
 	    -- TODO XXX use postgres 9.5 "UPSERT" support here, when available.
 	    -- Specifically, using "INSERT .. ON CONFLICT IGNORE" we can avoid
 	    -- the extra swh_content_missing() query here.
     return;
 end
 $$;
 
 
 -- check which entries of tmp_directory are missing from directory
 --
 -- operates in bulk: 0. swh_mktemp(directory), 1. COPY to tmp_directory,
 -- 2. call this function
 create or replace function swh_directory_missing()
     returns setof sha1_git
     language plpgsql
 as $$
 begin
     return query
 	select id from tmp_directory t
 	where not exists (
 	    select 1 from directory d
 	    where d.id = t.id);
     return;
 end
 $$;
 
 
 -- Retrieve information on directory from temporary table
 create or replace function swh_directory_get()
     returns setof directory
     language plpgsql
 as $$
 begin
     return query
 	select d.*
         from tmp_directory t
         inner join directory d on t.id = d.id;
     return;
 end
 $$;
 
 
 create type directory_entry_type as enum('file', 'dir', 'rev');
 
 
 -- Add tmp_directory_entry_* entries to directory_entry_* and directory,
 -- skipping duplicates in directory_entry_*.  This is a generic function that
 -- works on all kind of directory entries.
 --
 -- operates in bulk: 0. swh_mktemp_dir_entry('directory_entry_*'), 1 COPY to
 -- tmp_directory_entry_*, 2. call this function
 --
 -- Assumption: this function is used in the same transaction that inserts the
 -- context directory in table "directory".
 create or replace function swh_directory_entry_add(typ directory_entry_type)
     returns void
     language plpgsql
 as $$
 begin
     execute format('
     insert into directory_entry_%1$s (target, name, perms)
     select distinct t.target, t.name, t.perms
     from tmp_directory_entry_%1$s t
     where not exists (
     select 1
     from directory_entry_%1$s i
     where t.target = i.target and t.name = i.name and t.perms = i.perms)
    ', typ);
 
     execute format('
     with new_entries as (
 	select t.dir_id, array_agg(i.id) as entries
 	from tmp_directory_entry_%1$s t
 	inner join directory_entry_%1$s i
 	using (target, name, perms)
 	group by t.dir_id
     )
     update tmp_directory as d
     set %1$s_entries = new_entries.entries
     from new_entries
     where d.id = new_entries.dir_id
     ', typ);
 
     return;
 end
 $$;
 
 -- Insert the data from tmp_directory, tmp_directory_entry_file,
 -- tmp_directory_entry_dir, tmp_directory_entry_rev into their final
 -- tables.
 --
 -- Prerequisites:
 --  directory ids in tmp_directory
 --  entries in tmp_directory_entry_{file,dir,rev}
 --
 create or replace function swh_directory_add()
     returns void
     language plpgsql
 as $$
 begin
     perform swh_directory_entry_add('file');
     perform swh_directory_entry_add('dir');
     perform swh_directory_entry_add('rev');
 
     insert into directory
     select * from tmp_directory t
     where not exists (
         select 1 from directory d
 	where d.id = t.id);
 
     return;
 end
 $$;
 
 -- a directory listing entry with all the metadata
 --
 -- can be used to list a directory, and retrieve all the data in one go.
 create type directory_entry as
 (
   dir_id   sha1_git,     -- id of the parent directory
   type     directory_entry_type,  -- type of entry
   target   sha1_git,     -- id of target
   name     unix_path,    -- path name, relative to containing dir
   perms    file_perms,   -- unix-like permissions
   status   content_status,  -- visible or absent
   sha1     sha1,            -- content if sha1 if type is not dir
   sha1_git sha1_git,        -- content's sha1 git if type is not dir
   sha256   sha256           -- content's sha256 if type is not dir
 );
 
 
 -- List a single level of directory walked_dir_id
 -- FIXME: order by name is not correct. For git, we need to order by
 -- lexicographic order but as if a trailing / is present in directory
 -- name
 create or replace function swh_directory_walk_one(walked_dir_id sha1_git)
     returns setof directory_entry
     language sql
     stable
 as $$
     with dir as (
 	select id as dir_id, dir_entries, file_entries, rev_entries
 	from directory
 	where id = walked_dir_id),
     ls_d as (select dir_id, unnest(dir_entries) as entry_id from dir),
     ls_f as (select dir_id, unnest(file_entries) as entry_id from dir),
     ls_r as (select dir_id, unnest(rev_entries) as entry_id from dir)
     (select dir_id, 'dir'::directory_entry_type as type,
             e.target, e.name, e.perms, NULL::content_status,
             NULL::sha1, NULL::sha1_git, NULL::sha256
      from ls_d
      left join directory_entry_dir e on ls_d.entry_id = e.id)
     union
     (select dir_id, 'file'::directory_entry_type as type,
             e.target, e.name, e.perms, c.status,
             c.sha1, c.sha1_git, c.sha256
      from ls_f
      left join directory_entry_file e on ls_f.entry_id = e.id
      left join content c on e.target = c.sha1_git)
     union
     (select dir_id, 'rev'::directory_entry_type as type,
             e.target, e.name, e.perms, NULL::content_status,
             NULL::sha1, NULL::sha1_git, NULL::sha256
      from ls_r
      left join directory_entry_rev e on ls_r.entry_id = e.id)
     order by name;
 $$;
 
 -- List recursively the content of a directory
 create or replace function swh_directory_walk(walked_dir_id sha1_git)
     returns setof directory_entry
     language sql
     stable
 as $$
     with recursive entries as (
         select dir_id, type, target, name, perms, status, sha1, sha1_git,
                sha256
         from swh_directory_walk_one(walked_dir_id)
         union all
         select dir_id, type, target, (dirname || '/' || name)::unix_path as name,
                perms, status, sha1, sha1_git, sha256
         from (select (swh_directory_walk_one(dirs.target)).*, dirs.name as dirname
               from (select target, name from entries where type = 'dir') as dirs) as with_parent
     )
     select dir_id, type, target, name, perms, status, sha1, sha1_git, sha256
     from entries
 $$;
 
 -- Find a directory entry by its path
 create or replace function swh_find_directory_entry_by_path(
     walked_dir_id sha1_git,
     dir_or_content_path bytea[])
     returns directory_entry
     language plpgsql
 as $$
 declare
     end_index integer;
     paths bytea default '';
     path bytea;
     res bytea[];
     r record;
 begin
     end_index := array_upper(dir_or_content_path, 1);
     res[1] := walked_dir_id;
 
     for i in 1..end_index
     loop
         path := dir_or_content_path[i];
         -- concatenate path for patching the name in the result record (if we found it)
         if i = 1 then
             paths = path;
         else
             paths := paths || '/' || path;  -- concatenate paths
         end if;
 
         if i <> end_index then
             select *
             from swh_directory_walk_one(res[i] :: sha1_git)
             where name=path
             and type = 'dir'
             limit 1 into r;
         else
             select *
             from swh_directory_walk_one(res[i] :: sha1_git)
             where name=path
             limit 1 into r;
         end if;
 
         -- find the path
         if r is null then
            return null;
         else
             -- store the next dir to lookup the next local path from
             res[i+1] := r.target;
         end if;
     end loop;
 
     -- at this moment, r is the result. Patch its 'name' with the full path before returning it.
     r.name := paths;
     return r;
 end
 $$;
 
 -- List all revision IDs starting from a given revision, going back in time
 --
 -- TODO ordering: should be breadth-first right now (what do we want?)
 -- TODO ordering: ORDER BY parent_rank somewhere?
 create or replace function swh_revision_list(root_revisions bytea[], num_revs bigint default NULL)
     returns table (id sha1_git, parents bytea[])
     language sql
     stable
 as $$
     with recursive full_rev_list(id) as (
         (select id from revision where id = ANY(root_revisions))
         union
         (select h.parent_id
          from revision_history as h
          join full_rev_list on h.id = full_rev_list.id)
     ),
     rev_list as (select id from full_rev_list limit num_revs)
     select rev_list.id as id,
            array(select rh.parent_id::bytea
                  from revision_history rh
                  where rh.id = rev_list.id
                  order by rh.parent_rank
                 ) as parent
     from rev_list;
 $$;
 
 -- List all the children of a given revision
 create or replace function swh_revision_list_children(root_revisions bytea[], num_revs bigint default NULL)
     returns table (id sha1_git, parents bytea[])
     language sql
     stable
 as $$
     with recursive full_rev_list(id) as (
         (select id from revision where id = ANY(root_revisions))
         union
         (select h.id
          from revision_history as h
          join full_rev_list on h.parent_id = full_rev_list.id)
     ),
     rev_list as (select id from full_rev_list limit num_revs)
     select rev_list.id as id,
            array(select rh.parent_id::bytea
                  from revision_history rh
                  where rh.id = rev_list.id
                  order by rh.parent_rank
                 ) as parent
     from rev_list;
 $$;
 
 
 -- Detailed entry for a revision
 create type revision_entry as
 (
   id                     sha1_git,
   date                   timestamptz,
   date_offset            smallint,
   date_neg_utc_offset    boolean,
   committer_date         timestamptz,
   committer_date_offset  smallint,
   committer_date_neg_utc_offset    boolean,
   type                   revision_type,
   directory              sha1_git,
   message                bytea,
   author_id              bigint,
   author_name            bytea,
   author_email           bytea,
   committer_id           bigint,
   committer_name         bytea,
   committer_email        bytea,
   metadata               jsonb,
   synthetic              boolean,
   parents                bytea[]
 );
 
 
 -- "git style" revision log. Similar to swh_revision_list(), but returning all
 -- information associated to each revision, and expanding authors/committers
 create or replace function swh_revision_log(root_revisions bytea[], num_revs bigint default NULL)
     returns setof revision_entry
     language sql
     stable
 as $$
     select t.id, r.date, r.date_offset, r.date_neg_utc_offset,
            r.committer_date, r.committer_date_offset, r.committer_date_neg_utc_offset,
            r.type, r.directory, r.message,
            a.id, a.name, a.email,
            c.id, c.name, c.email,
            r.metadata, r.synthetic, t.parents
     from swh_revision_list(root_revisions, num_revs) as t
     left join revision r on t.id = r.id
     left join person a on a.id = r.author
     left join person c on c.id = r.committer;
 $$;
 
 
--- Retrieve revisions from tmp_revision in bulk
+-- Retrieve revisions from tmp_bytea in bulk
 create or replace function swh_revision_get()
     returns setof revision_entry
     language plpgsql
 as $$
 begin
     return query
-        select t.id, r.date, r.date_offset, r.date_neg_utc_offset,
+        select r.id, r.date, r.date_offset, r.date_neg_utc_offset,
                r.committer_date, r.committer_date_offset, r.committer_date_neg_utc_offset,
                r.type, r.directory, r.message,
                a.id, a.name, a.email, c.id, c.name, c.email, r.metadata, r.synthetic,
          array(select rh.parent_id::bytea from revision_history rh where rh.id = t.id order by rh.parent_rank)
                    as parents
-        from tmp_revision t
+        from tmp_bytea t
         left join revision r on t.id = r.id
         left join person a on a.id = r.author
         left join person c on c.id = r.committer;
     return;
 end
 $$;
 
--- List missing revisions from tmp_revision
+-- List missing revisions from tmp_bytea
 create or replace function swh_revision_missing()
     returns setof sha1_git
     language plpgsql
 as $$
 begin
     return query
-        select id from tmp_revision t
+        select id::sha1_git from tmp_bytea t
 	where not exists (
 	    select 1 from revision r
 	    where r.id = t.id);
     return;
 end
 $$;
 
 -- Detailed entry for a release
 create type release_entry as
 (
   id           sha1_git,
   target       sha1_git,
   target_type  object_type,
   date         timestamptz,
   date_offset  smallint,
   date_neg_utc_offset boolean,
   name         bytea,
   comment      bytea,
   synthetic    boolean,
   author_id    bigint,
   author_name  bytea,
   author_email bytea
 );
 
 -- Detailed entry for release
 create or replace function swh_release_get()
     returns setof release_entry
     language plpgsql
 as $$
 begin
     return query
         select r.id, r.target, r.target_type, r.date, r.date_offset, r.date_neg_utc_offset, r.name, r.comment,
                r.synthetic, p.id as author_id, p.name as author_name, p.email as author_email
         from tmp_bytea t
         inner join release r on t.id = r.id
         inner join person p on p.id = r.author;
     return;
 end
 $$;
 
 -- Create entries in person from tmp_revision
 create or replace function swh_person_add_from_revision()
     returns void
     language plpgsql
 as $$
 begin
     with t as (
         select author_name as name, author_email as email from tmp_revision
     union
         select committer_name as name, committer_email as email from tmp_revision
     ) insert into person (name, email)
     select distinct name, email from t
     where not exists (
         select 1
 	from person p
 	where t.name = p.name and t.email = p.email
     );
     return;
 end
 $$;
 
 
 -- Create entries in revision from tmp_revision
 create or replace function swh_revision_add()
     returns void
     language plpgsql
 as $$
 begin
     perform swh_person_add_from_revision();
 
     insert into revision (id, date, date_offset, date_neg_utc_offset, committer_date, committer_date_offset, committer_date_neg_utc_offset, type, directory, message, author, committer, metadata, synthetic)
     select t.id, t.date, t.date_offset, t.date_neg_utc_offset, t.committer_date, t.committer_date_offset, t.committer_date_neg_utc_offset, t.type, t.directory, t.message, a.id, c.id, t.metadata, t.synthetic
     from tmp_revision t
     left join person a on a.name = t.author_name and a.email = t.author_email
     left join person c on c.name = t.committer_name and c.email = t.committer_email;
     return;
 end
 $$;
 
 
 -- List missing releases from tmp_bytea
 create or replace function swh_release_missing()
     returns setof sha1_git
     language plpgsql
 as $$
 begin
   return query
     select id::sha1_git from tmp_bytea t
     where not exists (
       select 1 from release r
       where r.id = t.id);
 end
 $$;
 
 
 -- Create entries in person from tmp_release
 create or replace function swh_person_add_from_release()
     returns void
     language plpgsql
 as $$
 begin
     with t as (
         select distinct author_name as name, author_email as email from tmp_release
     ) insert into person (name, email)
     select name, email from t
     where not exists (
         select 1
 	from person p
 	where t.name = p.name and t.email = p.email
     );
     return;
 end
 $$;
 
 
 -- Create entries in release from tmp_release
 create or replace function swh_release_add()
     returns void
     language plpgsql
 as $$
 begin
     perform swh_person_add_from_release();
 
     insert into release (id, target, target_type, date, date_offset, date_neg_utc_offset, name, comment, author, synthetic)
     select t.id, t.target, t.target_type, t.date, t.date_offset, t.date_neg_utc_offset, t.name, t.comment, a.id, t.synthetic
     from tmp_release t
     left join person a on a.name = t.author_name and a.email = t.author_email;
     return;
 end
 $$;
 
 create or replace function swh_occurrence_update_for_origin(origin_id bigint)
   returns void
   language sql
 as $$
   delete from occurrence where origin = origin_id;
   insert into occurrence (origin, branch, target, target_type)
     select origin, branch, target, target_type
     from occurrence_history
     where origin = origin_id and
           (select visit from origin_visit
            where origin = origin_id
            order by date desc
            limit 1) = any(visits);
 $$;
 
 create or replace function swh_occurrence_update_all()
   returns void
   language plpgsql
 as $$
 declare
   origin_id origin.id%type;
 begin
   for origin_id in
     select distinct id from origin
   loop
     perform swh_occurrence_update_for_origin(origin_id);
   end loop;
   return;
 end;
 $$;
 
 
 
 -- add tmp_occurrence_history entries to occurrence_history
 --
 -- operates in bulk: 0. swh_mktemp(occurrence_history), 1. COPY to tmp_occurrence_history,
 -- 2. call this function
 create or replace function swh_occurrence_history_add()
     returns void
     language plpgsql
 as $$
 declare
   origin_id origin.id%type;
 begin
   -- Create new visits
   with current_visits as (
     select distinct origin, date from tmp_occurrence_history
   ),
   new_visits as (
       select origin, date, (select coalesce(max(visit), 0)
                             from origin_visit ov
                             where ov.origin = cv.origin) as max_visit
         from current_visits cv
         where not exists (select 1 from origin_visit ov
                           where ov.origin = cv.origin and
                                 ov.date = cv.date)
   )
   insert into origin_visit (origin, date, visit)
     select origin, date, max_visit + row_number() over
                                      (partition by origin
                                                 order by origin, date)
     from new_visits;
 
   -- Create or update occurrence_history
   with occurrence_history_id_visit as (
     select tmp_occurrence_history.*, object_id, visits, visit from tmp_occurrence_history
     left join occurrence_history using(origin, branch, target, target_type)
     left join origin_visit using(origin, date)
   ),
   occurrences_to_update as (
     select object_id, visit from occurrence_history_id_visit where object_id is not null
   ),
   update_occurrences as (
     update occurrence_history
     set visits = array(select unnest(occurrence_history.visits) as e
                         union
                        select occurrences_to_update.visit as e
                        order by e)
     from occurrences_to_update
     where occurrence_history.object_id = occurrences_to_update.object_id
   )
   insert into occurrence_history (origin, branch, target, target_type, visits)
     select origin, branch, target, target_type, ARRAY[visit]
       from occurrence_history_id_visit
       where object_id is null;
 
   -- update occurrence
   for origin_id in
     select distinct origin from tmp_occurrence_history
   loop
     perform swh_occurrence_update_for_origin(origin_id);
   end loop;
   return;
 end
 $$;
 
 
 -- Absolute path: directory reference + complete path relative to it
 create type content_dir as (
     directory  sha1_git,
     path       unix_path
 );
 
 
 -- Find the containing directory of a given content, specified by sha1
 -- (note: *not* sha1_git).
 --
 -- Return a pair (dir_it, path) where path is a UNIX path that, from the
 -- directory root, reach down to a file with the desired content. Return NULL
 -- if no match is found.
 --
 -- In case of multiple paths (i.e., pretty much always), an arbitrary one is
 -- chosen.
 create or replace function swh_content_find_directory(content_id sha1)
     returns content_dir
     language sql
     stable
 as $$
     with recursive path as (
 	-- Recursively build a path from the requested content to a root
 	-- directory. Each iteration returns a pair (dir_id, filename) where
 	-- filename is relative to dir_id. Stops when no parent directory can
 	-- be found.
 	(select dir.id as dir_id, dir_entry_f.name as name, 0 as depth
 	 from directory_entry_file as dir_entry_f
 	 join content on content.sha1_git = dir_entry_f.target
 	 join directory as dir on dir.file_entries @> array[dir_entry_f.id]
 	 where content.sha1 = content_id
 	 limit 1)
 	union all
 	(select dir.id as dir_id,
 		(dir_entry_d.name || '/' || path.name)::unix_path as name,
 		path.depth + 1
 	 from path
 	 join directory_entry_dir as dir_entry_d on dir_entry_d.target = path.dir_id
 	 join directory as dir on dir.dir_entries @> array[dir_entry_d.id]
 	 limit 1)
     )
     select dir_id, name from path order by depth desc limit 1;
 $$;
 
 
 -- Walk the revision history starting from a given revision, until a matching
 -- occurrence is found. Return all occurrence information if one is found, NULL
 -- otherwise.
 create or replace function swh_revision_find_occurrence(revision_id sha1_git)
     returns occurrence
     language sql
     stable
 as $$
 	select origin, branch, target, target_type
   from swh_revision_list_children(ARRAY[revision_id] :: bytea[]) as rev_list
 	left join occurrence_history occ_hist
   on rev_list.id = occ_hist.target
 	where occ_hist.origin is not null and
         occ_hist.target_type = 'revision'
 	limit 1;
 $$;
 
 -- Find the visit of origin id closest to date visit_date
 create or replace function swh_visit_find_by_date(origin bigint, visit_date timestamptz default NOW())
     returns origin_visit
     language sql
     stable
 as $$
   with closest_two_visits as ((
     select origin_visit, (date - visit_date) as interval
     from origin_visit
     where date >= visit_date
     order by date asc
     limit 1
   ) union (
     select origin_visit, (visit_date - date) as interval
     from origin_visit
     where date < visit_date
     order by date desc
     limit 1
   )) select (origin_visit).* from closest_two_visits order by interval limit 1
 $$;
 
 
 -- Retrieve occurrence by filtering on origin_id and optionally on
 -- branch_name and/or validity range
 create or replace function swh_occurrence_get_by(
        origin_id bigint,
        branch_name bytea default NULL,
        date timestamptz default NULL)
     returns setof occurrence_history
     language plpgsql
 as $$
 declare
     filters text[] := array[] :: text[];  -- AND-clauses used to filter content
     visit_id bigint;
     q text;
 begin
     if origin_id is not null then
         filters := filters || format('origin = %L', origin_id);
     end if;
     if branch_name is not null then
         filters := filters || format('branch = %L', branch_name);
     end if;
     if date is not null then
         if origin_id is null then
             raise exception 'Needs an origin_id to filter by date.';
         end if;
         select visit from swh_visit_find_by_date(origin_id, date) into visit_id;
         if visit_id is null then
             return;
         end if;
         filters := filters || format('%L = any(visits)', visit_id);
     end if;
 
     if cardinality(filters) = 0 then
         raise exception 'At least one filter amongst (origin_id, branch_name, date) is needed';
     else
         q = format('select * ' ||
                    'from occurrence_history ' ||
                    'where %s',
 	        array_to_string(filters, ' and '));
         return query execute q;
     end if;
 end
 $$;
 
 
 -- Retrieve revisions by occurrence criterion filtering
 create or replace function swh_revision_get_by(
        origin_id bigint,
        branch_name bytea default NULL,
        date timestamptz default NULL)
     returns setof revision_entry
     language sql
     stable
 as $$
     select r.id, r.date, r.date_offset, r.date_neg_utc_offset,
         r.committer_date, r.committer_date_offset, r.committer_date_neg_utc_offset,
         r.type, r.directory, r.message,
         a.id, a.name, a.email, c.id, c.name, c.email, r.metadata, r.synthetic,
         array(select rh.parent_id::bytea
             from revision_history rh
             where rh.id = r.id
             order by rh.parent_rank
         ) as parents
     from swh_occurrence_get_by(origin_id, branch_name, date) as occ
     inner join revision r on occ.target = r.id
     left join person a on a.id = r.author
     left join person c on c.id = r.committer;
 $$;
 
 -- Retrieve a release by occurrence criterion
 create or replace function swh_release_get_by(
        origin_id bigint)
     returns setof release_entry
     language sql
     stable
 as $$
    select r.id, r.target, r.target_type, r.date, r.date_offset, r.date_neg_utc_offset,
         r.name, r.comment, r.synthetic, a.id as author_id,
         a.name as author_name, a.email as author_email
     from release r
     inner join occurrence_history occ on occ.target = r.target
     left join person a on a.id = r.author
     where occ.origin = origin_id and occ.target_type = 'revision' and r.target_type = 'revision';
 $$;
 
 
 -- Occurrence of some content in a given context
 create type content_occurrence as (
     origin_type	 text,
     origin_url	 text,
     branch	 bytea,
     target	 sha1_git,
     target_type	 object_type,
     path	 unix_path
 );
 
 
 -- Given the sha1 of some content, look up an occurrence that points to a
 -- revision, which in turns reference (transitively) a tree containing the
 -- content. Answer the question: "where/when did SWH see a given content"?
 -- Return information about an arbitrary occurrence/revision/tree if one is
 -- found, NULL otherwise.
 create or replace function swh_content_find_occurrence(content_id sha1)
     returns content_occurrence
     language plpgsql
 as $$
 declare
     dir content_dir;
     rev sha1_git;
     occ occurrence%ROWTYPE;
     coc content_occurrence;
 begin
     -- each step could fail if no results are found, and that's OK
     select * from swh_content_find_directory(content_id)     -- look up directory
 	into dir;
     if not found then return null; end if;
 
     select id from revision where directory = dir.directory  -- look up revision
 	limit 1
 	into rev;
     if not found then return null; end if;
 
     select * from swh_revision_find_occurrence(rev)	     -- look up occurrence
 	into occ;
     if not found then return null; end if;
 
     select origin.type, origin.url, occ.branch, occ.target, occ.target_type, dir.path
     from origin
     where origin.id = occ.origin
     into coc;
 
     return coc;  -- might be NULL
 end
 $$;
 
 create type object_found as (
     sha1_git   sha1_git,
     type       object_type,
     id         bytea,       -- sha1 or sha1_git depending on object_type
     object_id  bigint
 );
 
 -- Find objects by sha1_git, return their type and their main identifier
 create or replace function swh_object_find_by_sha1_git()
     returns setof object_found
     language plpgsql
 as $$
 begin
     return query
     with known_objects as ((
         select id as sha1_git, 'release'::object_type as type, id, object_id from release r
         where exists (select 1 from tmp_bytea t where t.id = r.id)
     ) union all (
         select id as sha1_git, 'revision'::object_type as type, id, object_id from revision r
         where exists (select 1 from tmp_bytea t where t.id = r.id)
     ) union all (
         select id as sha1_git, 'directory'::object_type as type, id, object_id from directory d
         where exists (select 1 from tmp_bytea t where t.id = d.id)
     ) union all (
         select sha1_git as sha1_git, 'content'::object_type as type, sha1 as id, object_id from content c
         where exists (select 1 from tmp_bytea t where t.id = c.sha1_git)
     ))
     select t.id::sha1_git as sha1_git, k.type, k.id, k.object_id from tmp_bytea t
       left join known_objects k on t.id = k.sha1_git;
 end
 $$;
 
 -- Create entries in entity_history from tmp_entity_history
 --
 -- TODO: do something smarter to compress the entries if the data
 -- didn't change.
 create or replace function swh_entity_history_add()
     returns void
     language plpgsql
 as $$
 begin
     insert into entity_history (
         uuid, parent, name, type, description, homepage, active, generated, lister_metadata, metadata, validity
     ) select * from tmp_entity_history;
     return;
 end
 $$;
 
 
 create or replace function swh_update_entity_from_entity_history()
     returns trigger
     language plpgsql
 as $$
 begin
     insert into entity (uuid, parent, name, type, description, homepage, active, generated,
       lister_metadata, metadata, last_seen, last_id)
       select uuid, parent, name, type, description, homepage, active, generated,
              lister_metadata, metadata, unnest(validity), id
       from entity_history
       where uuid = NEW.uuid
       order by unnest(validity) desc limit 1
     on conflict (uuid) do update set
       parent = EXCLUDED.parent,
       name = EXCLUDED.name,
       type = EXCLUDED.type,
       description = EXCLUDED.description,
       homepage = EXCLUDED.homepage,
       active = EXCLUDED.active,
       generated = EXCLUDED.generated,
       lister_metadata = EXCLUDED.lister_metadata,
       metadata = EXCLUDED.metadata,
       last_seen = EXCLUDED.last_seen,
       last_id = EXCLUDED.last_id;
 
     return null;
 end
 $$;
 
 create trigger update_entity
   after insert or update
   on entity_history
   for each row
   execute procedure swh_update_entity_from_entity_history();
 
 -- map an id of tmp_entity_lister to a full entity
 create type entity_id as (
     id               bigint,
     uuid             uuid,
     parent           uuid,
     name             text,
     type             entity_type,
     description      text,
     homepage         text,
     active           boolean,
     generated        boolean,
     lister_metadata  jsonb,
     metadata         jsonb,
     last_seen        timestamptz,
     last_id          bigint
 );
 
 -- find out the uuid of the entries of entity with the metadata
 -- contained in tmp_entity_lister
 create or replace function swh_entity_from_tmp_entity_lister()
     returns setof entity_id
     language plpgsql
 as $$
 begin
   return query
     select t.id, e.*
     from tmp_entity_lister t
     left join entity e
     on e.lister_metadata @> t.lister_metadata;
   return;
 end
 $$;
 
 create or replace function swh_entity_get(entity_uuid uuid)
     returns setof entity
     language sql
     stable
 as $$
   with recursive entity_hierarchy as (
   select e.*
     from entity e where uuid = entity_uuid
     union
     select p.*
     from entity_hierarchy e
     join entity p on e.parent = p.uuid
   )
   select *
   from entity_hierarchy;
 $$;
 
 -- simple counter mapping a textual label to an integer value
 create type counter as (
     label  text,
     value  bigint
 );
 
 -- return statistics about the number of tuples in various SWH tables
 --
 -- Note: the returned values are based on postgres internal statistics
 -- (pg_class table), which are only updated daily (by autovacuum) or so
 create or replace function swh_stat_counters()
     returns setof counter
     language sql
     stable
 as $$
     select relname::text as label, reltuples::bigint as value
     from pg_class
     where oid in (
         'public.content'::regclass,
         'public.directory'::regclass,
         'public.directory_entry_dir'::regclass,
         'public.directory_entry_file'::regclass,
         'public.directory_entry_rev'::regclass,
         'public.occurrence'::regclass,
         'public.occurrence_history'::regclass,
         'public.origin'::regclass,
         'public.person'::regclass,
         'public.entity'::regclass,
         'public.entity_history'::regclass,
         'public.release'::regclass,
         'public.revision'::regclass,
         'public.revision_history'::regclass,
         'public.skipped_content'::regclass
     );
 $$;
diff --git a/sql/swh-schema.sql b/sql/swh-schema.sql
index 8749482d..26abf71a 100644
--- a/sql/swh-schema.sql
+++ b/sql/swh-schema.sql
@@ -1,424 +1,424 @@
 ---
 --- Software Heritage Data Model
 ---
 
 -- drop schema if exists swh cascade;
 -- create schema swh;
 -- set search_path to swh;
 
 create table dbversion
 (
   version     int primary key,
   release     timestamptz,
   description text
 );
 
 insert into dbversion(version, release, description)
-      values(66, now(), 'Work In Progress');
+      values(67, now(), 'Work In Progress');
 
 -- a SHA1 checksum (not necessarily originating from Git)
 create domain sha1 as bytea check (length(value) = 20);
 
 -- a Git object ID, i.e., a SHA1 checksum
 create domain sha1_git as bytea check (length(value) = 20);
 
 -- a SHA256 checksum
 create domain sha256 as bytea check (length(value) = 32);
 
 -- UNIX path (absolute, relative, individual path component, etc.)
 create domain unix_path as bytea;
 
 -- a set of UNIX-like access permissions, as manipulated by, e.g., chmod
 create domain file_perms as int;
 
 create type content_status as enum ('absent', 'visible', 'hidden');
 
 -- Checksums about actual file content. Note that the content itself is not
 -- stored in the DB, but on external (key-value) storage. A single checksum is
 -- used as key there, but the other can be used to verify that we do not inject
 -- content collisions not knowingly.
 create table content
 (
   sha1      sha1 primary key,
   sha1_git  sha1_git not null,
   sha256    sha256 not null,
   length    bigint not null,
   ctime     timestamptz not null default now(),
             -- creation time, i.e. time of (first) injection into the storage
   status    content_status not null default 'visible',
   object_id bigserial
 );
 
 create unique index on content(sha1_git);
 create unique index on content(sha256);
 create index on content(ctime);  -- TODO use a BRIN index here (postgres >= 9.5)
 
 -- Entities constitute a typed hierarchy of organization, hosting
 -- facilities, groups, people and software projects.
 --
 -- Examples of entities: Software Heritage, Debian, GNU, GitHub,
 -- Apache, The Linux Foundation, the Debian Python Modules Team, the
 -- torvalds GitHub user, the torvalds/linux GitHub project.
 --
 -- The data model is hierarchical (via the parent attribute) and might
 -- store sub-branches of existing entities. The key feature of an
 -- entity is might be *listed* (if it is available in listable_entity)
 -- to retrieve information about its content, i.e: sub-entities,
 -- projects, origins.
 
 -- Types of entities.
 --
 -- - organization: a root entity, usually backed by a non-profit, a
 -- company, or another kind of "association". (examples: Software
 -- Heritage, Debian, GNU, GitHub)
 --
 -- - group_of_entities: used for hierarchies, doesn't need to have a
 -- concrete existence. (examples: GNU hosting facilities, Debian
 -- hosting facilities, GitHub users, ...)
 --
 -- - hosting: a hosting facility, can usually be listed to generate
 -- other data. (examples: GitHub git hosting, alioth.debian.org,
 -- snapshot.debian.org)
 --
 -- - group_of_persons: an entity representing a group of
 -- persons. (examples: a GitHub organization, a Debian team)
 --
 -- - person: an entity representing a person. (examples:
 -- a GitHub user, a Debian developer)
 --
 -- - project: an entity representing a software project. (examples: a
 -- GitHub project, Apache httpd, a Debian source package, ...)
 create type entity_type as enum (
   'organization',
   'group_of_entities',
   'hosting',
   'group_of_persons',
   'person',
   'project'
 );
 
 -- The history of entities. Allows us to keep historical metadata
 -- about entities.  The temporal invariant is the uuid. Root
 -- organization uuids are manually generated (and available in
 -- swh-data.sql).
 --
 -- For generated entities (generated = true), we can provide
 -- generation_metadata to allow listers to retrieve the uuids of previous
 -- iterations of the entity.
 --
 -- Inactive entities that have been active in the past (active =
 -- false) should register the timestamp at which we saw them
 -- deactivate, in a new entry of entity_history.
 create table entity_history
 (
   id               bigserial primary key,
   uuid             uuid,
   parent           uuid,             -- should reference entity_history(uuid)
   name             text not null,
   type             entity_type not null,
   description      text,
   homepage         text,
   active           boolean not null, -- whether the entity was seen on the last listing
   generated        boolean not null, -- whether this entity has been generated by a lister
   lister_metadata  jsonb,            -- lister-specific metadata, used for queries
   metadata         jsonb,
   validity         timestamptz[]     -- timestamps at which we have seen this entity
 );
 
 create index on entity_history(uuid);
 create index on entity_history(name);
 
 -- The entity table provides a view of the latest information on a
 -- given entity. It is updated via a trigger on entity_history.
 create table entity
 (
   uuid             uuid primary key,
   parent           uuid references entity(uuid) deferrable initially deferred,
   name             text not null,
   type             entity_type not null,
   description      text,
   homepage         text,
   active           boolean not null, -- whether the entity was seen on the last listing
   generated        boolean not null, -- whether this entity has been generated by a lister
   lister_metadata  jsonb,            -- lister-specific metadata, used for queries
   metadata         jsonb,
   last_seen        timestamptz,      -- last listing time or disappearance time for active=false
   last_id          bigint references entity_history(id) -- last listing id
 );
 
 create index on entity(name);
 create index on entity using gin(lister_metadata jsonb_path_ops);
 
 -- Register the equivalence between two entities. Allows sideways
 -- navigation in the entity table
 create table entity_equivalence
 (
   entity1 uuid references entity(uuid),
   entity2 uuid references entity(uuid),
   primary key (entity1, entity2),
   constraint order_entities check (entity1 < entity2)
 );
 
 -- Register a lister for a specific entity.
 create table listable_entity
 (
   uuid         uuid references entity(uuid) primary key,
   enabled      boolean not null default true, -- do we list this entity automatically?
   list_engine  text,  -- crawler to be used to list entity's content
   list_url     text,  -- root URL to start the listing
   list_params  jsonb,  -- org-specific listing parameter
   latest_list  timestamptz  -- last time the entity's content has been listed
 );
 
 -- Log of all entity listings (i.e., entity crawling) that have been
 -- done in the past, or are still ongoing.
 create table list_history
 (
   id        bigserial primary key,
   entity    uuid references listable_entity(uuid),
   date      timestamptz not null,
   status    boolean,  -- true if and only if the listing has been successful
   result    jsonb,     -- more detailed return value, depending on status
   stdout    text,
   stderr    text,
   duration  interval  -- fetch duration of NULL if still ongoing
 );
 
 
 -- An origin is a place, identified by an URL, where software can be found. We
 -- support different kinds of origins, e.g., git and other VCS repositories,
 -- web pages that list tarballs URLs (e.g., http://www.kernel.org), indirect
 -- tarball URLs (e.g., http://www.example.org/latest.tar.gz), etc. The key
 -- feature of an origin is that it can be *fetched* (wget, git clone, svn
 -- checkout, etc.) to retrieve all the contained software.
 create table origin
 (
   id       bigserial primary key,
   type     text, -- TODO use an enum here (?)
   url      text not null,
   lister   uuid references listable_entity(uuid),
   project  uuid references entity(uuid)
 );
 
 create index on origin(type, url);
 
 -- Content we have seen but skipped for some reason. This table is
 -- separate from the content table as we might not have the sha1
 -- checksum of that data (for instance when we inject git
 -- repositories, objects that are too big will be skipped here, and we
 -- will only know their sha1_git). 'reason' contains the reason the
 -- content was skipped. origin is a nullable column allowing to find
 -- out which origin contains that skipped content.
 create table skipped_content
 (
   sha1      sha1,
   sha1_git  sha1_git,
   sha256    sha256,
   length    bigint not null,
   ctime     timestamptz not null default now(),
   status    content_status not null default 'absent',
   reason    text not null,
   origin    bigint references origin(id),
   object_id bigserial,
   unique (sha1, sha1_git, sha256)
 );
 
 -- those indexes support multiple NULL values.
 create unique index on skipped_content(sha1);
 create unique index on skipped_content(sha1_git);
 create unique index on skipped_content(sha256);
 
 
 -- Log of all origin fetches (i.e., origin crawling) that have been done in the
 -- past, or are still ongoing. Similar to list_history, but for origins.
 create table fetch_history
 (
   id        bigserial primary key,
   origin    bigint references origin(id),
   date      timestamptz not null,
   status    boolean,  -- true if and only if the fetch has been successful
   result    jsonb,     -- more detailed returned values, times, etc...
   stdout    text,
   stderr    text,     -- null when status is true, filled otherwise
   duration  interval  -- fetch duration of NULL if still ongoing
 );
 
 
 -- A file-system directory.  A directory is a list of directory entries (see
 -- tables: directory_entry_{dir,file}).
 --
 -- To list the contents of a directory:
 -- 1. list the contained directory_entry_dir using array dir_entries
 -- 2. list the contained directory_entry_file using array file_entries
 -- 3. list the contained directory_entry_rev using array rev_entries
 -- 4. UNION
 --
 -- Synonyms/mappings:
 -- * git: tree
 create table directory
 (
   id            sha1_git primary key,
   dir_entries   bigint[],  -- sub-directories, reference directory_entry_dir
   file_entries  bigint[],  -- contained files, reference directory_entry_file
   rev_entries   bigint[],  -- mounted revisions, reference directory_entry_rev
   object_id     bigserial  -- short object identifier
 );
 
 create index on directory using gin (dir_entries);
 create index on directory using gin (file_entries);
 create index on directory using gin (rev_entries);
 
 -- A directory entry pointing to a sub-directory.
 create table directory_entry_dir
 (
   id      bigserial primary key,
   target  sha1_git,   -- id of target directory
   name    unix_path,  -- path name, relative to containing dir
   perms   file_perms  -- unix-like permissions
 );
 
 create unique index on directory_entry_dir(target, name, perms);
 
 -- A directory entry pointing to a file.
 create table directory_entry_file
 (
   id      bigserial primary key,
   target  sha1_git,   -- id of target file
   name    unix_path,  -- path name, relative to containing dir
   perms   file_perms  -- unix-like permissions
 );
 
 create unique index on directory_entry_file(target, name, perms);
 
 -- A directory entry pointing to a revision.
 create table directory_entry_rev
 (
   id      bigserial primary key,
   target  sha1_git,   -- id of target revision
   name    unix_path,  -- path name, relative to containing dir
   perms   file_perms  -- unix-like permissions
 );
 
 create unique index on directory_entry_rev(target, name, perms);
 
 create table person
 (
   id     bigserial primary key,
   name   bytea not null default '',
   email  bytea not null default ''
 );
 
 create unique index on person(name, email);
 
 create type revision_type as enum ('git', 'tar', 'dsc', 'svn');
 
 -- the data object types stored in our data model
 create type object_type as enum ('content', 'directory', 'revision', 'release');
 
 -- A snapshot of a software project at a specific point in time.
 --
 -- Synonyms/mappings:
 -- * git / subversion / etc: commit
 -- * tarball: a specific tarball
 --
 -- Revisions are organized as DAGs. Each revision points to 0, 1, or more (in
 -- case of merges) parent revisions. Each revision points to a directory, i.e.,
 -- a file-system tree containing files and directories.
 create table revision
 (
   id                    sha1_git primary key,
   date                  timestamptz,
   date_offset           smallint,
   date_neg_utc_offset   boolean,
   committer_date        timestamptz,
   committer_date_offset smallint,
   committer_date_neg_utc_offset boolean,
   type                  revision_type not null,
   directory             sha1_git,  -- file-system tree
   message               bytea,
   author                bigint references person(id),
   committer             bigint references person(id),
   metadata              jsonb, -- extra metadata (tarball checksums, extra commit information, etc...)
   synthetic             boolean not null default false,  -- true if synthetic (cf. swh-loader-tar)
   object_id             bigserial
 );
 
 create index on revision(directory);
 
 -- either this table or the sha1_git[] column on the revision table
 create table revision_history
 (
   id           sha1_git references revision(id),
   parent_id    sha1_git,
   parent_rank  int not null default 0,
     -- parent position in merge commits, 0-based
   primary key (id, parent_rank)
 );
 
 create index on revision_history(parent_id);
 
 -- The timestamps at which Software Heritage has made a visit of the given origin.
 create table origin_visit
 (
   origin  bigint not null references origin(id),
   visit   bigint not null,
   date    timestamptz not null,
   primary key (origin, visit)
 );
 
 create index on origin_visit(date);
 
 -- The content of software origins is indexed starting from top-level pointers
 -- called "branches". Every time we fetch some origin we store in this table
 -- where the branches pointed to at fetch time.
 --
 -- Synonyms/mappings:
 -- * git: ref (in the "git update-ref" sense)
 create table occurrence_history
 (
   origin       bigint references origin(id) not null,
   branch       bytea not null,        -- e.g., b"master" (for VCS), or b"sid" (for Debian)
   target       sha1_git not null,     -- ref target, e.g., commit id
   target_type  object_type not null,  -- ref target type
   object_id    bigserial not null,    -- short object identifier
   visits       bigint[] not null,     -- the visits where that occurrence was valid. References
                                       -- origin_visit(visit), where o_h.origin = origin_visit.origin.
   primary key (object_id)
 );
 
 create index on occurrence_history(target, target_type);
 create index on occurrence_history(origin, branch);
 create unique index on occurrence_history(origin, branch, target, target_type);
 
 -- Materialized view of occurrence_history, storing the *current* value of each
 -- branch, as last seen by SWH.
 create table occurrence
 (
   origin    bigint references origin(id) not null,
   branch    bytea not null,
   target    sha1_git not null,
   target_type object_type not null,
   primary key(origin, branch)
 );
 
 -- A "memorable" point in the development history of a project.
 --
 -- Synonyms/mappings:
 -- * git: tag (of the annotated kind, otherwise they are just references)
 -- * tarball: the release version number
 create table release
 (
   id          sha1_git primary key,
   target      sha1_git,
   target_type object_type,
   date        timestamptz,
   date_offset smallint,
   date_neg_utc_offset  boolean,
   name        bytea,
   comment     bytea,
   author      bigint references person(id),
   synthetic   boolean not null default false,  -- true if synthetic (cf. swh-loader-tar)
   object_id   bigserial
 );
 
 create index on release(target, target_type);
diff --git a/sql/upgrades/067.sql b/sql/upgrades/067.sql
new file mode 100644
index 00000000..a4dce40d
--- /dev/null
+++ b/sql/upgrades/067.sql
@@ -0,0 +1,39 @@
+-- SWH DB schema upgrade
+-- from_version: 66
+-- to_version: 67
+-- description: use tmp_bytea instead of tmp_revision to retrieve revision info
+
+insert into dbversion(version, release, description)
+      values(67, now(), 'Work In Progress');
+
+CREATE OR REPLACE FUNCTION swh_revision_get() RETURNS SETOF revision_entry
+    LANGUAGE plpgsql
+    AS $$
+begin
+    return query
+        select r.id, r.date, r.date_offset, r.date_neg_utc_offset,
+               r.committer_date, r.committer_date_offset, r.committer_date_neg_utc_offset,
+               r.type, r.directory, r.message,
+               a.id, a.name, a.email, c.id, c.name, c.email, r.metadata, r.synthetic,
+         array(select rh.parent_id::bytea from revision_history rh where rh.id = t.id order by rh.parent_rank)
+                   as parents
+        from tmp_bytea t
+        left join revision r on t.id = r.id
+        left join person a on a.id = r.author
+        left join person c on c.id = r.committer;
+    return;
+end
+$$;
+
+CREATE OR REPLACE FUNCTION swh_revision_missing() RETURNS SETOF sha1_git
+    LANGUAGE plpgsql
+    AS $$
+begin
+    return query
+        select id::sha1_git from tmp_bytea t
+	where not exists (
+	    select 1 from revision r
+	    where r.id = t.id);
+    return;
+end
+$$;
diff --git a/swh/storage/api/client.py b/swh/storage/api/client.py
index cdc39957..937d7f6a 100644
--- a/swh/storage/api/client.py
+++ b/swh/storage/api/client.py
@@ -1,200 +1,199 @@
 # Copyright (C) 2015  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 import pickle
 
 import requests
 
 from requests.exceptions import ConnectionError
 from swh.core.serializers import msgpack_dumps, msgpack_loads, SWHJSONDecoder
 from swh.storage.exc import StorageAPIError
 
 
 def encode_data(data):
     try:
         return msgpack_dumps(data)
     except OverflowError as e:
         raise ValueError('Limits were reached. Please, check your input.\n' +
                          str(e))
 
 
 def decode_response(response):
     content_type = response.headers['content-type']
 
     if content_type.startswith('application/x-msgpack'):
         r = msgpack_loads(response.content)
     elif content_type.startswith('application/json'):
         r = response.json(cls=SWHJSONDecoder)
     else:
         raise ValueError('Wrong content type `%s` for API response'
                          % content_type)
 
     return r
 
 
 class RemoteStorage():
     """Proxy to a remote storage API"""
     def __init__(self, base_url):
         self.base_url = base_url
         self.session = requests.Session()
 
     def url(self, endpoint):
         return '%s%s' % (self.base_url, endpoint)
 
     def post(self, endpoint, data):
         try:
             response = self.session.post(
                 self.url(endpoint),
                 data=encode_data(data),
                 headers={'content-type': 'application/x-msgpack'},
             )
         except ConnectionError as e:
             print(str(e))
             raise StorageAPIError(e)
 
         # XXX: this breaks language-independence and should be
         # replaced by proper unserialization
         if response.status_code == 400:
             raise pickle.loads(decode_response(response))
 
         return decode_response(response)
 
     def get(self, endpoint, data=None):
         try:
             response = self.session.get(
                 self.url(endpoint),
                 params=data,
             )
         except ConnectionError as e:
             print(str(e))
             raise StorageAPIError(e)
 
         if response.status_code == 404:
             return None
 
         # XXX: this breaks language-independence and should be
         # replaced by proper unserialization
         if response.status_code == 400:
             raise pickle.loads(decode_response(response))
 
         else:
             return decode_response(response)
 
     def content_add(self, content):
         return self.post('content/add', {'content': content})
 
     def content_missing(self, content, key_hash='sha1'):
         return self.post('content/missing', {'content': content,
                                              'key_hash': key_hash})
 
     def content_missing_per_sha1(self, contents):
         return self.post('content/missing/sha1', {'contents': contents})
 
     def content_get(self, content):
         return self.post('content/data', {'content': content})
 
     def content_find(self, content):
         return self.post('content/present', {'content': content})
 
     def content_find_occurrence(self, content):
         return self.post('content/occurrence', {'content': content})
 
     def directory_add(self, directories):
         return self.post('directory/add', {'directories': directories})
 
     def directory_missing(self, directories):
         return self.post('directory/missing', {'directories': directories})
 
     def directory_get(self, directories):
         return self.post('directory', dict(directories=directories))
 
     def directory_ls(self, directory, recursive=False):
         return self.get('directory/ls', {'directory': directory,
                                          'recursive': recursive})
 
     def revision_get(self, revisions):
         return self.post('revision', {'revisions': revisions})
 
     def revision_get_by(self, origin_id, branch_name, timestamp, limit=None):
         return self.post('revision/by', dict(origin_id=origin_id,
                                              branch_name=branch_name,
                                              timestamp=timestamp,
                                              limit=limit))
 
     def revision_log(self, revisions, limit=None):
         return self.post('revision/log', {'revisions': revisions,
                                           'limit': limit})
 
     def revision_shortlog(self, revisions, limit=None):
         return self.post('revision/shortlog', {'revisions': revisions,
                                                'limit': limit})
 
     def revision_add(self, revisions):
         return self.post('revision/add', {'revisions': revisions})
 
-    def revision_missing(self, revisions, type='git'):
-        return self.post('revision/missing', {'revisions': revisions,
-                                              'type': type})
+    def revision_missing(self, revisions):
+        return self.post('revision/missing', {'revisions': revisions})
 
     def release_add(self, releases):
         return self.post('release/add', {'releases': releases})
 
     def release_get(self, releases):
         return self.post('release', {'releases': releases})
 
     def release_get_by(self, origin_id, limit=None):
         return self.post('release/by', dict(origin_id=origin_id,
                                             limit=limit))
 
     def release_missing(self, releases):
         return self.post('release/missing', {'releases': releases})
 
     def object_find_by_sha1_git(self, ids):
         return self.post('object/find_by_sha1_git', {'ids': ids})
 
     def occurrence_get(self, origin_id):
         return self.post('occurrence', {'origin_id': origin_id})
 
     def occurrence_add(self, occurrences):
         return self.post('occurrence/add', {'occurrences': occurrences})
 
     def origin_get(self, origin):
         return self.post('origin/get', {'origin': origin})
 
     def origin_add_one(self, origin):
         return self.post('origin/add', {'origin': origin})
 
     def person_get(self, person):
         return self.post('person', {'person': person})
 
     def fetch_history_start(self, origin_id):
         return self.post('fetch_history/start', {'origin_id': origin_id})
 
     def fetch_history_end(self, fetch_history_id, data):
         return self.post('fetch_history/end',
                          {'fetch_history_id': fetch_history_id,
                           'data': data})
 
     def fetch_history_get(self, fetch_history_id):
         return self.get('fetch_history', {'id': fetch_history_id})
 
     def entity_add(self, entities):
         return self.post('entity/add', {'entities': entities})
 
     def entity_get(self, uuid):
         return self.post('entity/get', {'uuid': uuid})
 
     def entity_get_one(self, uuid):
         return self.get('entity', {'uuid': uuid})
 
     def entity_get_from_lister_metadata(self, entities):
         return self.post('entity/from_lister_metadata', {'entities': entities})
 
     def stat_counters(self):
         return self.get('stat/counters')
 
     def directory_entry_get_by_path(self, directory, paths):
         return self.post('directory/path', dict(directory=directory,
                                                 paths=paths))
diff --git a/swh/storage/storage.py b/swh/storage/storage.py
index f91117d4..93dd7261 100644
--- a/swh/storage/storage.py
+++ b/swh/storage/storage.py
@@ -1,1123 +1,1111 @@
 # Copyright (C) 2015  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 
 from collections import defaultdict
 import datetime
 import functools
 import itertools
 import dateutil.parser
 import psycopg2
 
 from . import converters
 from .db import Db
 from .objstorage import ObjStorage
 from .exc import ObjNotFoundError, StorageDBError
 
 from swh.core.hashutil import ALGORITHMS
 
 # Max block size of contents to return
 BULK_BLOCK_CONTENT_LEN_MAX = 10000
 
 
 def db_transaction(meth):
     """decorator to execute Storage methods within DB transactions
 
     The decorated method must accept a `cur` keyword argument
     """
     @functools.wraps(meth)
     def _meth(self, *args, **kwargs):
         with self.db.transaction() as cur:
             return meth(self, *args, cur=cur, **kwargs)
     return _meth
 
 
 def db_transaction_generator(meth):
     """decorator to execute Storage methods within DB transactions, while
     returning a generator
 
     The decorated method must accept a `cur` keyword argument
 
     """
     @functools.wraps(meth)
     def _meth(self, *args, **kwargs):
         with self.db.transaction() as cur:
             yield from meth(self, *args, cur=cur, **kwargs)
     return _meth
 
 
 class Storage():
     """SWH storage proxy, encompassing DB and object storage
 
     """
 
     def __init__(self, db_conn, obj_root):
         """
         Args:
             db_conn: either a libpq connection string, or a psycopg2 connection
             obj_root: path to the root of the object storage
 
         """
         try:
             if isinstance(db_conn, psycopg2.extensions.connection):
                 self.db = Db(db_conn)
             else:
                 self.db = Db.connect(db_conn)
         except psycopg2.OperationalError as e:
             raise StorageDBError(e)
 
         self.objstorage = ObjStorage(obj_root)
 
     def content_add(self, content):
         """Add content blobs to the storage
 
         Note: in case of DB errors, objects might have already been added to
         the object storage and will not be removed. Since addition to the
         object storage is idempotent, that should not be a problem.
 
         Args:
             content: iterable of dictionaries representing individual pieces of
                 content to add. Each dictionary has the following keys:
                 - data (bytes): the actual content
                 - length (int): content length (default: -1)
                 - one key for each checksum algorithm in
                   swh.core.hashutil.ALGORITHMS, mapped to the corresponding
                   checksum
                 - status (str): one of visible, hidden, absent
                 - reason (str): if status = absent, the reason why
                 - origin (int): if status = absent, the origin we saw the
                   content in
 
         """
         db = self.db
 
         content_by_status = defaultdict(list)
         for d in content:
             if 'status' not in d:
                 d['status'] = 'visible'
             if 'length' not in d:
                 d['length'] = -1
             content_by_status[d['status']].append(d)
 
         content_with_data = content_by_status['visible']
         content_without_data = content_by_status['absent']
 
         missing_content = set(self.content_missing(content_with_data))
         missing_skipped = set(
             sha1_git for sha1, sha1_git, sha256
             in self.skipped_content_missing(content_without_data))
 
         with db.transaction() as cur:
             if missing_content:
                 # create temporary table for metadata injection
                 db.mktemp('content', cur)
 
                 def add_to_objstorage(cont):
                     self.objstorage.add_bytes(cont['data'],
                                               obj_id=cont['sha1'])
 
                 content_filtered = (cont for cont in content_with_data
                                     if cont['sha1'] in missing_content)
 
                 db.copy_to(content_filtered, 'tmp_content',
                            ['sha1', 'sha1_git', 'sha256', 'length', 'status'],
                            cur, item_cb=add_to_objstorage)
 
                 # move metadata in place
                 db.content_add_from_temp(cur)
 
             if missing_skipped:
                 missing_filtered = (cont for cont in content_without_data
                                     if cont['sha1_git'] in missing_skipped)
                 db.mktemp('skipped_content', cur)
                 db.copy_to(missing_filtered, 'tmp_skipped_content',
                            ['sha1', 'sha1_git', 'sha256', 'length',
                             'reason', 'status', 'origin'], cur)
 
                 # move metadata in place
                 db.skipped_content_add_from_temp(cur)
 
     def content_get(self, content):
         """Retrieve in bulk contents and their data.
 
         Args:
             content: iterables of sha1
 
         Returns:
             Generates streams of contents as dict with their raw data:
             - sha1: sha1's content
             - data: bytes data of the content
 
         Raises:
             ValueError in case of too much contents are required.
             cf. BULK_BLOCK_CONTENT_LEN_MAX
 
         """
         # FIXME: Improve on server module to slice the result
         if len(content) > BULK_BLOCK_CONTENT_LEN_MAX:
             raise ValueError(
                 "Send at maximum %s contents." % BULK_BLOCK_CONTENT_LEN_MAX)
 
         for obj_id in content:
             try:
                 data = self.objstorage.get_bytes(obj_id)
             except ObjNotFoundError:
                 yield None
                 continue
 
             yield {'sha1': obj_id, 'data': data}
 
     @db_transaction_generator
     def content_missing(self, content, key_hash='sha1', cur=None):
         """List content missing from storage
 
         Args:
             content: iterable of dictionaries containing one key for each
                 checksum algorithm in swh.core.hashutil.ALGORITHMS, mapped to
                 the corresponding checksum, and a length key mapped to the
                 content length.
             key_hash: the name of the hash used as key (default: 'sha1')
 
         Returns:
             an iterable of `key_hash`es missing from the storage
 
         Raises:
             TODO: an exception when we get a hash collision.
 
         """
         db = self.db
 
         keys = ['sha1', 'sha1_git', 'sha256']
 
         if key_hash not in keys:
             raise ValueError("key_hash should be one of %s" % keys)
 
         key_hash_idx = keys.index(key_hash)
 
         # Create temporary table for metadata injection
         db.mktemp('content', cur)
 
         db.copy_to(content, 'tmp_content', keys + ['length'], cur)
 
         for obj in db.content_missing_from_temp(cur):
             yield obj[key_hash_idx]
 
     @db_transaction_generator
     def content_missing_per_sha1(self, contents, cur=None):
         """List content missing from storage based only on sha1.
 
         Args:
             contents: Iterable of sha1 to check for absence.
 
         Returns:
             an iterable of `sha1`s missing from the storage.
 
         Raises:
             TODO: an exception when we get a hash collision.
 
         """
         db = self.db
 
         db.store_tmp_bytea(contents, cur)
         for obj in db.content_missing_per_sha1_from_temp(cur):
             yield obj[0]
 
     @db_transaction_generator
     def skipped_content_missing(self, content, cur=None):
         """List skipped_content missing from storage
 
         Args:
             content: iterable of dictionaries containing the data for each
                 checksum algorithm.
 
         Returns:
             an iterable of signatures missing from the storage
         """
         keys = ['sha1', 'sha1_git', 'sha256']
 
         db = self.db
 
         db.mktemp('skipped_content', cur)
         db.copy_to(content, 'tmp_skipped_content',
                    keys + ['length', 'reason'], cur)
 
         yield from db.skipped_content_missing_from_temp(cur)
 
     @db_transaction
     def content_find(self, content, cur=None):
         """Find a content hash in db.
 
         Args:
             content: a dictionary representing one content hash, mapping
                 checksum algorithm names (see swh.core.hashutil.ALGORITHMS) to
                 checksum values
 
         Returns:
             a triplet (sha1, sha1_git, sha256) if the content exist
             or None otherwise.
 
         Raises:
             ValueError in case the key of the dictionary is not sha1, sha1_git
             nor sha256.
 
         """
         db = self.db
 
         if not set(content).intersection(ALGORITHMS):
             raise ValueError('content keys must contain at least one of: '
                              'sha1, sha1_git, sha256')
 
         c = db.content_find(sha1=content.get('sha1'),
                             sha1_git=content.get('sha1_git'),
                             sha256=content.get('sha256'),
                             cur=cur)
         if c:
             keys = ['sha1', 'sha1_git', 'sha256', 'length', 'ctime', 'status']
             return dict(zip(keys, c))
         return None
 
     @db_transaction
     def content_find_occurrence(self, content, cur=None):
         """Find the content's occurrence.
 
         Args:
             content: a dictionary entry representing one content hash.
             The dictionary key is one of swh.core.hashutil.ALGORITHMS.
             The value mapped to the corresponding checksum.
 
         Returns:
             The occurrence of the content.
 
         Raises:
             ValueError in case the key of the dictionary is not sha1, sha1_git
             nor sha256.
 
         """
         db = self.db
 
         c = self.content_find(content)
 
         if not c:
             return None
 
         sha1 = c['sha1']
 
         found_occ = db.content_find_occurrence(sha1, cur=cur)
         if found_occ:
             keys = ['origin_type', 'origin_url', 'branch', 'target',
                     'target_type', 'path']
             return dict(zip(keys, found_occ))
         return None
 
     def directory_add(self, directories):
         """Add directories to the storage
 
         Args:
             directories: iterable of dictionaries representing the individual
                 directories to add. Each dict has the following keys:
                 - id (sha1_git): the id of the directory to add
                 - entries (list): list of dicts for each entry in the
                     directory.  Each dict has the following keys:
                     - name (bytes)
                     - type (one of 'file', 'dir', 'rev'):
                         type of the directory entry (file, directory, revision)
                     - target (sha1_git): id of the object pointed at by the
                           directory entry
                     - perms (int): entry permissions
         """
         dirs = set()
         dir_entries = {
             'file': defaultdict(list),
             'dir': defaultdict(list),
             'rev': defaultdict(list),
         }
 
         for cur_dir in directories:
             dir_id = cur_dir['id']
             dirs.add(dir_id)
             for src_entry in cur_dir['entries']:
                 entry = src_entry.copy()
                 entry['dir_id'] = dir_id
                 dir_entries[entry['type']][dir_id].append(entry)
 
         dirs_missing = set(self.directory_missing(dirs))
         if not dirs_missing:
             return
 
         db = self.db
         with db.transaction() as cur:
             # Copy directory ids
             dirs_missing_dict = ({'id': dir} for dir in dirs_missing)
             db.mktemp('directory', cur)
             db.copy_to(dirs_missing_dict, 'tmp_directory', ['id'], cur)
 
             # Copy entries
             for entry_type, entry_list in dir_entries.items():
                 entries = itertools.chain.from_iterable(
                     entries_for_dir
                     for dir_id, entries_for_dir
                     in entry_list.items()
                     if dir_id in dirs_missing)
 
                 db.mktemp_dir_entry(entry_type)
 
                 db.copy_to(
                     entries,
                     'tmp_directory_entry_%s' % entry_type,
                     ['target', 'name', 'perms', 'dir_id'],
                     cur,
                 )
 
             # Do the final copy
             db.directory_add_from_temp(cur)
 
     @db_transaction_generator
     def directory_missing(self, directories, cur):
         """List directories missing from storage
 
         Args: an iterable of directory ids
         Returns: a list of missing directory ids
         """
         db = self.db
 
         # Create temporary table for metadata injection
         db.mktemp('directory', cur)
 
         directories_dicts = ({'id': dir} for dir in directories)
 
         db.copy_to(directories_dicts, 'tmp_directory', ['id'], cur)
 
         for obj in db.directory_missing_from_temp(cur):
             yield obj[0]
 
     @db_transaction_generator
     def directory_get(self,
                       directories,
                       cur=None):
         """Get information on directories.
 
         Args:
             - directories: an iterable of directory ids
 
         Returns:
             List of directories as dict with keys and associated values.
 
         """
         db = self.db
         keys = ('id', 'dir_entries', 'file_entries', 'rev_entries')
 
         db.mktemp('directory', cur)
         db.copy_to(({'id': dir_id} for dir_id in directories),
                    'tmp_directory', ['id'], cur)
 
         dirs = db.directory_get_from_temp(cur)
         for line in dirs:
             yield dict(zip(keys, line))
 
     @db_transaction_generator
     def directory_ls(self, directory, recursive=False, cur=None):
         """Get entries for one directory.
 
         Args:
             - directory: the directory to list entries from.
             - recursive: if flag on, this list recursively from this directory.
 
         Returns:
             List of entries for such directory.
 
         """
         db = self.db
         keys = ['dir_id', 'type', 'target', 'name', 'perms', 'status',
                 'sha1', 'sha1_git', 'sha256']
 
         if recursive:
             res_gen = db.directory_walk(directory)
         else:
             res_gen = db.directory_walk_one(directory)
 
         for line in res_gen:
             yield dict(zip(keys, line))
 
     @db_transaction
     def directory_entry_get_by_path(self, directory, paths, cur=None):
         """Get the directory entry (either file or dir) from directory with
         path.
 
         Args:
             - directory: sha1 of the top level directory
             - paths: path to lookup from the top level directory. From left
             (top) to right (bottom).
 
         Returns:
             The corresponding directory entry if found, None otherwise.
 
         """
         db = self.db
         keys = ('dir_id', 'type', 'target', 'name', 'perms', 'status',
                 'sha1', 'sha1_git', 'sha256')
 
         res = db.directory_entry_get_by_path(directory, paths, cur)
         if res:
             return dict(zip(keys, res))
 
     def revision_add(self, revisions):
         """Add revisions to the storage
 
         Args:
             revisions: iterable of dictionaries representing the individual
                 revisions to add. Each dict has the following keys:
                 - id (sha1_git): id of the revision to add
                 - date (datetime.DateTime): date the revision was written
                 - date_offset (int): offset from UTC in minutes the revision
                     was written
                 - date_neg_utc_offset (boolean): whether a null date_offset
                     represents a negative UTC offset
                 - committer_date (datetime.DateTime): date the revision got
                     added to the origin
                 - committer_date_offset (int): offset from UTC in minutes the
                     revision was added to the origin
                 - committer_date_neg_utc_offset (boolean): whether a null
                     committer_date_offset represents a negative UTC offset
                 - type (one of 'git', 'tar'): type of the revision added
                 - directory (sha1_git): the directory the revision points at
                 - message (bytes): the message associated with the revision
                 - author_name (bytes): the name of the revision author
                 - author_email (bytes): the email of the revision author
                 - committer_name (bytes): the name of the revision committer
                 - committer_email (bytes): the email of the revision committer
                 - metadata (jsonb): extra information as dictionary
                 - synthetic (bool): revision's nature (tarball, directory
                     creates synthetic revision)
                 - parents (list of sha1_git): the parents of this revision
         """
         db = self.db
 
         revisions_missing = set(self.revision_missing(
             set(revision['id'] for revision in revisions)))
 
         if not revisions_missing:
             return
 
         with db.transaction() as cur:
             db.mktemp_revision(cur)
 
             revisions_filtered = (
                 converters.revision_to_db(revision) for revision in revisions
                 if revision['id'] in revisions_missing)
 
             parents_filtered = []
 
             db.copy_to(
                 revisions_filtered, 'tmp_revision',
                 ['id', 'date', 'date_offset', 'date_neg_utc_offset',
                  'committer_date', 'committer_date_offset',
                  'committer_date_neg_utc_offset', 'type', 'directory',
                  'message', 'author_name', 'author_email', 'committer_name',
                  'committer_email', 'metadata', 'synthetic'],
                 cur,
                 lambda rev: parents_filtered.extend(rev['parents']))
 
             db.revision_add_from_temp(cur)
 
             db.copy_to(parents_filtered, 'revision_history',
                        ['id', 'parent_id', 'parent_rank'], cur)
 
     @db_transaction_generator
-    def revision_missing(self, revisions, type='git', cur=None):
+    def revision_missing(self, revisions, cur=None):
         """List revisions missing from storage
 
-        Args:
-            - revisions: an iterable of revision ids
-            - type: revision's type (git by default)
+        Args: an iterable of revision ids
 
         Returns: a list of missing revision ids
         """
         db = self.db
 
-        # Create temporary table for metadata injection
-        db.mktemp('revision', cur)
-
-        revisions_dicts = ({'id': dir, 'type': type} for dir in revisions)
-
-        db.copy_to(revisions_dicts, 'tmp_revision', ['id', 'type'], cur)
+        db.store_tmp_bytea(revisions, cur)
 
         for obj in db.revision_missing_from_temp(cur):
             yield obj[0]
 
     @db_transaction_generator
     def revision_get(self, revisions, cur):
         """Get all revisions from storage
            Args: an iterable of revision ids
            Returns: an iterable of revisions as dictionaries
                     (or None if the revision doesn't exist)
         """
 
         keys = ('id', 'date', 'date_offset', 'date_neg_utc_offset',
                 'committer_date', 'committer_date_offset',
                 'committer_date_neg_utc_offset', 'type', 'directory',
                 'message', 'author_id', 'author_name', 'author_email',
                 'committer_id', 'committer_name', 'committer_email',
                 'metadata', 'synthetic', 'parents')
 
         db = self.db
 
-        # Create temporary table for metadata injection
-        db.mktemp('revision', cur)
-
-        revisions_dicts = ({'id': rev, 'type': 'git'} for rev in revisions)
-
-        db.copy_to(revisions_dicts, 'tmp_revision', ['id', 'type'], cur)
+        db.store_tmp_bytea(revisions, cur)
 
         for line in self.db.revision_get_from_temp(cur):
             data = converters.db_to_revision(dict(zip(keys, line)))
             if not data['type']:
                 yield None
                 continue
             yield data
 
     @db_transaction_generator
     def revision_log(self, revisions, limit=None, cur=None):
         """Fetch revision entry from the given root revisions.
 
         Args:
             - revisions: array of root revision to lookup
             - limit: limitation on the output result. Default to null.
 
         Yields:
             List of revision log from such revisions root.
 
         """
         db = self.db
 
         keys = ['id', 'date', 'date_offset', 'date_neg_utc_offset',
                 'committer_date', 'committer_date_offset',
                 'committer_date_neg_utc_offset', 'type', 'directory',
                 'message', 'author_id', 'author_name', 'author_email',
                 'committer_id', 'committer_name', 'committer_email',
                 'metadata', 'synthetic', 'parents']
 
         for line in db.revision_log(revisions, limit, cur):
             data = converters.db_to_revision(dict(zip(keys, line)))
             if not data['type']:
                 yield None
                 continue
             yield data
 
     @db_transaction_generator
     def revision_shortlog(self, revisions, limit=None, cur=None):
         """Fetch the shortlog for the given revisions
 
         Args:
             revisions: list of root revisions to lookup
             limit: depth limitation for the output
 
         Yields:
             a list of (id, parents) tuples.
         """
 
         db = self.db
 
         yield from db.revision_shortlog(revisions, limit, cur)
 
     @db_transaction_generator
     def revision_log_by(self, origin_id, limit=None, cur=None):
         """Fetch revision entry from the actual origin_id's latest revision.
 
         """
         db = self.db
 
         keys = ('id', 'date', 'date_offset', 'date_neg_utc_offset',
                 'committer_date', 'committer_date_offset',
                 'committer_date_neg_utc_offset', 'type', 'directory',
                 'message', 'author_id', 'author_name', 'author_email',
                 'committer_id', 'committer_name', 'committer_email',
                 'metadata', 'synthetic', 'parents')
 
         for line in db.revision_log_by(origin_id, limit, cur):
             data = converters.db_to_revision(dict(zip(keys, line)))
             if not data['type']:
                 yield None
                 continue
             yield data
 
     def release_add(self, releases):
         """Add releases to the storage
 
         Args:
             releases: iterable of dictionaries representing the individual
                 releases to add. Each dict has the following keys:
                 - id (sha1_git): id of the release to add
                 - revision (sha1_git): id of the revision the release points
                     to
                 - date (datetime.DateTime): the date the release was made
                 - date_offset (int): offset from UTC in minutes the release was
                     made
                 - date_neg_utc_offset (boolean): whether a null date_offset
                     represents a negative UTC offset
                 - name (bytes): the name of the release
                 - comment (bytes): the comment associated with the release
                 - author_name (bytes): the name of the release author
                 - author_email (bytes): the email of the release author
         """
         db = self.db
 
         release_ids = set(release['id'] for release in releases)
         releases_missing = set(self.release_missing(release_ids))
 
         if not releases_missing:
             return
 
         with db.transaction() as cur:
             db.mktemp_release(cur)
 
             releases_filtered = (
                 converters.release_to_db(release) for release in releases
                 if release['id'] in releases_missing
             )
 
             db.copy_to(releases_filtered, 'tmp_release',
                        ['id', 'target', 'target_type', 'date', 'date_offset',
                         'date_neg_utc_offset', 'name', 'comment',
                         'author_name', 'author_email', 'synthetic'],
                        cur)
 
             db.release_add_from_temp(cur)
 
     @db_transaction_generator
     def release_missing(self, releases, cur=None):
         """List releases missing from storage
 
         Args: an iterable of release ids
         Returns: a list of missing release ids
         """
         db = self.db
 
         # Create temporary table for metadata injection
         db.store_tmp_bytea(releases, cur)
 
         for obj in db.release_missing_from_temp(cur):
             yield obj[0]
 
     @db_transaction_generator
     def release_get(self, releases, cur=None):
         """Given a list of sha1, return the releases's information
 
         Args:
             releases: list of sha1s
 
         Returns:
             Generates the list of releases dict with the following keys:
             - id: origin's id
             - revision: origin's type
             - url: origin's url
             - lister: lister's uuid
             - project: project's uuid (FIXME, retrieve this information)
 
         Raises:
             ValueError if the keys does not match (url and type) nor id.
 
         """
         db = self.db
 
         keys = ['id', 'target', 'target_type', 'date', 'date_offset',
                 'date_neg_utc_offset', 'name', 'comment', 'synthetic',
                 'author_id', 'author_name', 'author_email']
 
         # Create temporary table for metadata injection
         db.store_tmp_bytea(releases, cur)
 
         for release in db.release_get_from_temp(cur):
             yield converters.db_to_release(dict(zip(keys, release)))
 
     @db_transaction
     def occurrence_add(self, occurrences, cur=None):
         """Add occurrences to the storage
 
         Args:
             occurrences: iterable of dictionaries representing the individual
                 occurrences to add. Each dict has the following keys:
                 - origin (int): id of the origin corresponding to the
                     occurrence
                 - branch (str): the reference name of the occurrence
                 - target (sha1_git): the id of the object pointed to by
                     the occurrence
                 - target_type (str): the type of object pointed to by the
                     occurrence
                 - date (datetime.DateTime): the validity date for the given
                     occurrence
         """
         db = self.db
 
         processed = []
         for occurrence in occurrences:
             if isinstance(occurrence['date'], str):
                 occurrence['date'] = dateutil.parser.parse(occurrence['date'])
             processed.append(occurrence)
 
         db.mktemp_occurrence_history(cur)
         db.copy_to(processed, 'tmp_occurrence_history',
                    ['origin', 'branch', 'target', 'target_type', 'date'], cur)
 
         db.occurrence_history_add_from_temp(cur)
 
     @db_transaction_generator
     def occurrence_get(self, origin_id, cur=None):
         """Retrieve occurrence information per origin_id.
 
         Args:
             origin_id: The occurrence's origin.
 
         Yields:
             List of occurrences matching criterion.
 
         """
         db = self.db
         for line in db.occurrence_get(origin_id, cur):
             yield {
                 'origin': line[0],
                 'branch': line[1],
                 'target': line[2],
                 'target_type': line[3],
             }
 
     @db_transaction_generator
     def revision_get_by(self,
                         origin_id,
                         branch_name=None,
                         timestamp=None,
                         limit=None,
                         cur=None):
         """Given an origin_id, retrieve occurrences' list per given criterions.
 
         Args:
             origin_id: The origin to filter on.
             branch_name: optional branch name.
             timestamp:
             limit:
 
         Yields:
             List of occurrences matching the criterions or None if nothing is
             found.
 
         """
         keys = ('id', 'date', 'date_offset', 'date_neg_utc_offset',
                 'committer_date', 'committer_date_offset',
                 'committer_date_neg_utc_offset', 'type', 'directory',
                 'message', 'author_id', 'author_name', 'author_email',
                 'committer_id', 'committer_name', 'committer_email',
                 'metadata', 'synthetic', 'parents')
 
         for line in self.db.revision_get_by(origin_id,
                                             branch_name,
                                             timestamp,
                                             limit=limit,
                                             cur=cur):
             data = converters.db_to_revision(dict(zip(keys, line)))
             if not data['type']:
                 yield None
                 continue
             yield data
 
     def release_get_by(self, origin_id, limit=None):
         """Given an origin id, return all the tag objects pointing to heads of
         origin_id.
 
         Args:
             origin_id: the origin to filter on.
             limit: None by default
 
         Yields:
             List of releases matching the criterions or None if nothing is
             found.
 
         """
         keys = ('id', 'target', 'target_type', 'date', 'date_offset',
                 'date_neg_utc_offset', 'name', 'comment', 'synthetic',
                 'author_id', 'author_name', 'author_email')
 
         for line in self.db.release_get_by(origin_id, limit=limit):
             data = converters.db_to_release(dict(zip(keys, line)))
             yield data
 
     @db_transaction
     def object_find_by_sha1_git(self, ids, cur=None):
         """Return the objects found with the given ids.
 
         Args:
             ids: a generator of sha1_gits
         Returns:
             a dict mapping the id to the list of objects found. Each object
             found is itself a dict with keys:
                 sha1_git: the input id
                 type: the type of object found
                 id: the id of the object found
                 object_id: the numeric id of the object found.
         """
         db = self.db
 
         ret = {id: [] for id in ids}
 
         for retval in db.object_find_by_sha1_git(ids):
             if retval[1]:
                 ret[retval[0]].append(dict(zip(db.object_find_by_sha1_git_cols,
                                                retval)))
 
         return ret
 
     @db_transaction
     def origin_get(self, origin, cur=None):
         """Return the origin either identified by its id or its tuple
         (type, url).
 
         Args:
             origin: dictionary representing the individual
                 origin to find.
                 This dict has either the keys type and url:
                 - type (FIXME: enum TBD): the origin type ('git', 'wget', ...)
                 - url (bytes): the url the origin points to
                 either the id:
                 - id: the origin id
 
         Returns:
             the origin dict with the keys:
             - id: origin's id
             - type: origin's type
             - url: origin's url
             - lister: lister's uuid
             - project: project's uuid (FIXME, retrieve this information)
 
         Raises:
             ValueError if the keys does not match (url and type) nor id.
 
         """
         db = self.db
 
         keys = ['id', 'type', 'url', 'lister', 'project']
 
         origin_id = origin.get('id')
         if origin_id:  # check lookup per id first
             ori = db.origin_get(origin_id, cur)
         elif 'type' in origin and 'url' in origin:  # or lookup per type, url
             ori = db.origin_get_with(origin['type'], origin['url'], cur)
         else:  # unsupported lookup
             raise ValueError('Origin must have either id or (type and url).')
 
         if ori:
             return dict(zip(keys, ori))
         return None
 
     @db_transaction
     def _person_add(self, person, cur=None):
         """Add a person in storage.
 
         BEWARE: Internal function for now.
         Do not do anything fancy in case a person already exists.
         Please adapt code if more checks are needed.
 
         Args:
             person dictionary with keys name and email.
 
         Returns:
             Id of the new person.
 
         """
         db = self.db
 
         return db.person_add(person['name'], person['email'])
 
     @db_transaction_generator
     def person_get(self, person, cur=None):
         """Return the persons identified by their ids.
 
         Args:
             person: array of ids.
 
         Returns:
             The array of persons corresponding of the ids.
 
         """
         db = self.db
 
         keys = ['id', 'name', 'email']
 
         for person in db.person_get(person):
             yield dict(zip(keys, person))
 
     @db_transaction
     def origin_add_one(self, origin, cur=None):
         """Add origin to the storage
 
         Args:
             origin: dictionary representing the individual
                 origin to add. This dict has the following keys:
                 - type (FIXME: enum TBD): the origin type ('git', 'wget', ...)
                 - url (bytes): the url the origin points to
 
         Returns:
             the id of the added origin, or of the identical one that already
             exists.
 
         """
         db = self.db
 
         data = db.origin_get_with(origin['type'], origin['url'], cur)
         if data:
             return data[0]
 
         return db.origin_add(origin['type'], origin['url'], cur)
 
     @db_transaction
     def fetch_history_start(self, origin_id, cur=None):
         """Add an entry for origin origin_id in fetch_history. Returns the id
         of the added fetch_history entry
         """
         fetch_history = {
             'origin': origin_id,
             'date': datetime.datetime.now(tz=datetime.timezone.utc),
         }
 
         return self.db.create_fetch_history(fetch_history, cur)
 
     @db_transaction
     def fetch_history_end(self, fetch_history_id, data, cur=None):
         """Close the fetch_history entry with id `fetch_history_id`, replacing
            its data with `data`.
         """
         now = datetime.datetime.now(tz=datetime.timezone.utc)
         fetch_history = self.db.get_fetch_history(fetch_history_id, cur)
 
         if not fetch_history:
             raise ValueError('No fetch_history with id %d' % fetch_history_id)
 
         fetch_history['duration'] = now - fetch_history['date']
 
         fetch_history.update(data)
 
         self.db.update_fetch_history(fetch_history, cur)
 
     @db_transaction
     def fetch_history_get(self, fetch_history_id, cur=None):
         """Get the fetch_history entry with id `fetch_history_id`.
         """
         return self.db.get_fetch_history(fetch_history_id, cur)
 
     @db_transaction
     def entity_add(self, entities, cur=None):
         """Add the given entitites to the database (in entity_history).
 
         Args:
             - entities: iterable of dictionaries containing the following keys:
                 - uuid (uuid): id of the entity
                 - parent (uuid): id of the parent entity
                 - name (str): name of the entity
                 - type (str): type of entity (one of 'organization',
                     'group_of_entities', 'hosting', 'group_of_persons',
                     'person', 'project')
                 - description (str, optional): description of the entity
                 - homepage (str): url of the entity's homepage
                 - active (bool): whether the entity is active
                 - generated (bool): whether the entity was generated
                 - lister_metadata (dict): lister-specific entity metadata
                 - metadata (dict): other metadata for the entity
                 - validity (datetime.DateTime array): timestamps at which we
                     listed the entity.
         """
         db = self.db
 
         cols = list(db.entity_history_cols)
         cols.remove('id')
 
         db.mktemp_entity_history()
         db.copy_to(entities, 'tmp_entity_history', cols, cur)
         db.entity_history_add_from_temp()
 
     @db_transaction_generator
     def entity_get_from_lister_metadata(self, entities, cur=None):
         """Fetch entities from the database, matching with the lister and
            associated metadata.
 
         Args:
             entities: iterable of dictionaries containing the lister metadata
                to look for. Useful keys are 'lister', 'type', 'id', ...
         Returns:
             A generator of fetched entities with all their attributes. If no
             match was found, the returned entity is None.
         """
 
         db = self.db
 
         db.mktemp_entity_lister(cur)
 
         mapped_entities = []
         for i, entity in enumerate(entities):
             mapped_entity = {
                 'id': i,
                 'lister_metadata': entity,
             }
             mapped_entities.append(mapped_entity)
 
         db.copy_to(mapped_entities, 'tmp_entity_lister',
                    ['id', 'lister_metadata'], cur)
 
         cur.execute('''select id, %s
                        from swh_entity_from_tmp_entity_lister()
                        order by id''' %
                     ','.join(db.entity_cols))
 
         for id, *entity_vals in cur:
             fetched_entity = dict(zip(db.entity_cols, entity_vals))
             if fetched_entity['uuid']:
                 yield fetched_entity
             else:
                 yield {
                     'uuid': None,
                     'lister_metadata': entities[i],
                 }
 
     @db_transaction_generator
     def entity_get(self, uuid, cur=None):
         """Returns the list of entity per its uuid identifier and also its
         parent hierarchy.
 
         Args:
             uuid: entity's identifier
 
         Returns:
             List of entities starting with entity with uuid and the parent
             hierarchy from such entity.
 
         """
         db = self.db
         for entity in db.entity_get(uuid, cur):
             yield dict(zip(db.entity_cols, entity))
 
     @db_transaction
     def entity_get_one(self, uuid, cur=None):
         """Returns one entity using its uuid identifier.
 
         Args:
             uuid: entity's identifier
 
         Returns:
             the object corresponding to the given entity
 
         """
         db = self.db
         entity = db.entity_get_one(uuid, cur)
         if entity:
             return dict(zip(db.entity_cols, entity))
         else:
             return None
 
     @db_transaction
     def stat_counters(self, cur=None):
         """compute statistics about the number of tuples in various tables
 
         Returns:
             a dictionary mapping textual labels (e.g., content) to integer
             values (e.g., the number of tuples in table content)
 
         """
         return {k: v for (k, v) in self.db.stat_counters()}