diff --git a/sql/swh-func.sql b/sql/swh-func.sql
index 015b3d1e..9ae558e6 100644
--- a/sql/swh-func.sql
+++ b/sql/swh-func.sql
@@ -1,168 +1,211 @@
 
 -- 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 $$
 begin
     execute format('
 	create temporary table tmp_%I
 	    (like %I including defaults)
 	    on commit drop
 	', tblname, tblname);
     return;
 end
 $$;
 
--- create a temporary table for directory entries called tmp_directory_entry_TBLNAME, mimicking existing table
--- directory_entry_TBLNAME with an extra dir_id (sha1_git) column
+-- 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 $$
 begin
     execute format('
 	create temporary table tmp_%I
 	    (like %I including defaults, dir_id sha1_git)
-	    on commit drop; alter table tmp_%I alter id set default nextval(''%I_id_seq'');
+	    on commit drop;
+        alter table tmp_%I drop column id;
 	', tblname, tblname, tblname, tblname);
     return;
 end
 $$;
 
 
 -- 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 $$
 begin
     return query
 	select sha1, sha1_git, sha256 from tmp_content
 	except
 	select sha1, sha1_git, sha256 from content;
     return;
 end
 $$;
 
 
 -- 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 $$
 declare
     rows bigint;
 begin
     insert into content (sha1, sha1_git, sha256, length, status)
 	select distinct sha1, sha1_git, sha256, length, status
 	from tmp_content
 	where (sha1, sha1_git, sha256) in
 	    (select * from swh_content_missing());
 	    -- TODO XXX use postgres 9.5 "UPSERT" support here, when available.
 	    -- Specifically, using "INSERT .. ON CONFLICT IGNORE" we can avoid
 	    -- the extra swh_content_missing() query here.
     return;
 end
 $$;
 
 
 -- 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 directory
     language plpgsql
 as $$
 begin
     return query
 	select id from tmp_directory
 	except
 	select id from directory;
     return;
 end
 $$;
 
--- Add directory_entry_dir entries
+-- Add tmp_directory_entry_dir entries to directory_entry_dir and
+-- directory_list_dir, skipping duplicates in directory_entry_dir.
+--
+-- operates in bulk: 0. swh_mktemp_dir_entry('directory_entry_dir'), 1 COPY to
+-- tmp_directory_entry_dir, 2. call this function
 create or replace function swh_directory_entry_dir_add()
     returns void
     language plpgsql
 as $$
 begin
-    with inserted_entries as (
-        insert into directory_entry_dir (
-            target, perms, atime, mtime, ctime, name
-        )
-        select t.target, t.perms, t.atime, t.mtime, t.ctime, t.name
-        from tmp_directory_entry_dir t
-        returning id, target, perms, atime, mtime, ctime, name
-    ) insert into directory_list_dir (entry_id, dir_id)
-      select i.id, t.dir_id from tmp_directory_entry_dir t left join inserted_entries i on
-      t.target = i.target and t.perms = i.perms and coalesce(t.atime, '-infinity') = coalesce(i.atime, '-infinity') and coalesce(t.ctime, '-infinity') = coalesce(i.ctime, '-infinity') and coalesce(t.mtime, '-infinity') = coalesce(i.mtime, '-infinity') and t.name = i.name;
+    insert into directory_entry_dir (target, name, perms, atime, mtime, ctime)
+    select t.target, t.name, t.perms, t.atime, t.mtime, t.ctime
+    from tmp_directory_entry_dir t
+    where not exists (
+    select 1
+    from directory_entry_dir i
+    where t.target = i.target and t.name = i.name and t.perms = i.perms and
+       t.atime is not distinct from i.atime and
+       t.mtime is not distinct from i.mtime and
+       t.ctime is not distinct from i.ctime);
+
+    insert into directory_list_dir (entry_id, dir_id)
+    select i.id, t.dir_id
+    from tmp_directory_entry_dir t
+    inner join directory_entry_dir i
+    on t.target = i.target and t.name = i.name and t.perms = i.perms and
+       t.atime is not distinct from i.atime and
+       t.mtime is not distinct from i.mtime and
+       t.ctime is not distinct from i.ctime;
     return;
 end
 $$;
 
--- Add directory_entry_file entries
+-- Add tmp_directory_entry_file entries to directory_entry_file and
+-- directory_list_file, skipping duplicates in directory_entry_file.
+--
+-- operates in bulk: 0. swh_mktemp_dir_entry('directory_entry_file'), 1 COPY to
+-- tmp_directory_entry_file, 2. call this function
 create or replace function swh_directory_entry_file_add()
     returns void
     language plpgsql
 as $$
 begin
-    with inserted_entries as (
-        insert into directory_entry_file (
-            target, perms, atime, mtime, ctime, name
-        )
-        select t.target, t.perms, t.atime, t.mtime, t.ctime, t.name
-        from tmp_directory_entry_file t
-        returning id, target, perms, atime, mtime, ctime, name
-    ) insert into directory_list_file (entry_id, dir_id)
-      select i.id, t.dir_id from tmp_directory_entry_file t left join inserted_entries i on
-      t.target = i.target and t.perms = i.perms and coalesce(t.atime, '-infinity') = coalesce(i.atime, '-infinity') and coalesce(t.ctime, '-infinity') = coalesce(i.ctime, '-infinity') and coalesce(t.mtime, '-infinity') = coalesce(i.mtime, '-infinity') and t.name = i.name;
+    insert into directory_entry_file (target, name, perms, atime, mtime, ctime)
+    select t.target, t.name, t.perms, t.atime, t.mtime, t.ctime
+    from tmp_directory_entry_file t
+    where not exists (
+    select 1
+    from directory_entry_file i
+    where t.target = i.target and t.name = i.name and t.perms = i.perms and
+       t.atime is not distinct from i.atime and
+       t.mtime is not distinct from i.mtime and
+       t.ctime is not distinct from i.ctime);
+
+    insert into directory_list_file (entry_id, dir_id)
+    select i.id, t.dir_id
+    from tmp_directory_entry_file t
+    inner join directory_entry_file i
+    on t.target = i.target and t.name = i.name and t.perms = i.perms and
+       t.atime is not distinct from i.atime and
+       t.mtime is not distinct from i.mtime and
+       t.ctime is not distinct from i.ctime;
     return;
 end
 $$;
 
--- Add directory_entry_rev entries
+-- Add tmp_directory_entry_rev entries to directory_entry_rev and
+-- directory_list_rev, skipping duplicates in directory_entry_rev.
+--
+-- operates in bulk: 0. swh_mktemp_dir_entry('directory_entry_rev'), 1 COPY to
+-- tmp_directory_entry_rev, 2. call this function
 create or replace function swh_directory_entry_rev_add()
     returns void
     language plpgsql
 as $$
 begin
-    with inserted_entries as (
-        insert into directory_entry_rev (
-            target, perms, atime, mtime, ctime, name
-        )
-        select t.target, t.perms, t.atime, t.mtime, t.ctime, t.name
-        from tmp_directory_entry_rev t
-        returning id, target, perms, atime, mtime, ctime, name
-    ) insert into directory_list_rev (entry_id, dir_id)
-      select i.id, t.dir_id from tmp_directory_entry_rev t left join inserted_entries i on
-      t.target = i.target and t.perms = i.perms and coalesce(t.atime, '-infinity') = coalesce(i.atime, '-infinity') and coalesce(t.ctime, '-infinity') = coalesce(i.ctime, '-infinity') and coalesce(t.mtime, '-infinity') = coalesce(i.mtime, '-infinity') and t.name = i.name;
+    insert into directory_entry_rev (target, name, perms, atime, mtime, ctime)
+    select t.target, t.name, t.perms, t.atime, t.mtime, t.ctime
+    from tmp_directory_entry_rev t
+    where not exists (
+    select 1
+    from directory_entry_rev i
+    where t.target = i.target and t.name = i.name and t.perms = i.perms and
+       t.atime is not distinct from i.atime and
+       t.mtime is not distinct from i.mtime and
+       t.ctime is not distinct from i.ctime);
+
+    insert into directory_list_rev (entry_id, dir_id)
+    select i.id, t.dir_id
+    from tmp_directory_entry_rev t
+    inner join directory_entry_rev i
+    on t.target = i.target and t.name = i.name and t.perms = i.perms and
+       t.atime is not distinct from i.atime and
+       t.mtime is not distinct from i.mtime and
+       t.ctime is not distinct from i.ctime;
     return;
 end
 $$;