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 +1,10 @@
+-- SWH DB schema upgrade
+-- from_version: 130
+-- to_version: 131
+-- description: Use sha1 instead of bigint as FK from origin_visit to snapshot (part 1: add new column)
+
+insert into dbversion(version, release, description)
+      values(131, now(), 'Work In Progress');
+
+alter table origin_visit add column snapshot sha1_git;
+comment on column origin_visit.snapshot is 'Origin snapshot at visit time';
diff --git a/swh/storage/db.py b/swh/storage/db.py
--- a/swh/storage/db.py
+++ b/swh/storage/db.py
@@ -311,6 +311,11 @@
             update_cols.append('metadata=%s')
             values.append(jsonize(updates.pop('metadata')))
         if 'snapshot' in updates:
+            # New 'snapshot' column
+            update_cols.append('snapshot=%s')
+            values.append(updates['snapshot'])
+
+            # Old 'snapshot_id' column
             update_cols.append('snapshot_id=snapshot.object_id')
             from_ = 'FROM snapshot'
             where.append('snapshot.id=%s')
diff --git a/swh/storage/sql/30-swh-schema.sql b/swh/storage/sql/30-swh-schema.sql
--- a/swh/storage/sql/30-swh-schema.sql
+++ b/swh/storage/sql/30-swh-schema.sql
@@ -211,7 +211,8 @@
   date         timestamptz not null,
   status       origin_visit_status not null,
   metadata     jsonb,
-  snapshot_id  bigint
+  snapshot_id  bigint,
+  snapshot     sha1_git
 );
 
 comment on column origin_visit.origin is 'Visited origin';
@@ -220,6 +221,7 @@
 comment on column origin_visit.status is 'Visit result';
 comment on column origin_visit.metadata is 'Origin metadata at visit time';
 comment on column origin_visit.snapshot_id is 'Origin snapshot at visit time';
+comment on column origin_visit.snapshot is 'Origin snapshot at visit time';
 
 
 -- A snapshot represents the entire state of a software origin as crawled by