fix(postgres): raise max_locks_per_transaction to 256

GitLab's migration on its dedicated postgres sidecar failed with "ERROR: out of shared memory" and the hint to raise max_locks_per_transaction. The default of 64 locks per transaction cannot cover a schema that locks thousands of tables and indexes in one transaction: a reproduction on postgres:18 failed at table 7453 with the default and held 20000 tables at 256.

The value sits next to the other postgres tuning constants in group_vars/all/17_resource.yml and reaches both the central svc-db-postgres command and the per-app sidecar. The sidecar's new command keeps the image entrypoint and only adds the flag. The shared lock table grows to about 256 x max_connections entries, roughly 30 MB at the 400-connection cap.

Ported from 7690d2ca6d on feature/store-i18n, which kept the constant in the resource lookup that main no longer has.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

group_vars/all/17_resource.yml

@@ -53,6 +53,7 @@ POSTGRES_WORK_MEM_MB: "{{ [ ( (POSTGRES_TOTAL_RAM_MB | int) // ( [ (POSTGRES_MAX
 POSTGRES_WORK_MEM: "{{ POSTGRES_WORK_MEM_MB ~ 'MB' }}"
 POSTGRES_MAINTENANCE_WORK_MEM_MB: "{{ [ (((POSTGRES_TOTAL_RAM_MB | int) * 5) // 100), 64 ] | max }}"
 POSTGRES_MAINTENANCE_WORK_MEM: "{{ POSTGRES_MAINTENANCE_WORK_MEM_MB ~ 'MB' }}"
+POSTGRES_MAX_LOCKS_PER_TRANSACTION: 256
 POSTGRES_DELAY: 2
 
 TIMEOUT_FACTOR: 1

roles/svc-db-postgres/templates/compose.yml.j2

@@ -16,6 +16,8 @@
       - "work_mem={{ POSTGRES_WORK_MEM }}"
       - "-c"
       - "maintenance_work_mem={{ POSTGRES_MAINTENANCE_WORK_MEM }}"
+      - "-c"
+      - "max_locks_per_transaction={{ POSTGRES_MAX_LOCKS_PER_TRANSACTION }}"
 
     {% include 'roles/sys-svc-container/templates/base.yml.j2' %}
     {{ lookup('container_healthcheck', service_name) | indent(4) }}

roles/sys-svc-rdbms/templates/services/postgres.yml.j2

@@ -15,6 +15,10 @@
 {% else %}
     {{ lookup('container_image', 'svc-db-postgres', 'postgres', image=lookup('database', application_id, 'image'), version=lookup('database', application_id, 'version')) }}
 {% endif %}
+    command:
+      - "postgres"
+      - "-c"
+      - "max_locks_per_transaction={{ POSTGRES_MAX_LOCKS_PER_TRANSACTION }}"
     env_file:
       - {{ lookup('database', application_id, 'env') }}
     {{ lookup('compose_restart') }}