Merge ~cjwatson/launchpad:merge-db-stable into launchpad:master

[Colin Watson]

Merge db-stable 66921f2f68 (Add ArchiveDependency.snap_base and SnapBuild.snap_base)

[Colin Watson (cjwatson)]

Deployed to the production database today.

review: Approve

diff --git a/database/schema/patch-2210-30-0.sql b/database/schema/patch-2210-30-0.sql
new file mode 100644
index 0000000..c7190e9
--- /dev/null
+++ b/database/schema/patch-2210-30-0.sql
@@ -0,0 +1,21 @@
+-- Copyright 2021 Canonical Ltd.  This software is licensed under the
+-- GNU Affero General Public License version 3 (see the file LICENSE).
+
+SET client_min_messages=ERROR;
+
+ALTER TABLE ArchiveDependency
+    ADD COLUMN snap_base integer REFERENCES snapbase,
+    ALTER COLUMN archive DROP NOT NULL,
+    ADD CONSTRAINT one_parent CHECK (null_count(ARRAY[archive, snap_base]) = 1);
+
+CREATE INDEX archivedependency__snap_base__idx
+    ON ArchiveDependency (snap_base);
+
+COMMENT ON TABLE ArchiveDependency IS 'This table maps a given parent (archive or snap base) to all other archives it should depend on.';
+COMMENT ON COLUMN ArchiveDependency.snap_base IS 'The snap base that has this dependency.';
+
+ALTER TABLE SnapBuild ADD COLUMN snap_base integer REFERENCES snapbase;
+
+COMMENT ON COLUMN SnapBuild.snap_base IS 'The snap base to use for this build.';
+
+INSERT INTO LaunchpadDatabaseRevision VALUES (2210, 30, 0);