diff --git a/sql/Makefile b/sql/Makefile
index 20a10b1ba..825616686 100644
--- a/sql/Makefile
+++ b/sql/Makefile
@@ -1,54 +1,55 @@
 # Depends: postgresql-client, postgresql-autodoc
 
 DBNAME = softwareheritage-dev
 DOCDIR = autodoc
 
-SQL_INIT   = swh-init.sql
-SQL_ENUMS = swh-enums.sql
-SQL_SCHEMA = swh-schema.sql
-SQL_FUNC   = swh-func.sql
-SQL_DATA   = swh-data.sql
-SQLS = $(SQL_INIT) $(SQL_ENUMS) $(SQL_SCHEMA) $(SQL_FUNC) $(SQL_DATA)
+SQL_INIT    = swh-init.sql
+SQL_ENUMS   = swh-enums.sql
+SQL_SCHEMA  = swh-schema.sql
+SQL_FUNC    = swh-func.sql
+SQL_DATA    = swh-data.sql
+SQL_INDEX   = swh-indexes.sql
+SQL_TRIGGER = swh-triggers.sql
+SQLS = $(SQL_INIT) $(SQL_ENUMS) $(SQL_SCHEMA) $(SQL_FUNC) $(SQL_INDEX) $(SQL_TRIGGER) $(SQL_DATA)
 
 PSQL_BIN = psql
-PSQL_FLAGS = --single-transaction --echo-all -X
+PSQL_FLAGS = --echo-all -X -v ON_ERROR_STOP=1
 PSQL = $(PSQL_BIN) $(PSQL_FLAGS)
 
-
 all:
 
 createdb: createdb-stamp
 createdb-stamp: $(SQL_INIT)
 	createdb $(DBNAME)
 	touch $@
 
 filldb: filldb-stamp
 filldb-stamp: createdb-stamp
 	cat $(SQLS) | $(PSQL) $(DBNAME)
 	touch $@
 
 dropdb:
 	-dropdb $(DBNAME)
 
 dumpdb: swh.dump
 swh.dump: filldb-stamp
 	pg_dump -Fc $(DBNAME) > $@
 
 doc: autodoc-stamp $(DOCDIR)/swh.pdf
 autodoc-stamp: filldb-stamp
 	test -d $(DOCDIR)/ || mkdir $(DOCDIR)
 	postgresql_autodoc -d $(DBNAME) -f $(DOCDIR)/swh
 	cp -a $(DOCDIR)/swh.dot $(DOCDIR)/swh.dot.orig
 	touch $@
 
 $(DOCDIR)/swh.pdf: clusters.dot autodoc-stamp
 	bin/dot_add_content $(DOCDIR)/swh.dot.orig clusters.dot > $(DOCDIR)/swh.dot
 	dot -T pdf $(DOCDIR)/swh.dot > $(DOCDIR)/swh.pdf
 
 clean:
 	rm -rf *-stamp $(DOCDIR)/
 
 distclean: clean dropdb
 	rm -f swh.dump
 
 .PHONY: all initdb createdb dropdb doc clean
diff --git a/sql/swh-indexes.sql b/sql/swh-indexes.sql
new file mode 100644
index 000000000..e2fd58dc4
--- /dev/null
+++ b/sql/swh-indexes.sql
@@ -0,0 +1,272 @@
+-- content
+
+create unique index concurrently content_pkey on content(sha1);
+create unique index concurrently on content(sha1_git);
+create unique index concurrently on content(sha256);
+create index concurrently on content(ctime);  -- TODO use a BRIN index here (postgres >= 9.5)
+create index concurrently on content(object_id);
+
+alter table content add primary key using index content_pkey;
+
+
+-- entity_history
+
+create unique index concurrently entity_history_pkey on entity_history(id);
+create index concurrently on entity_history(uuid);
+create index concurrently on entity_history(name);
+
+alter table entity_history add primary key using index entity_history_pkey;
+
+-- entity
+
+create unique index concurrently entity_pkey on entity(uuid);
+
+create index concurrently on entity(name);
+create index concurrently on entity using gin(lister_metadata jsonb_path_ops);
+
+alter table entity add primary key using index entity_pkey;
+alter table entity add constraint entity_parent_fkey foreign key (parent) references entity(uuid) deferrable initially deferred not valid;
+alter table entity validate constraint entity_parent_fkey;
+alter table entity add constraint entity_last_id_fkey foreign key (last_id) references entity_history(id) not valid;
+alter table entity validate constraint entity_last_id_fkey;
+
+-- entity_equivalence
+
+create unique index concurrently entity_equivalence_pkey on entity_equivalence(entity1, entity2);
+alter table entity_equivalence add primary key using index entity_equivalence_pkey;
+
+
+alter table entity_equivalence add constraint "entity_equivalence_entity1_fkey" foreign key (entity1) references entity(uuid) not valid;
+alter table entity_equivalence validate constraint entity_equivalence_entity1_fkey;
+alter table entity_equivalence add constraint "entity_equivalence_entity2_fkey" foreign key (entity2) references entity(uuid) not valid;
+alter table entity_equivalence validate constraint entity_equivalence_entity2_fkey;
+alter table entity_equivalence add constraint "order_entities" check (entity1 < entity2) not valid;
+alter table entity_equivalence validate constraint order_entities;
+
+-- listable_entity
+
+create unique index concurrently listable_entity_pkey on listable_entity(uuid);
+alter table listable_entity add primary key using index listable_entity_pkey;
+
+alter table listable_entity add constraint listable_entity_uuid_fkey foreign key (uuid) references entity(uuid) not valid;
+alter table listable_entity validate constraint listable_entity_uuid_fkey;
+
+-- list_history
+
+create unique index concurrently list_history_pkey on list_history(id);
+alter table list_history add primary key using index list_history_pkey;
+
+alter table list_history add constraint list_history_entity_fkey foreign key (entity) references listable_entity(uuid) not valid;
+alter table list_history validate constraint list_history_entity_fkey;
+
+-- origin
+create unique index concurrently origin_pkey on origin(id);
+alter table origin add primary key using index origin_pkey;
+
+create index concurrently on origin(type, url);
+
+alter table origin add constraint origin_lister_fkey foreign key (lister) references listable_entity(uuid) not valid;
+alter table origin validate constraint origin_lister_fkey;
+
+alter table origin add constraint origin_project_fkey foreign key (project) references entity(uuid) not valid;
+alter table origin validate constraint origin_project_fkey;
+
+-- skipped_content
+
+alter table skipped_content add constraint skipped_content_sha1_sha1_git_sha256_key unique (sha1, sha1_git, sha256);
+
+create unique index concurrently on skipped_content(sha1);
+create unique index concurrently on skipped_content(sha1_git);
+create unique index concurrently on skipped_content(sha256);
+create index concurrently on skipped_content(object_id);
+
+alter table skipped_content add constraint skipped_content_origin_fkey foreign key (origin) references origin(id) not valid;
+alter table skipped_content validate constraint skipped_content_origin_fkey;
+
+-- fetch_history
+
+create unique index concurrently fetch_history_pkey on fetch_history(id);
+alter table fetch_history add primary key using index fetch_history_pkey;
+
+alter table fetch_history add constraint fetch_history_origin_fkey foreign key (origin) references origin(id) not valid;
+alter table fetch_history validate constraint fetch_history_origin_fkey;
+
+-- directory
+
+create unique index concurrently directory_pkey on directory(id);
+alter table directory add primary key using index directory_pkey;
+
+create index concurrently on directory using gin (dir_entries);
+create index concurrently on directory using gin (file_entries);
+create index concurrently on directory using gin (rev_entries);
+create index concurrently on directory(object_id);
+
+-- directory_entry_dir
+
+create unique index concurrently directory_entry_dir_pkey on directory_entry_dir(id);
+alter table directory_entry_dir add primary key using index directory_entry_dir_pkey;
+
+create unique index concurrently on directory_entry_dir(target, name, perms);
+
+-- directory_entry_file
+
+create unique index concurrently directory_entry_file_pkey on directory_entry_file(id);
+alter table directory_entry_file add primary key using index directory_entry_file_pkey;
+
+create unique index concurrently on directory_entry_file(target, name, perms);
+
+-- directory_entry_rev
+
+create unique index concurrently directory_entry_rev_pkey on directory_entry_rev(id);
+alter table directory_entry_rev add primary key using index directory_entry_rev_pkey;
+
+create unique index concurrently on directory_entry_rev(target, name, perms);
+
+-- person
+create unique index concurrently person_pkey on person(id);
+alter table person add primary key using index person_pkey;
+
+create unique index concurrently on person(fullname);
+create index concurrently on person(name);
+create index concurrently on person(email);
+
+-- revision
+create unique index concurrently revision_pkey on revision(id);
+alter table revision add primary key using index revision_pkey;
+
+alter table revision add constraint revision_author_fkey foreign key (author) references person(id) not valid;
+alter table revision validate constraint revision_author_fkey;
+alter table revision add constraint revision_committer_fkey foreign key (committer) references person(id) not valid;
+alter table revision validate constraint revision_committer_fkey;
+
+create index concurrently on revision(directory);
+create index concurrently on revision(object_id);
+
+-- revision_history
+create unique index concurrently revision_history_pkey on revision_history(id, parent_rank);
+alter table revision_history add primary key using index revision_history_pkey;
+
+create index concurrently on revision_history(parent_id);
+
+alter table revision_history add constraint revision_history_id_fkey foreign key (id) references revision(id) not valid;
+alter table revision_history validate constraint revision_history_id_fkey;
+
+-- origin_visit
+create unique index concurrently origin_visit_pkey on origin_visit(origin, visit);
+alter table origin_visit add primary key using index origin_visit_pkey;
+
+create index concurrently on origin_visit(date);
+
+alter table origin_visit add constraint origin_visit_origin_fkey foreign key (origin) references origin(id) not valid;
+alter table origin_visit validate constraint origin_visit_origin_fkey;
+
+-- occurrence_history
+create unique index concurrently occurrence_history_pkey on occurrence_history(object_id);
+alter table occurrence_history add primary key using index occurrence_history_pkey;
+
+create index concurrently on occurrence_history(target, target_type);
+create index concurrently on occurrence_history(origin, branch);
+create unique index concurrently on occurrence_history(origin, branch, target, target_type);
+
+alter table occurrence_history add constraint occurrence_history_origin_fkey foreign key (origin) references origin(id) not valid;
+alter table occurrence_history validate constraint occurrence_history_origin_fkey;
+
+-- occurrence
+create unique index concurrently occurrence_pkey on occurrence(origin, branch);
+alter table occurrence add primary key using index occurrence_pkey;
+
+alter table occurrence add constraint occurrence_origin_fkey foreign key (origin) references origin(id) not valid;
+alter table occurrence validate constraint occurrence_origin_fkey;
+
+
+-- release
+create unique index concurrently release_pkey on release(id);
+alter table release add primary key using index release_pkey;
+
+create index concurrently on release(target, target_type);
+create index concurrently on release(object_id);
+
+alter table release add constraint release_author_fkey foreign key (author) references person(id) not valid;
+alter table release validate constraint release_author_fkey;
+
+-- cache_content_revision
+create unique index concurrently cache_content_revision_pkey on cache_content_revision(content);
+alter table cache_content_revision add primary key using index cache_content_revision_pkey;
+
+alter table cache_content_revision add constraint cache_content_revision_content_fkey foreign key (content) references content(sha1_git) not valid;
+alter table cache_content_revision validate constraint cache_content_revision_content_fkey;
+
+-- cache_content_revision_processed
+create unique index concurrently cache_content_revision_processed_pkey on cache_content_revision_processed(revision);
+alter table cache_content_revision_processed add primary key using index cache_content_revision_processed_pkey;
+
+alter table cache_content_revision_processed add constraint cache_content_revision_processed_revision_fkey foreign key (revision) references revision(id) not valid;
+alter table cache_content_revision_processed validate constraint cache_content_revision_processed_revision_fkey;
+
+-- cache_revision_origin
+create unique index concurrently cache_revision_origin_pkey on cache_revision_origin(revision, origin, visit);
+alter table cache_revision_origin add primary key using index cache_revision_origin_pkey;
+
+alter table cache_revision_origin add constraint cache_revision_origin_revision_fkey foreign key (revision) references revision(id) not valid;
+alter table cache_revision_origin validate constraint cache_revision_origin_revision_fkey;
+
+alter table cache_revision_origin add constraint cache_revision_origin_origin_fkey foreign key (origin, visit) references origin_visit(origin, visit) not valid;
+alter table cache_revision_origin validate constraint cache_revision_origin_origin_fkey;
+
+create index concurrently on cache_revision_origin(revision);
+
+-- indexer_configuration
+create unique index concurrently indexer_configuration_pkey on indexer_configuration(id);
+alter table indexer_configuration add primary key using index indexer_configuration_pkey;
+
+create unique index on indexer_configuration(tool_name, tool_version);
+
+-- content_mimetype
+create unique index concurrently content_mimetype_pkey on content_mimetype(id, indexer_configuration_id);
+alter table content_mimetype add primary key using index content_mimetype_pkey;
+
+alter table content_mimetype add constraint content_mimetype_id_fkey foreign key (id) references content(sha1) not valid;
+alter table content_mimetype validate constraint content_mimetype_id_fkey;
+
+alter table content_mimetype add constraint content_mimetype_indexer_configuration_id_fkey foreign key (indexer_configuration_id) references indexer_configuration(id) not valid;
+alter table content_mimetype validate constraint content_mimetype_indexer_configuration_id_fkey;
+
+-- content_language
+create unique index concurrently content_language_pkey on content_language(id, indexer_configuration_id);
+alter table content_language add primary key using index content_language_pkey;
+
+alter table content_language add constraint content_language_id_fkey foreign key (id) references content(sha1) not valid;
+alter table content_language validate constraint content_language_id_fkey;
+
+alter table content_language add constraint content_language_indexer_configuration_id_fkey foreign key (indexer_configuration_id) references indexer_configuration(id) not valid;
+alter table content_language validate constraint content_language_indexer_configuration_id_fkey;
+
+-- content_ctags
+create index concurrently on content_ctags(id);
+create index concurrently on content_ctags(hash_sha1(name));
+create unique index concurrently on content_ctags(id, hash_sha1(name), kind, line, lang, indexer_configuration_id);
+
+alter table content_ctags add constraint content_ctags_id_fkey foreign key (id) references content(sha1) not valid;
+alter table content_ctags validate constraint content_ctags_id_fkey;
+
+alter table content_ctags add constraint content_ctags_indexer_configuration_id_fkey foreign key (indexer_configuration_id) references indexer_configuration(id) not valid;
+alter table content_ctags validate constraint content_ctags_indexer_configuration_id_fkey;
+
+-- fossology_license
+create unique index concurrently fossology_license_pkey on fossology_license(id);
+alter table fossology_license add primary key using index fossology_license_pkey;
+
+create unique index on fossology_license(name);
+
+-- content_fossology_license
+create unique index concurrently content_fossology_license_pkey on content_fossology_license(id, license_id, indexer_configuration_id);
+alter table content_fossology_license add primary key using index content_fossology_license_pkey;
+
+alter table content_fossology_license add constraint content_fossology_license_id_fkey foreign key (id) references content(sha1) not valid;
+alter table content_fossology_license validate constraint content_fossology_license_id_fkey;
+
+alter table content_fossology_license add constraint content_fossology_license_license_id_fkey foreign key (license_id) references fossology_license(id) not valid;
+alter table content_fossology_license validate constraint content_fossology_license_license_id_fkey;
+
+alter table content_fossology_license add constraint content_fossology_license_indexer_configuration_id_fkey foreign key (indexer_configuration_id) references indexer_configuration(id) not valid;
+alter table content_fossology_license validate constraint content_fossology_license_indexer_configuration_id_fkey;
diff --git a/sql/swh-schema.sql b/sql/swh-schema.sql
index f05c73a85..d800862c1 100644
--- a/sql/swh-schema.sql
+++ b/sql/swh-schema.sql
@@ -1,652 +1,460 @@
 ---
 --- 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(97, now(), 'Work In Progress');
+      values(98, 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;
 
 -- 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      sha1 not null,
   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)
-create index on content(object_id);
-
--- Asynchronous notification of new content insertions
-create function notify_new_content()
-  returns trigger
-  language plpgsql
-as $$
-  begin
-    perform pg_notify('new_content', encode(new.sha1, 'hex'));
-    return null;
-  end;
-$$;
-
-create trigger notify_new_content
-  after insert on content
-  for each row
-  execute procedure notify_new_content();
-
 
 -- 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.
 
 -- 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,
+  id               bigserial not null,
   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,
+  uuid             uuid not null,
+  parent           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,
   last_seen        timestamptz,      -- last listing time or disappearance time for active=false
-  last_id          bigint references entity_history(id) -- last listing id
+  last_id          bigint            -- 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)
+  entity1 uuid,
+  entity2 uuid
 );
 
 -- Register a lister for a specific entity.
 create table listable_entity
 (
-  uuid         uuid references entity(uuid) primary key,
+  uuid         uuid,
   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),
+  id        bigserial not null,
+  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,
+  id       bigserial not null,
   type     text, -- TODO use an enum here (?)
   url      text not null,
-  lister   uuid references listable_entity(uuid),
-  project  uuid references entity(uuid)
+  lister   uuid,
+  project  uuid
 );
 
-create index on origin(type, url);
-
--- Asynchronous notification of new origin insertions
-create function notify_new_origin()
-  returns trigger
-  language plpgsql
-as $$
-  begin
-    perform pg_notify('new_origin', new.id::text);
-    return null;
-  end;
-$$;
-
-create trigger notify_new_origin
-  after insert on origin
-  for each row
-  execute procedure notify_new_origin();
-
 -- 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)
+  origin    bigint,
+  object_id bigserial
 );
 
--- 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);
-create index on skipped_content(object_id);
-
--- Asynchronous notification of new skipped content insertions
-create function notify_new_skipped_content()
-  returns trigger
-  language plpgsql
-as $$
-  begin
-  perform pg_notify('new_skipped_content', json_build_object(
-      'sha1', encode(new.sha1, 'hex'),
-      'sha1_git', encode(new.sha1_git, 'hex'),
-      'sha256', encode(new.sha256, 'hex')
-    )::text);
-    return null;
-  end;
-$$;
-
-create trigger notify_new_skipped_content
-  after insert on skipped_content
-  for each row
-  execute procedure notify_new_skipped_content();
-
-
 -- 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),
+  id        bigserial,
+  origin    bigint,
   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,
+  id            sha1_git,
   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);
-create index on directory(object_id);
-
--- Asynchronous notification of new directory insertions
-create function notify_new_directory()
-  returns trigger
-  language plpgsql
-as $$
-  begin
-    perform pg_notify('new_directory', encode(new.id, 'hex'));
-    return null;
-  end;
-$$;
-
-create trigger notify_new_directory
-  after insert on directory
-  for each row
-  execute procedure notify_new_directory();
-
-
 -- A directory entry pointing to a sub-directory.
 create table directory_entry_dir
 (
-  id      bigserial primary key,
+  id      bigserial,
   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,
+  id      bigserial,
   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,
+  id      bigserial,
   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,
+  id        bigserial,
   fullname  bytea not null, -- freeform specification; what is actually used in the checksums
                             --     will usually be of the form 'name <email>'
   name      bytea,          -- advisory: not null if we managed to parse a name
   email     bytea           -- advisory: not null if we managed to parse an email
 );
 
-create unique index on person(fullname);
-create index on person(name);
-create index on person(email);
-
 -- 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,
+  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 not null,
   directory             sha1_git,  -- file-system tree
   message               bytea,
-  author                bigint references person(id),
-  committer             bigint references person(id),
+  author                bigint,
+  committer             bigint,
   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);
-create index on revision(object_id);
-
--- Asynchronous notification of new revision insertions
-create function notify_new_revision()
-  returns trigger
-  language plpgsql
-as $$
-  begin
-    perform pg_notify('new_revision', encode(new.id, 'hex'));
-    return null;
-  end;
-$$;
-
-create trigger notify_new_revision
-  after insert on revision
-  for each row
-  execute procedure notify_new_revision();
-
 
 -- either this table or the sha1_git[] column on the revision table
 create table revision_history
 (
-  id           sha1_git references revision(id),
+  id           sha1_git,
   parent_id    sha1_git,
-  parent_rank  int not null default 0,
+  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),
+  origin    bigint not null,
   visit     bigint not null,
   date      timestamptz not null,
   status    origin_visit_status not null,
-  metadata  jsonb,
-  primary key (origin, visit)
+  metadata  jsonb
 );
 
 comment on column origin_visit.origin is 'Visited origin';
 comment on column origin_visit.visit is 'Visit number the visit occurred for that origin';
 comment on column origin_visit.date is 'Visit date for that origin';
 comment on column origin_visit.status is 'Visit status for that origin';
 comment on column origin_visit.metadata is 'Metadata associated with the visit';
 
-create index on origin_visit(date);
-
--- Asynchronous notification of new origin visits
-create function notify_new_origin_visit()
-  returns trigger
-  language plpgsql
-as $$
-  begin
-    perform pg_notify('new_origin_visit', json_build_object(
-      'origin', new.origin,
-      'visit', new.visit
-    )::text);
-    return null;
-  end;
-$$;
-
-create trigger notify_new_origin_visit
-  after insert on origin_visit
-  for each row
-  execute procedure notify_new_origin_visit();
-
 
 -- 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,
+  origin       bigint 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
+  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);
-create index on occurrence_history(object_id);
-
 -- 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,
+  origin    bigint,
   branch    bytea not null,
   target    sha1_git not null,
-  target_type object_type not null,
-  primary key(origin, branch)
+  target_type object_type not null
 );
 
 -- 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,
+  id          sha1_git,
   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),
+  author      bigint,
   synthetic   boolean not null default false,  -- true if synthetic (cf. swh-loader-tar)
   object_id   bigserial
 );
 
-create index on release(target, target_type);
-create index on release(object_id);
-
--- Asynchronous notification of new release insertions
-create function notify_new_release()
-  returns trigger
-  language plpgsql
-as $$
-  begin
-    perform pg_notify('new_release', encode(new.id, 'hex'));
-    return null;
-  end;
-$$;
-
-create trigger notify_new_release
-  after insert on release
-  for each row
-  execute procedure notify_new_release();
-
 
 -- Content provenance information caches
 -- https://forge.softwareheritage.org/T547
 --
 -- Those tables aren't expected to be exhaustive, and get filled on a case by
 -- case basis: absence of data doesn't mean the data is not there
 
 -- content <-> revision mapping cache
 --
 -- semantics: "we have seen the content with given id in the given path inside
 -- the given revision"
 
 create table cache_content_revision (
-    content         sha1_git not null primary key references content(sha1_git),
+    content         sha1_git not null,
     blacklisted     boolean default false,
     revision_paths  bytea[][]
 );
 
 create table cache_content_revision_processed (
-    revision  sha1_git not null primary key references revision(id)
+    revision  sha1_git not null
 );
 
 -- revision <-> origin_visit mapping cache
 --
 -- semantics: "we have seen the given revision in the given origin during the
 -- given visit"
 
 create table cache_revision_origin (
-   revision  sha1_git not null references revision(id),
+   revision  sha1_git not null,
    origin    bigint not null,
-   visit     bigint not null,
-   primary key (revision, origin, visit),
-   foreign key (origin, visit) references origin_visit (origin, visit)
+   visit     bigint not null
 );
 
-create index on cache_revision_origin(revision);
-
 -- Computing metadata on sha1's contents
 
 create table indexer_configuration (
-  id serial primary key not null,
+  id serial not null,
   tool_name text not null,
   tool_version text not null,
   tool_configuration jsonb
 );
 
 comment on table indexer_configuration is 'Indexer''s configuration version';
 comment on column indexer_configuration.id is 'Tool identifier';
 comment on column indexer_configuration.tool_version is 'Tool name';
 comment on column indexer_configuration.tool_version is 'Tool version';
 comment on column indexer_configuration.tool_configuration is 'Tool configuration: command line, flags, etc...';
 
-create unique index on indexer_configuration(tool_name, tool_version);
-
 -- Properties (mimetype, encoding, etc...)
 create table content_mimetype (
-  id sha1 references content(sha1) not null,
+  id sha1 not null,
   mimetype bytea not null,
   encoding bytea not null,
-  indexer_configuration_id bigserial references indexer_configuration(id) not null,
-  primary key(id, indexer_configuration_id)
+  indexer_configuration_id bigserial
 );
 
 comment on table content_mimetype is 'Metadata associated to a raw content';
 comment on column content_mimetype.mimetype is 'Raw content Mimetype';
 comment on column content_mimetype.encoding is 'Raw content encoding';
 comment on column content_mimetype.indexer_configuration_id is 'Tool used to compute the information';
 
 -- Language metadata
 create table content_language (
-  id sha1 references content(sha1) not null,
+  id sha1 not null,
   lang languages not null,
-  indexer_configuration_id bigserial references indexer_configuration(id) not null,
-  primary key(id, indexer_configuration_id)
+  indexer_configuration_id bigserial
 );
 
 comment on table content_language is 'Language information on a raw content';
 comment on column content_language.lang is 'Language information';
 comment on column content_language.indexer_configuration_id is 'Tool used to compute the information';
 
 -- ctags information per content
 create table content_ctags (
-  id sha1 references content(sha1) not null,
+  id sha1 not null,
   name text not null,
   kind text not null,
   line bigint not null,
   lang ctags_languages not null,
-  indexer_configuration_id bigserial references indexer_configuration(id) not null
+  indexer_configuration_id bigserial
 );
 
 comment on table content_ctags is 'Ctags information on a raw content';
 comment on column content_ctags.id is 'Content identifier';
 comment on column content_ctags.name is 'Symbol name';
 comment on column content_ctags.kind is 'Symbol kind (function, class, variable, const...)';
 comment on column content_ctags.line is 'Symbol line';
 comment on column content_ctags.lang is 'Language information for that content';
 comment on column content_ctags.indexer_configuration_id is 'Tool used to compute the information';
 
-create index on content_ctags(id);
-create index on content_ctags(hash_sha1(name));
-create unique index on content_ctags(id, hash_sha1(name), kind, line, lang, indexer_configuration_id);
-
 create table fossology_license(
-  id smallserial primary key,
+  id smallserial,
   name text not null
 );
 
 comment on table fossology_license is 'Possible license recognized by license indexer';
 comment on column fossology_license.id is 'License identifier';
 comment on column fossology_license.name is 'License name';
 
-create unique index on fossology_license(name);
-
 create table content_fossology_license (
-  id sha1 references content(sha1) not null,
-  license_id smallserial references fossology_license(id) not null,
-  indexer_configuration_id bigserial references indexer_configuration(id) not null,
-  primary key(id, license_id, indexer_configuration_id)
+  id sha1 not null,
+  license_id smallserial not null,
+  indexer_configuration_id bigserial not null
 );
 
 comment on table content_fossology_license is 'license associated to a raw content';
 comment on column content_fossology_license.id is 'Raw content identifier';
 comment on column content_fossology_license.license_id is 'One of the content''s license identifier';
 comment on column content_fossology_license.indexer_configuration_id is 'Tool used to compute the information';
diff --git a/sql/swh-triggers.sql b/sql/swh-triggers.sql
new file mode 100644
index 000000000..c0e7e721d
--- /dev/null
+++ b/sql/swh-triggers.sql
@@ -0,0 +1,124 @@
+-- Asynchronous notification of new content insertions
+create function notify_new_content()
+  returns trigger
+  language plpgsql
+as $$
+  begin
+    perform pg_notify('new_content', encode(new.sha1, 'hex'));
+    return null;
+  end;
+$$;
+
+create trigger notify_new_content
+  after insert on content
+  for each row
+  execute procedure notify_new_content();
+
+
+-- Asynchronous notification of new origin insertions
+create function notify_new_origin()
+  returns trigger
+  language plpgsql
+as $$
+  begin
+    perform pg_notify('new_origin', new.id::text);
+    return null;
+  end;
+$$;
+
+create trigger notify_new_origin
+  after insert on origin
+  for each row
+  execute procedure notify_new_origin();
+
+
+-- Asynchronous notification of new skipped content insertions
+create function notify_new_skipped_content()
+  returns trigger
+  language plpgsql
+as $$
+  begin
+  perform pg_notify('new_skipped_content', json_build_object(
+      'sha1', encode(new.sha1, 'hex'),
+      'sha1_git', encode(new.sha1_git, 'hex'),
+      'sha256', encode(new.sha256, 'hex')
+    )::text);
+    return null;
+  end;
+$$;
+
+create trigger notify_new_skipped_content
+  after insert on skipped_content
+  for each row
+  execute procedure notify_new_skipped_content();
+
+
+-- Asynchronous notification of new directory insertions
+create function notify_new_directory()
+  returns trigger
+  language plpgsql
+as $$
+  begin
+    perform pg_notify('new_directory', encode(new.id, 'hex'));
+    return null;
+  end;
+$$;
+
+create trigger notify_new_directory
+  after insert on directory
+  for each row
+  execute procedure notify_new_directory();
+
+
+-- Asynchronous notification of new revision insertions
+create function notify_new_revision()
+  returns trigger
+  language plpgsql
+as $$
+  begin
+    perform pg_notify('new_revision', encode(new.id, 'hex'));
+    return null;
+  end;
+$$;
+
+create trigger notify_new_revision
+  after insert on revision
+  for each row
+  execute procedure notify_new_revision();
+
+
+-- Asynchronous notification of new origin visits
+create function notify_new_origin_visit()
+  returns trigger
+  language plpgsql
+as $$
+  begin
+    perform pg_notify('new_origin_visit', json_build_object(
+      'origin', new.origin,
+      'visit', new.visit
+    )::text);
+    return null;
+  end;
+$$;
+
+create trigger notify_new_origin_visit
+  after insert on origin_visit
+  for each row
+  execute procedure notify_new_origin_visit();
+
+
+-- Asynchronous notification of new release insertions
+create function notify_new_release()
+  returns trigger
+  language plpgsql
+as $$
+  begin
+    perform pg_notify('new_release', encode(new.id, 'hex'));
+    return null;
+  end;
+$$;
+
+create trigger notify_new_release
+  after insert on release
+  for each row
+  execute procedure notify_new_release();
diff --git a/sql/upgrades/098.sql b/sql/upgrades/098.sql
new file mode 100644
index 000000000..4e5310aaa
--- /dev/null
+++ b/sql/upgrades/098.sql
@@ -0,0 +1,9 @@
+-- SWH DB schema upgrade
+-- from_version: 97
+-- to_version: 98
+-- description: remove duplicate index on occurrence_history(object_id)
+
+insert into dbversion(version, release, description)
+      values(98, now(), 'Work In Progress');
+
+DROP INDEX occurrence_history_object_id_idx;