diff --git a/sql/upgrades/131.sql b/sql/upgrades/131.sql
new file mode 100644
--- /dev/null
+++ b/sql/upgrades/131.sql
@@ -0,0 +1,223 @@
+-- SWH Indexer DB schema upgrade
+-- from_version: 130
+-- to_version: 131
+-- description: _add function returns the inserted rows
+
+insert into dbversion(version, release, description)
+      values(131, now(), 'Work In Progress');
+
+drop function swh_content_mimetype_add(boolean);
+drop function swh_content_language_add(boolean);
+drop function swh_content_ctags_add(boolean);
+drop function swh_content_fossology_license_add(boolean);
+drop function swh_content_metadata_add(boolean);
+drop function swh_revision_intrinsic_metadata_add(boolean);
+drop function swh_origin_intrinsic_metadata_add(boolean);
+
+create or replace function swh_content_mimetype_add(conflict_update boolean)
+    returns bigint
+    language plpgsql
+as $$
+declare
+  res bigint;
+begin
+    if conflict_update then
+        insert into content_mimetype (id, mimetype, encoding, indexer_configuration_id)
+        select id, mimetype, encoding, indexer_configuration_id
+        from tmp_content_mimetype tcm
+        on conflict(id, indexer_configuration_id)
+        do update set mimetype = excluded.mimetype,
+                      encoding = excluded.encoding;
+    else
+        insert into content_mimetype (id, mimetype, encoding, indexer_configuration_id)
+        select id, mimetype, encoding, indexer_configuration_id
+        from tmp_content_mimetype tcm
+        on conflict(id, indexer_configuration_id)
+        do nothing;
+    end if;
+    get diagnostics res = ROW_COUNT;
+    return res;
+end
+$$;
+
+comment on function swh_content_mimetype_add(boolean) IS 'Add new content mimetypes';
+
+create or replace function swh_content_language_add(conflict_update boolean)
+    returns bigint
+    language plpgsql
+as $$
+declare
+  res bigint;
+begin
+    if conflict_update then
+      insert into content_language (id, lang, indexer_configuration_id)
+      select id, lang, indexer_configuration_id
+      from tmp_content_language tcl
+      on conflict(id, indexer_configuration_id)
+      do update set lang = excluded.lang;
+    else
+        insert into content_language (id, lang, indexer_configuration_id)
+        select id, lang, indexer_configuration_id
+    	from tmp_content_language tcl
+        on conflict(id, indexer_configuration_id)
+        do nothing;
+    end if;
+    get diagnostics res = ROW_COUNT;
+    return res;
+end
+$$;
+
+comment on function swh_content_language_add(boolean) IS 'Add new content languages';
+
+
+create or replace function swh_content_ctags_add(conflict_update boolean)
+    returns bigint
+    language plpgsql
+as $$
+declare
+  res bigint;
+begin
+    if conflict_update then
+        delete from content_ctags
+        where id in (select tmp.id
+                     from tmp_content_ctags tmp
+                     inner join indexer_configuration i on i.id=tmp.indexer_configuration_id);
+    end if;
+
+    insert into content_ctags (id, name, kind, line, lang, indexer_configuration_id)
+    select id, name, kind, line, lang, indexer_configuration_id
+    from tmp_content_ctags tct
+    on conflict(id, hash_sha1(name), kind, line, lang, indexer_configuration_id)
+    do nothing;
+    get diagnostics res = ROW_COUNT;
+    return res;
+end
+$$;
+
+comment on function swh_content_ctags_add(boolean) IS 'Add new ctags symbols per content';
+
+create or replace function swh_content_fossology_license_add(conflict_update boolean)
+  returns bigint
+  language plpgsql
+as $$
+declare
+  res bigint;
+begin
+    -- insert unknown licenses first
+    insert into fossology_license (name)
+    select distinct license from tmp_content_fossology_license tmp
+    where not exists (select 1 from fossology_license where name=tmp.license)
+    on conflict(name) do nothing;
+
+    if conflict_update then
+        insert into content_fossology_license (id, license_id, indexer_configuration_id)
+        select tcl.id,
+              (select id from fossology_license where name = tcl.license) as license,
+              indexer_configuration_id
+        from tmp_content_fossology_license tcl
+        on conflict(id, license_id, indexer_configuration_id)
+        do update set license_id = excluded.license_id;
+    end if;
+
+    insert into content_fossology_license (id, license_id, indexer_configuration_id)
+    select tcl.id,
+          (select id from fossology_license where name = tcl.license) as license,
+          indexer_configuration_id
+    from tmp_content_fossology_license tcl
+    on conflict(id, license_id, indexer_configuration_id)
+    do nothing;
+
+    get diagnostics res = ROW_COUNT;
+    return res;
+end
+$$;
+
+create or replace function swh_content_metadata_add(conflict_update boolean)
+    returns bigint
+    language plpgsql
+as $$
+declare
+  res bigint;
+begin
+    if conflict_update then
+      insert into content_metadata (id, metadata, indexer_configuration_id)
+      select id, metadata, indexer_configuration_id
+      from tmp_content_metadata tcm
+      on conflict(id, indexer_configuration_id)
+      do update set metadata = excluded.metadata;
+    else
+        insert into content_metadata (id, metadata, indexer_configuration_id)
+        select id, metadata, indexer_configuration_id
+    	from tmp_content_metadata tcm
+        on conflict(id, indexer_configuration_id)
+        do nothing;
+    end if;
+    get diagnostics res = ROW_COUNT;
+    return res;
+end
+$$;
+
+comment on function swh_content_metadata_add(boolean) IS 'Add new content metadata';
+
+
+create or replace function swh_revision_intrinsic_metadata_add(conflict_update boolean)
+    returns bigint
+    language plpgsql
+as $$
+declare
+  res bigint;
+begin
+    if conflict_update then
+      insert into revision_intrinsic_metadata (id, metadata, mappings, indexer_configuration_id)
+      select id, metadata, mappings, indexer_configuration_id
+      from tmp_revision_intrinsic_metadata tcm
+      on conflict(id, indexer_configuration_id)
+      do update set
+          metadata = excluded.metadata,
+          mappings = excluded.mappings;
+    else
+        insert into revision_intrinsic_metadata (id, metadata, mappings, indexer_configuration_id)
+        select id, metadata, mappings, indexer_configuration_id
+    	from tmp_revision_intrinsic_metadata tcm
+        on conflict(id, indexer_configuration_id)
+        do nothing;
+    end if;
+    get diagnostics res = ROW_COUNT;
+    return res;
+end
+$$;
+
+comment on function swh_revision_intrinsic_metadata_add(boolean) IS 'Add new revision intrinsic metadata';
+
+create or replace function swh_origin_intrinsic_metadata_add(
+        conflict_update boolean)
+    returns bigint
+    language plpgsql
+as $$
+declare
+  res bigint;
+begin
+    perform swh_origin_intrinsic_metadata_compute_tsvector();
+    if conflict_update then
+      insert into origin_intrinsic_metadata (id, metadata, indexer_configuration_id, from_revision, metadata_tsvector, mappings)
+      select id, metadata, indexer_configuration_id, from_revision,
+             metadata_tsvector, mappings
+      from tmp_origin_intrinsic_metadata
+      on conflict(id, indexer_configuration_id)
+      do update set
+          metadata = excluded.metadata,
+          metadata_tsvector = excluded.metadata_tsvector,
+          mappings = excluded.mappings,
+          from_revision = excluded.from_revision;
+    else
+        insert into origin_intrinsic_metadata (id, metadata, indexer_configuration_id, from_revision, metadata_tsvector, mappings)
+        select id, metadata, indexer_configuration_id, from_revision,
+               metadata_tsvector, mappings
+    	from tmp_origin_intrinsic_metadata
+        on conflict(id, indexer_configuration_id)
+        do nothing;
+    end if;
+    get diagnostics res = ROW_COUNT;
+    return res;
+end
+$$;
diff --git a/swh/indexer/ctags.py b/swh/indexer/ctags.py
--- a/swh/indexer/ctags.py
+++ b/swh/indexer/ctags.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2015-2017  The Software Heritage developers
+# Copyright (C) 2015-2020  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
@@ -6,6 +6,8 @@
 import subprocess
 import json
 
+from typing import Dict, List
+
 from swh.model import hashutil
 
 from .indexer import ContentIndexer, write_to_temp
@@ -135,17 +137,18 @@
 
         return ctags
 
-    def persist_index_computations(self, results, policy_update):
+    def persist_index_computations(
+            self, results: List[Dict], policy_update: str) -> Dict:
         """Persist the results in storage.
 
         Args:
-            results ([dict]): list of content_mimetype, dict with the
+            results: list of content_mimetype, dict with the
               following keys:
               - id (bytes): content's identifier (sha1)
               - ctags ([dict]): ctags list of symbols
-            policy_update ([str]): either 'update-dups' or 'ignore-dups' to
+            policy_update: either 'update-dups' or 'ignore-dups' to
               respectively update duplicates or ignore them
 
         """
-        self.idx_storage.content_ctags_add(
+        return self.idx_storage.content_ctags_add(
             results, conflict_update=(policy_update == 'update-dups'))
diff --git a/swh/indexer/fossology_license.py b/swh/indexer/fossology_license.py
--- a/swh/indexer/fossology_license.py
+++ b/swh/indexer/fossology_license.py
@@ -1,17 +1,21 @@
-# Copyright (C) 2016-2018  The Software Heritage developers
+# Copyright (C) 2016-2020  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 logging
 import subprocess
 
-from typing import Optional
+from typing import Any, Dict, List, Optional
 
 from swh.model import hashutil
 from .indexer import ContentIndexer, ContentRangeIndexer, write_to_temp
 
 
-def compute_license(path, log=None):
+logger = logging.getLogger(__name__)
+
+
+def compute_license(path):
     """Determine license from file at path.
 
     Args:
@@ -38,10 +42,9 @@
             'path': path,
         }
     except subprocess.CalledProcessError:
-        if log:
-            from os import path as __path
-            log.exception('Problem during license detection for sha1 %s' %
-                          __path.basename(path))
+        from os import path as __path
+        logger.exception('Problem during license detection for sha1 %s' %
+                         __path.basename(path))
         return {
             'licenses': [],
             'path': path,
@@ -73,7 +76,8 @@
         super().prepare()
         self.working_directory = self.config['workdir']
 
-    def index(self, id, data):
+    def index(self, id: bytes, data: Optional[bytes] = None,
+              **kwargs) -> Dict[str, Any]:
         """Index sha1s' content and store result.
 
         Args:
@@ -90,33 +94,37 @@
 
         """
         assert isinstance(id, bytes)
+        assert data is not None
+        tool = self.tool  # type: ignore
         with write_to_temp(
                 filename=hashutil.hash_to_hex(id),  # use the id as pathname
                 data=data,
                 working_directory=self.working_directory) as content_path:
-            properties = compute_license(path=content_path, log=self.log)
+            properties = compute_license(path=content_path)
             properties.update({
                 'id': id,
-                'indexer_configuration_id': self.tool['id'],
+                'indexer_configuration_id': tool['id'],
             })
         return properties
 
-    def persist_index_computations(self, results, policy_update):
+    def persist_index_computations(
+            self, results: List[Dict], policy_update: str) -> Dict:
         """Persist the results in storage.
 
         Args:
-            results ([dict]): list of content_license, dict with the
+            results: list of content_license dict with the
               following keys:
 
               - id (bytes): content's identifier (sha1)
               - license (bytes): license in bytes
               - path (bytes): path
 
-            policy_update ([str]): either 'update-dups' or 'ignore-dups' to
+            policy_update: either 'update-dups' or 'ignore-dups' to
               respectively update duplicates or ignore them
 
         """
-        self.idx_storage.content_fossology_license_add(
+        idx_storage = self.idx_storage  # type: ignore
+        return idx_storage.content_fossology_license_add(
             results, conflict_update=(policy_update == 'update-dups'))
 
 
diff --git a/swh/indexer/indexer.py b/swh/indexer/indexer.py
--- a/swh/indexer/indexer.py
+++ b/swh/indexer/indexer.py
@@ -10,8 +10,9 @@
 import tempfile
 
 from contextlib import contextmanager
-from typing import Any, Dict, Tuple, Generator, Union, List
-from typing import Set
+from typing import (
+    Any, Dict, Iterator, List, Optional, Set, Tuple, Union
+)
 
 from swh.scheduler import CONFIG as SWH_CONFIG
 
@@ -26,8 +27,7 @@
 
 @contextmanager
 def write_to_temp(
-    filename: str, data: bytes, working_directory: str
-) -> Generator[str, None, None]:
+        filename: str, data: bytes, working_directory: str) -> Iterator[str]:
     """Write the sha1's content in a temporary file.
 
     Args:
@@ -238,9 +238,8 @@
         else:
             return []
 
-    def index(
-        self, id: bytes, data: bytes
-    ) -> Dict[str, Any]:
+    def index(self, id: bytes, data: Optional[bytes] = None,
+              **kwargs) -> Dict[str, Any]:
         """Index computation for the id and associated raw data.
 
         Args:
@@ -255,7 +254,7 @@
         """
         raise NotImplementedError()
 
-    def filter(self, ids: List[bytes]) -> Generator[bytes, None, None]:
+    def filter(self, ids: List[bytes]) -> Iterator[bytes]:
         """Filter missing ids for that particular indexer.
 
         Args:
@@ -268,7 +267,7 @@
         yield from ids
 
     @abc.abstractmethod
-    def persist_index_computations(self, results, policy_update):
+    def persist_index_computations(self, results, policy_update) -> Dict:
         """Persist the computation resulting from the index.
 
         Args:
@@ -279,27 +278,10 @@
               respectively update duplicates or ignore them
 
         Returns:
-            None
+            a summary dict of what has been inserted in the storage
 
         """
-        pass
-
-    @abc.abstractmethod
-    def run(self, ids, policy_update, **kwargs):
-        """Given a list of ids:
-
-        - retrieves the data from the storage
-        - executes the indexing computations
-        - stores the results (according to policy_update)
-
-        Args:
-            ids ([bytes]): id's identifier list
-            policy_update (str): either 'update-dups' or 'ignore-dups' to
-              respectively update duplicates or ignore them
-            **kwargs: passed to the `index` method
-
-        """
-        pass
+        return {}
 
 
 class ContentIndexer(BaseIndexer):
@@ -313,8 +295,8 @@
     methods mentioned in the :class:`BaseIndexer` class.
 
     """
-
-    def run(self, ids, policy_update, **kwargs):
+    def run(self, ids: Union[List[bytes], bytes, str], policy_update: str,
+            **kwargs) -> Dict:
         """Given a list of ids:
 
         - retrieve the content from the storage
@@ -328,12 +310,17 @@
                                  them
             **kwargs: passed to the `index` method
 
+        Returns:
+            A summary Dict of the task's status
+
         """
-        ids = [hashutil.hash_to_bytes(id_) if isinstance(id_, str) else id_
-               for id_ in ids]
+        status = 'uneventful'
+        sha1s = [hashutil.hash_to_bytes(id_) if isinstance(id_, str) else id_
+                 for id_ in ids]
         results = []
+        summary: Dict = {}
         try:
-            for sha1 in ids:
+            for sha1 in sha1s:
                 try:
                     raw_content = self.objstorage.get(sha1)
                 except ObjNotFoundError:
@@ -343,14 +330,18 @@
                 res = self.index(sha1, raw_content, **kwargs)
                 if res:  # If no results, skip it
                     results.append(res)
-
-            self.persist_index_computations(results, policy_update)
+                    status = 'eventful'
+            summary = self.persist_index_computations(results, policy_update)
             self.results = results
         except Exception:
             if not self.catch_exceptions:
                 raise
             self.log.exception(
                 'Problem when reading contents metadata.')
+            status = 'failed'
+        finally:
+            summary['status'] = status
+            return summary
 
 
 class ContentRangeIndexer(BaseIndexer):
@@ -383,7 +374,7 @@
 
     def _list_contents_to_index(
         self, start: bytes, end: bytes, indexed: Set[bytes]
-    ) -> Generator[bytes, None, None]:
+    ) -> Iterator[bytes]:
         """Compute from storage the new contents to index in the range [start,
            end]. The already indexed contents are skipped.
 
@@ -411,7 +402,7 @@
 
     def _index_contents(
         self, start: bytes, end: bytes, indexed: Set[bytes], **kwargs: Any
-    ) -> Generator[Dict, None, None]:
+    ) -> Iterator[Dict]:
         """Index the contents from within range [start, end]
 
         Args:
@@ -430,7 +421,7 @@
                 self.log.warning('Content %s not found in objstorage' %
                                  hashutil.hash_to_hex(sha1))
                 continue
-            res = self.index(sha1, raw_content, **kwargs)  # type: ignore
+            res = self.index(sha1, raw_content, **kwargs)
             if res:
                 if not isinstance(res['id'], bytes):
                     raise TypeError(
@@ -439,8 +430,7 @@
                 yield res
 
     def _index_with_skipping_already_done(
-        self, start: bytes, end: bytes
-    ) -> Generator[Dict, None, None]:
+            self, start: bytes, end: bytes) -> Iterator[Dict]:
         """Index not already indexed contents in range [start, end].
 
         Args:
@@ -460,47 +450,55 @@
                     start, _end, contents)
             start = indexed_page['next']
 
-    def run(self, start, end, skip_existing=True, **kwargs):
+    def run(self, start: Union[bytes, str], end: Union[bytes, str],
+            skip_existing: bool = True, **kwargs) -> Dict:
         """Given a range of content ids, compute the indexing computations on
            the contents within. Either the indexer is incremental
            (filter out existing computed data) or not (compute
            everything from scratch).
 
         Args:
-            start (Union[bytes, str]): Starting range identifier
-            end (Union[bytes, str]): Ending range identifier
-            skip_existing (bool): Skip existing indexed data
+            start: Starting range identifier
+            end: Ending range identifier
+            skip_existing: Skip existing indexed data
               (default) or not
             **kwargs: passed to the `index` method
 
         Returns:
-            bool: True if data was indexed, False otherwise.
+            A dict with the task's status
 
         """
-        with_indexed_data = False
+        status = 'uneventful'
+        summary: Dict = {}
         try:
-            if isinstance(start, str):
-                start = hashutil.hash_to_bytes(start)
-            if isinstance(end, str):
-                end = hashutil.hash_to_bytes(end)
+            range_start = hashutil.hash_to_bytes(start) \
+                if isinstance(start, str) else start
+            range_end = hashutil.hash_to_bytes(end) \
+                if isinstance(end, str) else end
 
             if skip_existing:
-                gen = self._index_with_skipping_already_done(start, end)
+                gen = self._index_with_skipping_already_done(
+                    range_start, range_end)
             else:
-                gen = self._index_contents(start, end, indexed=[])
-
-            for results in utils.grouper(gen,
-                                         n=self.config['write_batch_size']):
-                self.persist_index_computations(
-                    results, policy_update='update-dups')
-                with_indexed_data = True
+                gen = self._index_contents(
+                    range_start, range_end, indexed=set([]))
+
+            for contents in utils.grouper(
+                    gen, n=self.config['write_batch_size']):
+                res = self.persist_index_computations(
+                    contents, policy_update='update-dups')
+                summary['content_mimetype:add'] += res.get(
+                    'content_mimetype:add')
+                status = 'eventful'
         except Exception:
             if not self.catch_exceptions:
                 raise
             self.log.exception(
                 'Problem when computing metadata.')
+            status = 'failed'
         finally:
-            return with_indexed_data
+            summary['status'] = status
+            return summary
 
 
 class OriginIndexer(BaseIndexer):
@@ -513,8 +511,8 @@
     class.
 
     """
-    def run(self, origin_urls, policy_update='update-dups',
-            next_step=None, **kwargs):
+    def run(self, origin_urls: List[str],
+            policy_update: str = 'update-dups', **kwargs) -> Dict:
         """Given a list of origin urls:
 
         - retrieve origins from storage
@@ -522,17 +520,16 @@
         - store the results (according to policy_update)
 
         Args:
-            origin_urls ([str]): list of origin urls.
-            policy_update (str): either 'update-dups' or 'ignore-dups' to
+            origin_urls: list of origin urls.
+            policy_update: either 'update-dups' or 'ignore-dups' to
               respectively update duplicates (default) or ignore them
-            parse_ids (bool): Do we need to parse id or not (default)
             **kwargs: passed to the `index` method
 
         """
         results = self.index_list(origin_urls, **kwargs)
-
-        self.persist_index_computations(results, policy_update)
+        summary = self.persist_index_computations(results, policy_update)
         self.results = results
+        return summary
 
     def index_list(self, origins: List[Any], **kwargs: Any) -> List[Dict]:
         results = []
@@ -560,7 +557,7 @@
     class.
 
     """
-    def run(self, ids, policy_update):
+    def run(self, ids: Union[str, bytes], policy_update: str) -> Dict:
         """Given a list of sha1_gits:
 
         - retrieve revisions from storage
@@ -568,15 +565,15 @@
         - store the results (according to policy_update)
 
         Args:
-            ids ([bytes or str]): sha1_git's identifier list
-            policy_update (str): either 'update-dups' or 'ignore-dups' to
+            ids: sha1_git's identifier list
+            policy_update: either 'update-dups' or 'ignore-dups' to
               respectively update duplicates or ignore them
 
         """
         results = []
-        ids = [hashutil.hash_to_bytes(id_) if isinstance(id_, str) else id_
-               for id_ in ids]
-        revs = self.storage.revision_get(ids)
+        revs = self.storage.revision_get(
+            hashutil.hash_to_bytes(id_) if isinstance(id_, str) else id_
+            for id_ in ids)
 
         for rev in revs:
             if not rev:
@@ -592,5 +589,6 @@
                     raise
                 self.log.exception(
                         'Problem when processing revision')
-        self.persist_index_computations(results, policy_update)
+        summary = self.persist_index_computations(results, policy_update)
         self.results = results
+        return summary
diff --git a/swh/indexer/metadata.py b/swh/indexer/metadata.py
--- a/swh/indexer/metadata.py
+++ b/swh/indexer/metadata.py
@@ -5,7 +5,7 @@
 
 from copy import deepcopy
 
-from typing import Any, List, Dict, Tuple, Callable, Generator
+from typing import Any, Callable, Dict, Iterator, List, Tuple
 
 from swh.core.utils import grouper
 
@@ -26,7 +26,7 @@
 def call_with_batches(
     f: Callable[[List[Dict[str, Any]]], Dict['str', Any]],
     args: List[Dict[str, str]], batch_size: int
-) -> Generator[str, None, None]:
+) -> Iterator[str]:
     """Calls a function with batches of args, and concatenates the results.
     """
     groups = grouper(args, batch_size)
@@ -89,7 +89,7 @@
 
     def persist_index_computations(
         self, results: List[Dict], policy_update: str
-    ) -> None:
+    ) -> Dict:
         """Persist the results in storage.
 
         Args:
@@ -101,7 +101,7 @@
               respectively update duplicates or ignore them
 
         """
-        self.idx_storage.content_metadata_add(
+        return self.idx_storage.content_metadata_add(
             results, conflict_update=(policy_update == 'update-dups'))
 
 
@@ -188,7 +188,7 @@
 
     def persist_index_computations(
         self, results: List[Dict], policy_update: str
-    ) -> None:
+    ) -> Dict:
         """Persist the results in storage.
 
         Args:
@@ -203,7 +203,7 @@
         """
         # TODO: add functions in storage to keep data in
         # revision_intrinsic_metadata
-        self.idx_storage.revision_intrinsic_metadata_add(
+        return self.idx_storage.revision_intrinsic_metadata_add(
             results, conflict_update=(policy_update == 'update-dups'))
 
     def translate_revision_intrinsic_metadata(
@@ -327,7 +327,7 @@
 
     def persist_index_computations(
         self, results: List[Dict], policy_update: str
-    ) -> None:
+    ) -> Dict:
         conflict_update = (policy_update == 'update-dups')
 
         # Deduplicate revisions
@@ -335,6 +335,7 @@
         orig_metadata: List[Any] = []
         revs_to_delete: List[Any] = []
         origs_to_delete: List[Any] = []
+        summary: Dict = {}
         for (orig_item, rev_item) in results:
             assert rev_item['metadata'] == orig_item['metadata']
             if not rev_item['metadata'] or \
@@ -352,17 +353,25 @@
                     orig_metadata.append(orig_item)
 
         if rev_metadata:
-            self.idx_storage.revision_intrinsic_metadata_add(
+            summary_rev = self.idx_storage.revision_intrinsic_metadata_add(
                 rev_metadata, conflict_update=conflict_update)
+            summary.update(summary_rev)
         if orig_metadata:
-            self.idx_storage.origin_intrinsic_metadata_add(
+            summary_ori = self.idx_storage.origin_intrinsic_metadata_add(
                 orig_metadata, conflict_update=conflict_update)
+            summary.update(summary_ori)
 
         # revs_to_delete should always be empty unless we changed a mapping
         # to detect less files or less content.
         # However, origs_to_delete may be empty whenever an upstream deletes
         # a metadata file.
         if origs_to_delete:
-            self.idx_storage.origin_intrinsic_metadata_delete(origs_to_delete)
+            summary_ori = self.idx_storage.origin_intrinsic_metadata_delete(
+                origs_to_delete)
+            summary.update(summary_ori)
         if revs_to_delete:
-            self.idx_storage.revision_intrinsic_metadata_delete(revs_to_delete)
+            summary_rev = self.idx_storage.revision_intrinsic_metadata_delete(
+                revs_to_delete)
+            summary.update(summary_ori)
+
+        return summary
diff --git a/swh/indexer/mimetype.py b/swh/indexer/mimetype.py
--- a/swh/indexer/mimetype.py
+++ b/swh/indexer/mimetype.py
@@ -55,7 +55,8 @@
 
     CONFIG_BASE_FILENAME = 'indexer/mimetype'  # type: Optional[str]
 
-    def index(self, id: bytes, data: bytes) -> Dict[str, Any]:
+    def index(self, id: bytes, data: Optional[bytes] = None,
+              **kwargs) -> Dict[str, Any]:
         """Index sha1s' content and store result.
 
         Args:
@@ -70,6 +71,7 @@
             - encoding: encoding in bytes
 
         """
+        assert data is not None
         properties = compute_mimetype_encoding(data)
         properties.update({
             'id': id,
@@ -78,8 +80,8 @@
         return properties
 
     def persist_index_computations(
-        self, results: List[Dict], policy_update: List[str]
-    ) -> None:
+        self, results: List[Dict], policy_update: str
+    ) -> Dict:
         """Persist the results in storage.
 
         Args:
@@ -90,7 +92,7 @@
                respectively update duplicates or ignore them
 
         """
-        self.idx_storage.content_mimetype_add(
+        return self.idx_storage.content_mimetype_add(
             results, conflict_update=(policy_update == 'update-dups'))
 
 
diff --git a/swh/indexer/origin_head.py b/swh/indexer/origin_head.py
--- a/swh/indexer/origin_head.py
+++ b/swh/indexer/origin_head.py
@@ -24,10 +24,10 @@
 
     def persist_index_computations(
         self, results: Any, policy_update: str
-    ) -> None:
+    ) -> Dict:
         """Do nothing. The indexer's results are not persistent, they
         should only be piped to another indexer."""
-        pass
+        return {}
 
     # Dispatch
 
diff --git a/swh/indexer/rehash.py b/swh/indexer/rehash.py
--- a/swh/indexer/rehash.py
+++ b/swh/indexer/rehash.py
@@ -145,19 +145,25 @@
                 content.update(content_hashes)
                 yield content, checksums_to_compute
 
-    def run(self, contents: List[Dict[str, Any]]) -> None:
+    def run(self, contents: List[Dict[str, Any]]) -> Dict:
         """Given a list of content:
 
           - (re)compute a given set of checksums on contents available in our
             object storage
           - update those contents with the new metadata
 
-          Args:
-              contents: contents as dictionary with necessary keys.
-                  key present in such dictionary should be the ones defined in
-                  the 'primary_key' option.
+        Args:
+            contents: contents as dictionary with necessary keys.
+                key present in such dictionary should be the ones defined in
+                the 'primary_key' option.
+
+        Returns:
+            A summary dict with key 'status', task' status and 'count' the
+            number of updated contents.
 
         """
+        status = 'uneventful'
+        count = 0
         for data in utils.grouper(
                 self.get_new_contents_metadata(contents),
                 self.batch_size_update):
@@ -172,6 +178,13 @@
                 try:
                     self.storage.content_update(contents,
                                                 keys=keys)
+                    count += len(contents)
+                    status = 'eventful'
                 except Exception:
                     self.log.exception('Problem during update.')
                     continue
+
+        return {
+            'status': status,
+            'count': count,
+        }
diff --git a/swh/indexer/sql/30-swh-schema.sql b/swh/indexer/sql/30-swh-schema.sql
--- a/swh/indexer/sql/30-swh-schema.sql
+++ b/swh/indexer/sql/30-swh-schema.sql
@@ -14,7 +14,7 @@
 );
 
 insert into dbversion(version, release, description)
-      values(130, now(), 'Work In Progress');
+      values(131, now(), 'Work In Progress');
 -- Computing metadata on sha1's contents
 
 -- a SHA1 checksum (not necessarily originating from Git)
diff --git a/swh/indexer/sql/40-swh-func.sql b/swh/indexer/sql/40-swh-func.sql
--- a/swh/indexer/sql/40-swh-func.sql
+++ b/swh/indexer/sql/40-swh-func.sql
@@ -47,29 +47,31 @@
 -- swh_content_mimetype_missing must take place before calling this
 -- function.
 --
---
 -- operates in bulk: 0. swh_mktemp(content_mimetype), 1. COPY to tmp_content_mimetype,
 -- 2. call this function
 create or replace function swh_content_mimetype_add(conflict_update boolean)
-    returns void
+    returns bigint
     language plpgsql
 as $$
+declare
+  res bigint;
 begin
     if conflict_update then
         insert into content_mimetype (id, mimetype, encoding, indexer_configuration_id)
         select id, mimetype, encoding, indexer_configuration_id
         from tmp_content_mimetype tcm
-            on conflict(id, indexer_configuration_id)
-                do update set mimetype = excluded.mimetype,
-                              encoding = excluded.encoding;
-
+        on conflict(id, indexer_configuration_id)
+        do update set mimetype = excluded.mimetype,
+                      encoding = excluded.encoding;
     else
         insert into content_mimetype (id, mimetype, encoding, indexer_configuration_id)
         select id, mimetype, encoding, indexer_configuration_id
         from tmp_content_mimetype tcm
-            on conflict(id, indexer_configuration_id) do nothing;
+        on conflict(id, indexer_configuration_id)
+        do nothing;
     end if;
-    return;
+    get diagnostics res = ROW_COUNT;
+    return res;
 end
 $$;
 
@@ -85,25 +87,27 @@
 -- operates in bulk: 0. swh_mktemp(content_language), 1. COPY to
 -- tmp_content_language, 2. call this function
 create or replace function swh_content_language_add(conflict_update boolean)
-    returns void
+    returns bigint
     language plpgsql
 as $$
+declare
+  res bigint;
 begin
     if conflict_update then
       insert into content_language (id, lang, indexer_configuration_id)
       select id, lang, indexer_configuration_id
-    	from tmp_content_language tcl
-            on conflict(id, indexer_configuration_id)
-                do update set lang = excluded.lang;
-
+      from tmp_content_language tcl
+      on conflict(id, indexer_configuration_id)
+      do update set lang = excluded.lang;
     else
         insert into content_language (id, lang, indexer_configuration_id)
         select id, lang, indexer_configuration_id
-    	  from tmp_content_language tcl
-            on conflict(id, indexer_configuration_id)
-            do nothing;
+    	from tmp_content_language tcl
+        on conflict(id, indexer_configuration_id)
+        do nothing;
     end if;
-    return;
+    get diagnostics res = ROW_COUNT;
+    return res;
 end
 $$;
 
@@ -141,9 +145,11 @@
 -- operates in bulk: 0. swh_mktemp(content_ctags), 1. COPY to tmp_content_ctags,
 -- 2. call this function
 create or replace function swh_content_ctags_add(conflict_update boolean)
-    returns void
+    returns bigint
     language plpgsql
 as $$
+declare
+  res bigint;
 begin
     if conflict_update then
         delete from content_ctags
@@ -155,9 +161,10 @@
     insert into content_ctags (id, name, kind, line, lang, indexer_configuration_id)
     select id, name, kind, line, lang, indexer_configuration_id
     from tmp_content_ctags tct
-        on conflict(id, hash_sha1(name), kind, line, lang, indexer_configuration_id)
-        do nothing;
-    return;
+    on conflict(id, hash_sha1(name), kind, line, lang, indexer_configuration_id)
+    do nothing;
+    get diagnostics res = ROW_COUNT;
+    return res;
 end
 $$;
 
@@ -217,9 +224,11 @@
 -- operates in bulk: 0. swh_mktemp(content_fossology_license), 1. COPY to
 -- tmp_content_fossology_license, 2. call this function
 create or replace function swh_content_fossology_license_add(conflict_update boolean)
-    returns void
-    language plpgsql
+  returns bigint
+  language plpgsql
 as $$
+declare
+  res bigint;
 begin
     -- insert unknown licenses first
     insert into fossology_license (name)
@@ -233,9 +242,8 @@
               (select id from fossology_license where name = tcl.license) as license,
               indexer_configuration_id
         from tmp_content_fossology_license tcl
-            on conflict(id, license_id, indexer_configuration_id)
-            do update set license_id = excluded.license_id;
-        return;
+        on conflict(id, license_id, indexer_configuration_id)
+        do update set license_id = excluded.license_id;
     end if;
 
     insert into content_fossology_license (id, license_id, indexer_configuration_id)
@@ -243,14 +251,17 @@
           (select id from fossology_license where name = tcl.license) as license,
           indexer_configuration_id
     from tmp_content_fossology_license tcl
-        on conflict(id, license_id, indexer_configuration_id)
-        do nothing;
-    return;
+    on conflict(id, license_id, indexer_configuration_id)
+    do nothing;
+
+    get diagnostics res = ROW_COUNT;
+    return res;
 end
 $$;
 
 comment on function swh_content_fossology_license_add(boolean) IS 'Add new content licenses';
 
+
 -- content_metadata functions
 
 -- add tmp_content_metadata entries to content_metadata, overwriting
@@ -263,25 +274,27 @@
 -- operates in bulk: 0. swh_mktemp(content_language), 1. COPY to
 -- tmp_content_metadata, 2. call this function
 create or replace function swh_content_metadata_add(conflict_update boolean)
-    returns void
+    returns bigint
     language plpgsql
 as $$
+declare
+  res bigint;
 begin
     if conflict_update then
       insert into content_metadata (id, metadata, indexer_configuration_id)
       select id, metadata, indexer_configuration_id
-    	from tmp_content_metadata tcm
-            on conflict(id, indexer_configuration_id)
-                do update set metadata = excluded.metadata;
-
+      from tmp_content_metadata tcm
+      on conflict(id, indexer_configuration_id)
+      do update set metadata = excluded.metadata;
     else
         insert into content_metadata (id, metadata, indexer_configuration_id)
         select id, metadata, indexer_configuration_id
     	from tmp_content_metadata tcm
-            on conflict(id, indexer_configuration_id)
-            do nothing;
+        on conflict(id, indexer_configuration_id)
+        do nothing;
     end if;
-    return;
+    get diagnostics res = ROW_COUNT;
+    return res;
 end
 $$;
 
@@ -312,27 +325,29 @@
 -- operates in bulk: 0. swh_mktemp(content_language), 1. COPY to
 -- tmp_revision_intrinsic_metadata, 2. call this function
 create or replace function swh_revision_intrinsic_metadata_add(conflict_update boolean)
-    returns void
+    returns bigint
     language plpgsql
 as $$
+declare
+  res bigint;
 begin
     if conflict_update then
       insert into revision_intrinsic_metadata (id, metadata, mappings, indexer_configuration_id)
       select id, metadata, mappings, indexer_configuration_id
-    	from tmp_revision_intrinsic_metadata tcm
-            on conflict(id, indexer_configuration_id)
-                do update set
-                    metadata = excluded.metadata,
-                    mappings = excluded.mappings;
-
+      from tmp_revision_intrinsic_metadata tcm
+      on conflict(id, indexer_configuration_id)
+      do update set
+          metadata = excluded.metadata,
+          mappings = excluded.mappings;
     else
         insert into revision_intrinsic_metadata (id, metadata, mappings, indexer_configuration_id)
         select id, metadata, mappings, indexer_configuration_id
     	from tmp_revision_intrinsic_metadata tcm
-            on conflict(id, indexer_configuration_id)
-            do nothing;
+        on conflict(id, indexer_configuration_id)
+        do nothing;
     end if;
-    return;
+    get diagnostics res = ROW_COUNT;
+    return res;
 end
 $$;
 
@@ -408,32 +423,34 @@
 -- tmp_origin_intrinsic_metadata, 2. call this function
 create or replace function swh_origin_intrinsic_metadata_add(
         conflict_update boolean)
-    returns void
+    returns bigint
     language plpgsql
 as $$
+declare
+  res bigint;
 begin
     perform swh_origin_intrinsic_metadata_compute_tsvector();
     if conflict_update then
       insert into origin_intrinsic_metadata (id, metadata, indexer_configuration_id, from_revision, metadata_tsvector, mappings)
       select id, metadata, indexer_configuration_id, from_revision,
              metadata_tsvector, mappings
-    	from tmp_origin_intrinsic_metadata
-            on conflict(id, indexer_configuration_id)
-                do update set
-                    metadata = excluded.metadata,
-                    metadata_tsvector = excluded.metadata_tsvector,
-                    mappings = excluded.mappings,
-                    from_revision = excluded.from_revision;
-
+      from tmp_origin_intrinsic_metadata
+      on conflict(id, indexer_configuration_id)
+      do update set
+          metadata = excluded.metadata,
+          metadata_tsvector = excluded.metadata_tsvector,
+          mappings = excluded.mappings,
+          from_revision = excluded.from_revision;
     else
         insert into origin_intrinsic_metadata (id, metadata, indexer_configuration_id, from_revision, metadata_tsvector, mappings)
         select id, metadata, indexer_configuration_id, from_revision,
                metadata_tsvector, mappings
     	from tmp_origin_intrinsic_metadata
-            on conflict(id, indexer_configuration_id)
-            do nothing;
+        on conflict(id, indexer_configuration_id)
+        do nothing;
     end if;
-    return;
+    get diagnostics res = ROW_COUNT;
+    return res;
 end
 $$;
 
diff --git a/swh/indexer/storage/__init__.py b/swh/indexer/storage/__init__.py
--- a/swh/indexer/storage/__init__.py
+++ b/swh/indexer/storage/__init__.py
@@ -9,9 +9,11 @@
 import psycopg2.pool
 
 from collections import defaultdict, Counter
+from typing import Dict, List
 
 from swh.storage.common import db_transaction_generator, db_transaction
 from swh.storage.exc import StorageDBError
+from swh.storage.metrics import send_metric, timed, process_metrics
 
 from . import converters
 from .db import Db
@@ -165,16 +167,31 @@
                                        indexer_configuration_id, limit=limit,
                                        db=db, cur=cur)
 
+    @timed
+    @process_metrics
     @db_transaction()
-    def content_mimetype_add(self, mimetypes, conflict_update=False, db=None,
-                             cur=None):
+    def content_mimetype_add(
+            self, mimetypes: List[Dict], conflict_update: bool = False,
+            db=None, cur=None) -> Dict:
+        """Add mimetypes to the storage (if conflict_update is True, this will
+           override existing data if any).
+
+        Returns:
+            A dict with the number of new elements added to the storage.
+
+        """
         check_id_duplicates(mimetypes)
         mimetypes.sort(key=lambda m: m['id'])
         db.mktemp_content_mimetype(cur)
         db.copy_to(mimetypes, 'tmp_content_mimetype',
                    ['id', 'mimetype', 'encoding', 'indexer_configuration_id'],
                    cur)
-        db.content_mimetype_add_from_temp(conflict_update, cur)
+        count = db.content_mimetype_add_from_temp(conflict_update, cur)
+        send_metric('content_mimetype:add',
+                    count=count, method_name='content_mimetype_add')
+        return {
+            'content_mimetype:add': count
+        }
 
     @db_transaction_generator()
     def content_mimetype_get(self, ids, db=None, cur=None):
@@ -193,9 +210,12 @@
             yield converters.db_to_language(
                 dict(zip(db.content_language_cols, c)))
 
+    @timed
+    @process_metrics
     @db_transaction()
-    def content_language_add(self, languages, conflict_update=False, db=None,
-                             cur=None):
+    def content_language_add(
+            self, languages: List[Dict],
+            conflict_update: bool = False, db=None, cur=None) -> Dict:
         check_id_duplicates(languages)
         languages.sort(key=lambda m: m['id'])
         db.mktemp_content_language(cur)
@@ -209,7 +229,12 @@
             'tmp_content_language',
             ['id', 'lang', 'indexer_configuration_id'], cur)
 
-        db.content_language_add_from_temp(conflict_update, cur)
+        count = db.content_language_add_from_temp(conflict_update, cur)
+        send_metric('content_language:add',
+                    count=count, method_name='content_language_add')
+        return {
+            'content_language:add': count
+        }
 
     @db_transaction_generator()
     def content_ctags_missing(self, ctags, db=None, cur=None):
@@ -221,9 +246,12 @@
         for c in db.content_ctags_get_from_list(ids, cur):
             yield converters.db_to_ctags(dict(zip(db.content_ctags_cols, c)))
 
+    @timed
+    @process_metrics
     @db_transaction()
-    def content_ctags_add(self, ctags, conflict_update=False, db=None,
-                          cur=None):
+    def content_ctags_add(
+            self, ctags: List[Dict], conflict_update: bool = False,
+            db=None, cur=None) -> Dict:
         check_id_duplicates(ctags)
         ctags.sort(key=lambda m: m['id'])
 
@@ -241,7 +269,12 @@
                             'lang', 'indexer_configuration_id'],
                    cur=cur)
 
-        db.content_ctags_add_from_temp(conflict_update, cur)
+        count = db.content_ctags_add_from_temp(conflict_update, cur)
+        send_metric('content_ctags:add',
+                    count=count, method_name='content_ctags_add')
+        return {
+            'content_ctags:add': count
+        }
 
     @db_transaction_generator()
     def content_ctags_search(self, expression,
@@ -262,9 +295,12 @@
         for id_, facts in d.items():
             yield {id_: facts}
 
+    @timed
+    @process_metrics
     @db_transaction()
-    def content_fossology_license_add(self, licenses, conflict_update=False,
-                                      db=None, cur=None):
+    def content_fossology_license_add(
+            self, licenses: List[Dict], conflict_update: bool = False,
+            db=None, cur=None) -> Dict:
         check_id_duplicates(licenses)
         licenses.sort(key=lambda m: m['id'])
         db.mktemp_content_fossology_license(cur)
@@ -278,7 +314,13 @@
             tblname='tmp_content_fossology_license',
             columns=['id', 'license', 'indexer_configuration_id'],
             cur=cur)
-        db.content_fossology_license_add_from_temp(conflict_update, cur)
+        count = db.content_fossology_license_add_from_temp(
+            conflict_update, cur)
+        send_metric('content_fossology_license:add',
+                    count=count, method_name='content_fossology_license_add')
+        return {
+            'content_fossology_license:add': count
+        }
 
     @db_transaction()
     def content_fossology_license_get_range(
@@ -299,9 +341,12 @@
             yield converters.db_to_metadata(
                 dict(zip(db.content_metadata_cols, c)))
 
+    @timed
+    @process_metrics
     @db_transaction()
-    def content_metadata_add(self, metadata, conflict_update=False, db=None,
-                             cur=None):
+    def content_metadata_add(
+            self, metadata: List[Dict], conflict_update: bool = False,
+            db=None, cur=None) -> Dict:
         check_id_duplicates(metadata)
         metadata.sort(key=lambda m: m['id'])
 
@@ -310,7 +355,12 @@
         db.copy_to(metadata, 'tmp_content_metadata',
                    ['id', 'metadata', 'indexer_configuration_id'],
                    cur)
-        db.content_metadata_add_from_temp(conflict_update, cur)
+        count = db.content_metadata_add_from_temp(conflict_update, cur)
+        send_metric('content_metadata:add',
+                    count=count, method_name='content_metadata_add')
+        return {
+            'content_metadata:add': count,
+        }
 
     @db_transaction_generator()
     def revision_intrinsic_metadata_missing(self, metadata, db=None, cur=None):
@@ -324,9 +374,12 @@
             yield converters.db_to_metadata(
                 dict(zip(db.revision_intrinsic_metadata_cols, c)))
 
+    @timed
+    @process_metrics
     @db_transaction()
-    def revision_intrinsic_metadata_add(self, metadata, conflict_update=False,
-                                        db=None, cur=None):
+    def revision_intrinsic_metadata_add(
+            self, metadata: List[Dict], conflict_update: bool = False,
+            db=None, cur=None) -> Dict:
         check_id_duplicates(metadata)
         metadata.sort(key=lambda m: m['id'])
 
@@ -336,11 +389,23 @@
                    ['id', 'metadata', 'mappings',
                     'indexer_configuration_id'],
                    cur)
-        db.revision_intrinsic_metadata_add_from_temp(conflict_update, cur)
+        count = db.revision_intrinsic_metadata_add_from_temp(
+            conflict_update, cur)
+        send_metric('revision_intrinsic_metadata:add',
+                    count=count, method_name='revision_intrinsic_metadata_add')
+        return {
+            'revision_intrinsic_metadata:add': count,
+        }
 
+    @timed
+    @process_metrics
     @db_transaction()
-    def revision_intrinsic_metadata_delete(self, entries, db=None, cur=None):
-        db.revision_intrinsic_metadata_delete(entries, cur)
+    def revision_intrinsic_metadata_delete(
+            self, entries: List[Dict], db=None, cur=None) -> Dict:
+        count = db.revision_intrinsic_metadata_delete(entries, cur)
+        return {
+            'revision_intrinsic_metadata:del': count
+        }
 
     @db_transaction_generator()
     def origin_intrinsic_metadata_get(self, ids, db=None, cur=None):
@@ -348,10 +413,12 @@
             yield converters.db_to_metadata(
                 dict(zip(db.origin_intrinsic_metadata_cols, c)))
 
+    @timed
+    @process_metrics
     @db_transaction()
-    def origin_intrinsic_metadata_add(self, metadata,
-                                      conflict_update=False, db=None,
-                                      cur=None):
+    def origin_intrinsic_metadata_add(
+            self, metadata: List[Dict], conflict_update: bool = False,
+            db=None, cur=None) -> Dict:
         check_id_duplicates(metadata)
         metadata.sort(key=lambda m: m['id'])
 
@@ -362,12 +429,23 @@
                     'indexer_configuration_id',
                     'from_revision', 'mappings'],
                    cur)
-        db.origin_intrinsic_metadata_add_from_temp(conflict_update, cur)
+        count = db.origin_intrinsic_metadata_add_from_temp(
+            conflict_update, cur)
+        send_metric('content_origin_intrinsic:add',
+                    count=count, method_name='content_origin_intrinsic_add')
+        return {
+            'origin_intrinsic_metadata:add': count,
+        }
 
+    @timed
+    @process_metrics
     @db_transaction()
     def origin_intrinsic_metadata_delete(
-            self, entries, db=None, cur=None):
-        db.origin_intrinsic_metadata_delete(entries, cur)
+            self, entries: List[Dict], db=None, cur=None) -> Dict:
+        count = db.origin_intrinsic_metadata_delete(entries, cur)
+        return {
+            'origin_intrinsic_metadata:del': count,
+        }
 
     @db_transaction_generator()
     def origin_intrinsic_metadata_search_fulltext(
diff --git a/swh/indexer/storage/db.py b/swh/indexer/storage/db.py
--- a/swh/indexer/storage/db.py
+++ b/swh/indexer/storage/db.py
@@ -60,8 +60,10 @@
     def mktemp_content_mimetype(self, cur=None): pass
 
     def content_mimetype_add_from_temp(self, conflict_update, cur=None):
-        self._cursor(cur).execute("SELECT swh_content_mimetype_add(%s)",
-                                  (conflict_update, ))
+        cur = self._cursor(cur)
+        cur.execute('select * from swh_content_mimetype_add(%s)',
+                    (conflict_update, ))
+        return cur.fetchone()[0]
 
     def _convert_key(self, key, main_table='c'):
         """Convert keys according to specific use in the module.
@@ -176,8 +178,10 @@
     def mktemp_content_language(self, cur=None): pass
 
     def content_language_add_from_temp(self, conflict_update, cur=None):
-        self._cursor(cur).execute("SELECT swh_content_language_add(%s)",
-                                  (conflict_update, ))
+        cur = self._cursor(cur)
+        cur.execute('select * from swh_content_language_add(%s)',
+                    (conflict_update, ))
+        return cur.fetchone()[0]
 
     def content_language_get_from_list(self, ids, cur=None):
         yield from self._get_from_list(
@@ -201,8 +205,11 @@
     def mktemp_content_ctags(self, cur=None): pass
 
     def content_ctags_add_from_temp(self, conflict_update, cur=None):
-        self._cursor(cur).execute("SELECT swh_content_ctags_add(%s)",
-                                  (conflict_update, ))
+        cur = self._cursor(cur)
+        cur.execute(
+            'select * from swh_content_ctags_add(%s)',
+            (conflict_update, ))
+        return cur.fetchone()[0]
 
     def content_ctags_get_from_list(self, ids, cur=None):
         cur = self._cursor(cur)
@@ -252,9 +259,11 @@
         """Add new licenses per content.
 
         """
-        self._cursor(cur).execute(
-            "SELECT swh_content_fossology_license_add(%s)",
+        cur = self._cursor(cur)
+        cur.execute(
+            'select * from swh_content_fossology_license_add(%s)',
             (conflict_update, ))
+        return cur.fetchone()[0]
 
     def content_fossology_license_get_from_list(self, ids, cur=None):
         """Retrieve licenses per id.
@@ -293,8 +302,11 @@
     def mktemp_content_metadata(self, cur=None): pass
 
     def content_metadata_add_from_temp(self, conflict_update, cur=None):
-        self._cursor(cur).execute("SELECT swh_content_metadata_add(%s)",
-                                  (conflict_update, ))
+        cur = self._cursor(cur)
+        cur.execute(
+            'select * from swh_content_metadata_add(%s)',
+            (conflict_update, ))
+        return cur.fetchone()[0]
 
     def content_metadata_get_from_list(self, ids, cur=None):
         yield from self._get_from_list(
@@ -321,9 +333,11 @@
 
     def revision_intrinsic_metadata_add_from_temp(
             self, conflict_update, cur=None):
-        self._cursor(cur).execute(
-                "SELECT swh_revision_intrinsic_metadata_add(%s)",
-                (conflict_update, ))
+        cur = self._cursor(cur)
+        cur.execute(
+            'select * from swh_revision_intrinsic_metadata_add(%s)',
+            (conflict_update, ))
+        return cur.fetchone()[0]
 
     def revision_intrinsic_metadata_delete(
             self, entries, cur=None):
@@ -331,9 +345,11 @@
         cur.execute(
                 "DELETE from revision_intrinsic_metadata "
                 "WHERE (id, indexer_configuration_id) IN "
-                "   (VALUES %s)" % (', '.join('%s' for _ in entries)),
+                "   (VALUES %s) "
+                "RETURNING id" % (', '.join('%s' for _ in entries)),
                 tuple((e['id'], e['indexer_configuration_id'])
                       for e in entries),)
+        return len(cur.fetchall())
 
     def revision_intrinsic_metadata_get_from_list(self, ids, cur=None):
         yield from self._get_from_list(
@@ -358,8 +374,9 @@
             self, conflict_update, cur=None):
         cur = self._cursor(cur)
         cur.execute(
-                "SELECT swh_origin_intrinsic_metadata_add(%s)",
-                (conflict_update, ))
+            'select * from swh_origin_intrinsic_metadata_add(%s)',
+            (conflict_update, ))
+        return cur.fetchone()[0]
 
     def origin_intrinsic_metadata_delete(
             self, entries, cur=None):
@@ -367,9 +384,11 @@
         cur.execute(
                 "DELETE from origin_intrinsic_metadata "
                 "WHERE (id, indexer_configuration_id) IN"
-                "   (VALUES %s)" % (', '.join('%s' for _ in entries)),
+                "   (VALUES %s) "
+                "RETURNING id" % (', '.join('%s' for _ in entries)),
                 tuple((e['id'], e['indexer_configuration_id'])
                       for e in entries),)
+        return len(cur.fetchall())
 
     def origin_intrinsic_metadata_get_from_list(self, ids, cur=None):
         yield from self._get_from_list(
diff --git a/swh/indexer/storage/in_memory.py b/swh/indexer/storage/in_memory.py
--- a/swh/indexer/storage/in_memory.py
+++ b/swh/indexer/storage/in_memory.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2018  The Software Heritage developers
+# Copyright (C) 2018-2020  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
@@ -123,7 +123,7 @@
                 'next': None,
                 }
 
-    def add(self, data, conflict_update):
+    def add(self, data: List[Dict], conflict_update: bool) -> int:
         """Add data not present in storage.
 
         Args:
@@ -140,22 +140,27 @@
         """
         data = list(data)
         check_id_duplicates(data)
+        count = 0
         for item in data:
             item = item.copy()
             tool_id = item.pop('indexer_configuration_id')
             id_ = item.pop('id')
-            data = item
+            data_item = item
             if not conflict_update and \
                     tool_id in self._tools_per_id.get(id_, set()):
                 # Duplicate, should not be updated
                 continue
             key = (id_, tool_id)
-            self._data[key] = data
+            self._data[key] = data_item
             self._tools_per_id[id_].add(tool_id)
+            count += 1
             if id_ not in self._sorted_ids:
                 bisect.insort(self._sorted_ids, id_)
+        return count
 
-    def add_merge(self, new_data, conflict_update, merged_key):
+    def add_merge(self, new_data: List[Dict], conflict_update: bool,
+                  merged_key: str) -> int:
+        added = 0
         for new_item in new_data:
             id_ = new_item['id']
             tool_id = new_item['indexer_configuration_id']
@@ -172,7 +177,7 @@
             for new_subitem in new_item[merged_key]:
                 if new_subitem not in all_subitems:
                     all_subitems.append(new_subitem)
-            self.add([
+            added += self.add([
                 {
                     'id': id_,
                     'indexer_configuration_id': tool_id,
@@ -181,15 +186,22 @@
             ], conflict_update=True)
             if id_ not in self._sorted_ids:
                 bisect.insort(self._sorted_ids, id_)
+        return added
 
-    def delete(self, entries):
+    def delete(self, entries: List[Dict]) -> int:
+        """Delete entries and return the number of entries deleted.
+
+        """
+        deleted = 0
         for entry in entries:
             (id_, tool_id) = (entry['id'], entry['indexer_configuration_id'])
             key = (id_, tool_id)
             if tool_id in self._tools_per_id[id_]:
                 self._tools_per_id[id_].remove(tool_id)
             if key in self._data:
+                deleted += 1
                 del self._data[key]
+        return deleted
 
 
 class IndexerStorage:
@@ -216,9 +228,12 @@
         return self._mimetypes.get_range(
             start, end, indexer_configuration_id, limit)
 
-    def content_mimetype_add(self, mimetypes, conflict_update=False):
+    def content_mimetype_add(
+            self, mimetypes: List[Dict],
+            conflict_update: bool = False) -> Dict:
         check_id_types(mimetypes)
-        self._mimetypes.add(mimetypes, conflict_update)
+        added = self._mimetypes.add(mimetypes, conflict_update)
+        return {'content_mimetype:add': added}
 
     def content_mimetype_get(self, ids):
         yield from self._mimetypes.get(ids)
@@ -229,9 +244,12 @@
     def content_language_get(self, ids):
         yield from self._languages.get(ids)
 
-    def content_language_add(self, languages, conflict_update=False):
+    def content_language_add(
+            self, languages: List[Dict],
+            conflict_update: bool = False) -> Dict:
         check_id_types(languages)
-        self._languages.add(languages, conflict_update)
+        added = self._languages.add(languages, conflict_update)
+        return {'content_language:add': added}
 
     def content_ctags_missing(self, ctags):
         yield from self._content_ctags.missing(ctags)
@@ -245,9 +263,11 @@
                     **item_ctags_item
                 }
 
-    def content_ctags_add(self, ctags, conflict_update=False):
+    def content_ctags_add(
+            self, ctags: List[Dict], conflict_update: bool = False) -> Dict:
         check_id_types(ctags)
-        self._content_ctags.add_merge(ctags, conflict_update, 'ctags')
+        added = self._content_ctags.add_merge(ctags, conflict_update, 'ctags')
+        return {'content_ctags:add': added}
 
     def content_ctags_search(self, expression,
                              limit=10, last_sha1=None):
@@ -279,9 +299,11 @@
         for (id_, facts) in res.items():
             yield {id_: facts}
 
-    def content_fossology_license_add(self, licenses, conflict_update=False):
+    def content_fossology_license_add(
+            self, licenses: List[Dict], conflict_update: bool = False) -> Dict:
         check_id_types(licenses)
-        self._licenses.add_merge(licenses, conflict_update, 'licenses')
+        added = self._licenses.add_merge(licenses, conflict_update, 'licenses')
+        return {'fossology_license_add:add': added}
 
     def content_fossology_license_get_range(
             self, start, end, indexer_configuration_id, limit=1000):
@@ -294,9 +316,11 @@
     def content_metadata_get(self, ids):
         yield from self._content_metadata.get(ids)
 
-    def content_metadata_add(self, metadata, conflict_update=False):
+    def content_metadata_add(
+            self, metadata: List[Dict], conflict_update: bool = False) -> Dict:
         check_id_types(metadata)
-        self._content_metadata.add(metadata, conflict_update)
+        added = self._content_metadata.add(metadata, conflict_update)
+        return {'content_metadata:add': added}
 
     def revision_intrinsic_metadata_missing(self, metadata):
         yield from self._revision_intrinsic_metadata.missing(metadata)
@@ -304,22 +328,28 @@
     def revision_intrinsic_metadata_get(self, ids):
         yield from self._revision_intrinsic_metadata.get(ids)
 
-    def revision_intrinsic_metadata_add(self, metadata, conflict_update=False):
+    def revision_intrinsic_metadata_add(
+            self, metadata: List[Dict], conflict_update: bool = False) -> Dict:
         check_id_types(metadata)
-        self._revision_intrinsic_metadata.add(metadata, conflict_update)
+        added = self._revision_intrinsic_metadata.add(
+            metadata, conflict_update)
+        return {'revision_intrinsic_metadata:add': added}
 
-    def revision_intrinsic_metadata_delete(self, entries):
-        self._revision_intrinsic_metadata.delete(entries)
+    def revision_intrinsic_metadata_delete(self, entries: List[Dict]) -> Dict:
+        deleted = self._revision_intrinsic_metadata.delete(entries)
+        return {'revision_intrinsic_metadata:del': deleted}
 
     def origin_intrinsic_metadata_get(self, ids):
         yield from self._origin_intrinsic_metadata.get(ids)
 
-    def origin_intrinsic_metadata_add(self, metadata,
-                                      conflict_update=False):
-        self._origin_intrinsic_metadata.add(metadata, conflict_update)
+    def origin_intrinsic_metadata_add(
+            self, metadata: List[Dict], conflict_update: bool = False) -> Dict:
+        added = self._origin_intrinsic_metadata.add(metadata, conflict_update)
+        return {'origin_intrinsic_metadata:add': added}
 
-    def origin_intrinsic_metadata_delete(self, entries):
-        self._origin_intrinsic_metadata.delete(entries)
+    def origin_intrinsic_metadata_delete(self, entries: List[Dict]) -> Dict:
+        deleted = self._origin_intrinsic_metadata.delete(entries)
+        return {'origin_intrinsic_metadata:del': deleted}
 
     def origin_intrinsic_metadata_search_fulltext(
             self, conjunction, limit=100):
diff --git a/swh/indexer/storage/interface.py b/swh/indexer/storage/interface.py
--- a/swh/indexer/storage/interface.py
+++ b/swh/indexer/storage/interface.py
@@ -3,6 +3,7 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+from typing import Dict, List
 
 from swh.core.api import remote_api_endpoint
 
@@ -89,7 +90,8 @@
         ...
 
     @remote_api_endpoint('content_mimetype/add')
-    def content_mimetype_add(self, mimetypes, conflict_update=False):
+    def content_mimetype_add(self, mimetypes: List[Dict],
+                             conflict_update: bool = False) -> Dict:
         """Add mimetypes not present in storage.
 
         Args:
@@ -104,6 +106,9 @@
                 overwrite (``True``) or skip duplicates (``False``, the
                 default)
 
+        Returns:
+            Dict summary of number of rows added
+
         """
         ...
 
@@ -161,7 +166,9 @@
         ...
 
     @remote_api_endpoint('content_language/add')
-    def content_language_add(self, languages, conflict_update=False):
+    def content_language_add(
+            self, languages: List[Dict],
+            conflict_update: bool = False) -> Dict:
         """Add languages not present in storage.
 
         Args:
@@ -174,6 +181,9 @@
                 overwrite (true) or skip duplicates (false, the
                 default)
 
+        Returns:
+            Dict summary of number of rows added
+
         """
         ...
 
@@ -216,7 +226,8 @@
         ...
 
     @remote_api_endpoint('content/ctags/add')
-    def content_ctags_add(self, ctags, conflict_update=False):
+    def content_ctags_add(self, ctags: List[Dict],
+                          conflict_update: bool = False) -> Dict:
         """Add ctags not present in storage
 
         Args:
@@ -226,6 +237,9 @@
                 - **ctags** ([list): List of dictionary with keys: name, kind,
                   line, lang
 
+        Returns:
+            Dict summary of number of rows added
+
         """
         ...
 
@@ -263,7 +277,8 @@
         ...
 
     @remote_api_endpoint('content/fossology_license/add')
-    def content_fossology_license_add(self, licenses, conflict_update=False):
+    def content_fossology_license_add(
+            self, licenses: List[Dict], conflict_update: bool = False) -> Dict:
         """Add licenses not present in storage.
 
         Args:
@@ -277,7 +292,7 @@
                 or skip duplicates (false, the default)
 
         Returns:
-            list: content_license entries which failed due to unknown licenses
+            Dict summary of number of rows added
 
         """
         ...
@@ -343,7 +358,8 @@
         ...
 
     @remote_api_endpoint('content_metadata/add')
-    def content_metadata_add(self, metadata, conflict_update=False):
+    def content_metadata_add(
+            self, metadata: List[Dict], conflict_update: bool = False) -> Dict:
         """Add metadata not present in storage.
 
         Args:
@@ -355,6 +371,9 @@
             conflict_update: Flag to determine if we want to overwrite (true)
                 or skip duplicates (false, the default)
 
+        Returns:
+            Dict summary of number of rows added
+
         """
         ...
 
@@ -395,7 +414,8 @@
         ...
 
     @remote_api_endpoint('revision_intrinsic_metadata/add')
-    def revision_intrinsic_metadata_add(self, metadata, conflict_update=False):
+    def revision_intrinsic_metadata_add(
+            self, metadata: List[Dict], conflict_update: bool = False) -> Dict:
         """Add metadata not present in storage.
 
         Args:
@@ -410,11 +430,14 @@
             conflict_update: Flag to determine if we want to overwrite (true)
               or skip duplicates (false, the default)
 
+        Returns:
+            Dict summary of number of rows added
+
         """
         ...
 
     @remote_api_endpoint('revision_intrinsic_metadata/delete')
-    def revision_intrinsic_metadata_delete(self, entries):
+    def revision_intrinsic_metadata_delete(self, entries: List[Dict]) -> Dict:
         """Remove revision metadata from the storage.
 
         Args:
@@ -423,6 +446,9 @@
                 - **id** (bytes): revision identifier
                 - **indexer_configuration_id** (int): tool used to compute
                   metadata
+
+        Returns:
+            Summary of number of rows deleted
         """
         ...
 
@@ -448,8 +474,8 @@
         ...
 
     @remote_api_endpoint('origin_intrinsic_metadata/add')
-    def origin_intrinsic_metadata_add(self, metadata,
-                                      conflict_update=False):
+    def origin_intrinsic_metadata_add(
+            self, metadata: List[Dict], conflict_update: bool = False) -> Dict:
         """Add origin metadata not present in storage.
 
         Args:
@@ -466,12 +492,15 @@
             conflict_update: Flag to determine if we want to overwrite (true)
               or skip duplicates (false, the default)
 
+        Returns:
+            Dict summary of number of rows added
+
         """
         ...
 
     @remote_api_endpoint('origin_intrinsic_metadata/delete')
     def origin_intrinsic_metadata_delete(
-            self, entries):
+            self, entries: List[Dict]) -> Dict:
         """Remove origin metadata from the storage.
 
         Args:
@@ -480,6 +509,9 @@
                 - **id** (str): origin urls
                 - **indexer_configuration_id** (int): tool used to compute
                   metadata
+
+        Returns:
+            Summary of number of rows deleted
         """
         ...
 
diff --git a/swh/indexer/storage/metrics.py b/swh/indexer/storage/metrics.py
new file mode 100644
--- /dev/null
+++ b/swh/indexer/storage/metrics.py
@@ -0,0 +1,79 @@
+# Copyright (C) 2019-2020  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 functools import wraps
+import logging
+
+from swh.core.statsd import statsd
+
+OPERATIONS_METRIC = 'swh_indexer_storage_operations_total'
+OPERATIONS_UNIT_METRIC = "swh_indexer_storage_operations_{unit}_total"
+DURATION_METRIC = "swh_indexer_storage_request_duration_seconds"
+
+
+def timed(f):
+    """Time that function!
+
+    """
+    @wraps(f)
+    def d(*a, **kw):
+        with statsd.timed(DURATION_METRIC, tags={'endpoint': f.__name__}):
+            return f(*a, **kw)
+
+    return d
+
+
+def send_metric(metric, count, method_name):
+    """Send statsd metric with count for method `method_name`
+
+    If count is 0, the metric is discarded.  If the metric is not
+    parseable, the metric is discarded with a log message.
+
+    Args:
+        metric (str): Metric's name (e.g content:add, content:add:bytes)
+        count (int): Associated value for the metric
+        method_name (str): Method's name
+
+    Returns:
+        Bool to explicit if metric has been set or not
+    """
+    if count == 0:
+        return False
+
+    metric_type = metric.split(':')
+    _length = len(metric_type)
+    if _length == 2:
+        object_type, operation = metric_type
+        metric_name = OPERATIONS_METRIC
+    elif _length == 3:
+        object_type, operation, unit = metric_type
+        metric_name = OPERATIONS_UNIT_METRIC.format(unit=unit)
+    else:
+        logging.warning('Skipping unknown metric {%s: %s}' % (
+            metric, count))
+        return False
+
+    statsd.increment(
+        metric_name, count, tags={
+            'endpoint': method_name,
+            'object_type': object_type,
+            'operation': operation,
+        })
+    return True
+
+
+def process_metrics(f):
+    """Increment object counters for the decorated function.
+
+    """
+    @wraps(f)
+    def d(*a, **kw):
+        r = f(*a, **kw)
+        for metric, count in r.items():
+            send_metric(metric=metric, count=count, method_name=f.__name__)
+
+        return r
+
+    return d
diff --git a/swh/indexer/tasks.py b/swh/indexer/tasks.py
--- a/swh/indexer/tasks.py
+++ b/swh/indexer/tasks.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2016-2019  The Software Heritage developers
+# Copyright (C) 2016-2020  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
@@ -17,41 +17,34 @@
 
 @app.task(name=__name__ + '.OriginMetadata')
 def origin_metadata(*args, **kwargs):
-    results = OriginMetadataIndexer().run(*args, **kwargs)
-    return getattr(results, 'results', results)
+    return OriginMetadataIndexer().run(*args, **kwargs)
 
 
 @app.task(name=__name__ + '.Ctags')
 def ctags(*args, **kwargs):
-    results = CtagsIndexer().run(*args, **kwargs)
-    return getattr(results, 'results', results)
+    return CtagsIndexer().run(*args, **kwargs)
 
 
 @app.task(name=__name__ + '.ContentFossologyLicense')
 def fossology_license(*args, **kwargs):
-    results = FossologyLicenseIndexer().run(*args, **kwargs)
-    return getattr(results, 'results', results)
+    return FossologyLicenseIndexer().run(*args, **kwargs)
 
 
 @app.task(name=__name__ + '.RecomputeChecksums')
 def recompute_checksums(*args, **kwargs):
-    results = RecomputeChecksums().run(*args, **kwargs)
-    return getattr(results, 'results', results)
+    return RecomputeChecksums().run(*args, **kwargs)
 
 
 @app.task(name=__name__ + '.ContentMimetype')
 def mimetype(*args, **kwargs):
-    results = MimetypeIndexer().run(*args, **kwargs)
-    return {'status': 'eventful' if results else 'uneventful'}
+    return MimetypeIndexer().run(*args, **kwargs)
 
 
 @app.task(name=__name__ + '.ContentRangeMimetype')
 def range_mimetype(*args, **kwargs):
-    results = MimetypeRangeIndexer().run(*args, **kwargs)
-    return {'status': 'eventful' if results else 'uneventful'}
+    return MimetypeRangeIndexer().run(*args, **kwargs)
 
 
 @app.task(name=__name__ + '.ContentRangeFossologyLicense')
 def range_license(*args, **kwargs):
-    results = FossologyLicenseRangeIndexer().run(*args, **kwargs)
-    return {'status': 'eventful' if results else 'uneventful'}
+    return FossologyLicenseRangeIndexer().run(*args, **kwargs)
diff --git a/swh/indexer/tests/storage/test_metrics.py b/swh/indexer/tests/storage/test_metrics.py
new file mode 100644
--- /dev/null
+++ b/swh/indexer/tests/storage/test_metrics.py
@@ -0,0 +1,53 @@
+# Copyright (C) 2019-2020  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 unittest.mock import patch
+
+from swh.indexer.storage.metrics import (
+    send_metric, OPERATIONS_METRIC, OPERATIONS_UNIT_METRIC
+)
+
+
+def test_send_metric_unknown_unit():
+    r = send_metric('content', count=10, method_name='content_add')
+    assert r is False
+    r = send_metric('sthg:add:bytes:extra', count=10, method_name='sthg_add')
+    assert r is False
+
+
+def test_send_metric_no_value():
+    r = send_metric('content_mimetype:add', count=0,
+                    method_name='content_mimetype_add')
+    assert r is False
+
+
+@patch('swh.indexer.storage.metrics.statsd.increment')
+def test_send_metric_no_unit(mock_statsd):
+    r = send_metric('content_mimetype:add', count=10,
+                    method_name='content_mimetype_add')
+
+    mock_statsd.assert_called_with(OPERATIONS_METRIC, 10, tags={
+        'endpoint': 'content_mimetype_add',
+        'object_type': 'content_mimetype',
+        'operation': 'add',
+    })
+
+    assert r
+
+
+@patch('swh.indexer.storage.metrics.statsd.increment')
+def test_send_metric_unit(mock_statsd):
+    unit_ = 'bytes'
+    r = send_metric('c:add:%s' % unit_, count=100, method_name='c_add')
+
+    expected_metric = OPERATIONS_UNIT_METRIC.format(unit=unit_)
+    mock_statsd.assert_called_with(
+        expected_metric, 100, tags={
+            'endpoint': 'c_add',
+            'object_type': 'c',
+            'operation': 'add',
+        })
+
+    assert r
diff --git a/swh/indexer/tests/storage/test_storage.py b/swh/indexer/tests/storage/test_storage.py
--- a/swh/indexer/tests/storage/test_storage.py
+++ b/swh/indexer/tests/storage/test_storage.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2015-2019  The Software Heritage developers
+# Copyright (C) 2015-2020  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
@@ -6,6 +6,8 @@
 import inspect
 import threading
 
+from typing import Dict
+
 import pytest
 
 from swh.model.hashutil import hash_to_bytes
@@ -31,8 +33,39 @@
     return mimetypes
 
 
-def endpoint(storage, endpoint_type, endpoint_name):
-    return getattr(storage, endpoint_type + '_' + endpoint_name)
+def endpoint_name(etype: str, ename: str) -> str:
+    """Compute the storage's endpoint's name
+
+    >>> endpoint_name('content_mimetype', 'add')
+    'content_mimetype_add'
+    >>> endpoint_name('content_fosso_license', 'delete')
+    'content_fosso_license_delete'
+
+    """
+    return f'{etype}_{ename}'
+
+
+def endpoint(storage, etype: str, ename: str):
+    return getattr(storage, endpoint_name(etype, ename))
+
+
+def expected_summary(
+        count: int, etype: str, ename: str = 'add') -> Dict[str, int]:
+    """Compute the expected summary
+
+    The key is determine according to etype and ename
+
+        >>> expected_summary(10, 'content_mimetype', 'add')
+        {'content_mimetype:add': 10}
+        >>> expected_summary(9, 'origin_intrinsic_metadata', 'delete')
+        {'origin_intrinsic_metadata:del': 9}
+
+    """
+    pattern = ename[0:3]
+    key = endpoint_name(etype, ename).replace(f'_{ename}', f':{pattern}')
+    return {
+        key: count
+    }
 
 
 class StorageETypeTester:
@@ -71,12 +104,14 @@
         ]
 
         # now, when we add one of them
-        endpoint(storage, etype, 'add')([{
+        summary = endpoint(storage, etype, 'add')([{
             'id': data.sha1_2,
             **self.example_data[0],
             'indexer_configuration_id': tool_id,
         }])
 
+        assert summary == expected_summary(1, etype)
+
         # we expect only the other one returned
         actual_missing = endpoint(storage, etype, 'missing')(query)
         assert list(actual_missing) == [data.sha1_1]
@@ -92,7 +127,8 @@
             **self.example_data[0],
             'indexer_configuration_id': tool_id,
         }
-        endpoint(storage, etype, 'add')([data_v1])
+        summary = endpoint(storage, etype, 'add')([data_v1])
+        assert summary == expected_summary(1, etype)
 
         # should be able to retrieve it
         actual_data = list(endpoint(storage, etype, 'get')([data.sha1_2]))
@@ -106,7 +142,8 @@
         # now if we add a modified version of the same object (same id)
         data_v2 = data_v1.copy()
         data_v2.update(self.example_data[1])
-        endpoint(storage, etype, 'add')([data_v2])
+        summary2 = endpoint(storage, etype, 'add')([data_v2])
+        assert summary2 == expected_summary(0, etype)  # not added
 
         # we expect to retrieve the original data, not the modified one
         actual_data = list(endpoint(storage, etype, 'get')([data.sha1_2]))
@@ -125,7 +162,8 @@
         }
 
         # given
-        endpoint(storage, etype, 'add')([data_v1])
+        summary = endpoint(storage, etype, 'add')([data_v1])
+        assert summary == expected_summary(1, etype)  # not added
 
         # when
         actual_data = list(endpoint(storage, etype, 'get')([data.sha1_2]))
@@ -144,6 +182,7 @@
         data_v2.update(self.example_data[1])
 
         endpoint(storage, etype, 'add')([data_v2], conflict_update=True)
+        assert summary == expected_summary(1, etype)  # modified so counted
 
         actual_data = list(endpoint(storage, etype, 'get')([data.sha1_2]))
 
@@ -254,7 +293,8 @@
         }
 
         # when
-        endpoint(storage, etype, 'add')([data_rev1])
+        summary = endpoint(storage, etype, 'add')([data_rev1])
+        assert summary == expected_summary(1, etype)
 
         with pytest.raises(DuplicateId):
             endpoint(storage, etype, 'add')(
@@ -285,7 +325,8 @@
         }
 
         # when
-        endpoint(storage, etype, 'add')([data1])
+        summary = endpoint(storage, etype, 'add')([data1])
+        assert summary == expected_summary(1, etype)
 
         # then
         actual_data = list(endpoint(storage, etype, 'get')(query))
@@ -843,13 +884,16 @@
         }
 
         # when
-        endpoint(storage, etype, 'add')([data1])
-        endpoint(storage, etype, 'delete')([
+        summary = endpoint(storage, etype, 'add')([data1])
+        assert summary == expected_summary(1, etype)
+
+        summary2 = endpoint(storage, etype, 'delete')([
             {
                 'id': data.sha1_2,
                 'indexer_configuration_id': tool['id'],
             }
         ])
+        assert summary2 == expected_summary(1, etype, 'del')
 
         # then
         actual_data = list(endpoint(storage, etype, 'get')(query))
diff --git a/swh/indexer/tests/test_fossology_license.py b/swh/indexer/tests/test_fossology_license.py
--- a/swh/indexer/tests/test_fossology_license.py
+++ b/swh/indexer/tests/test_fossology_license.py
@@ -36,7 +36,7 @@
                  ['GPL', 'AGPL'])]:
             mock_subprocess.check_output.return_value = intermediary_result
 
-            actual_result = compute_license(path, log=None)
+            actual_result = compute_license(path)
 
             self.assertEqual(actual_result, {
                 'licenses': output,
@@ -44,7 +44,7 @@
             })
 
 
-def mock_compute_license(path, log=None):
+def mock_compute_license(path):
     """path is the content identifier
 
     """
diff --git a/swh/indexer/tests/utils.py b/swh/indexer/tests/utils.py
--- a/swh/indexer/tests/utils.py
+++ b/swh/indexer/tests/utils.py
@@ -746,12 +746,12 @@
         start, end = map(hashutil.hash_to_bytes, (_start, _end))
 
         # given
-        actual_results = self.indexer.run(  # checks the bytes input this time
+        actual_results = self.indexer.run(
             start, end, skip_existing=False)
         # no already indexed data so same result as prior test
 
         # then
-        self.assertTrue(actual_results)
+        self.assertEquals(actual_results, {'status': 'uneventful'})
 
     def test_generate_content_get_no_result(self):
         """No result indexed returns False"""
@@ -759,8 +759,7 @@
                         '0000000000000000000000000000000000000001']
         start, end = map(hashutil.hash_to_bytes, (_start, _end))
         # given
-        actual_results = self.indexer.run(
-            start, end, incremental=False)
+        actual_results = self.indexer.run(start, end, incremental=False)
 
         # then
-        self.assertFalse(actual_results)
+        self.assertEquals(actual_results, {'status': 'uneventful'})