Upgrading Postgres

Upgrade-Postgres-%28Major-Versions%29.md

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+Upgrading postgres is done via a backup/restore operation.
+
+The easiest way to upgrade is (example, upgrade from Postgresl 15 to Postgres 17):
+
+* Stop all services
+* Move existing database into a directory, eg: `mv postgres postgres.15`
+* Update the `docker-compose` file
+
+```yaml
+  postgres_old:
+    image: postgres:15-alpine
+    deploy:
+      resources:
+        limits:
+          memory: 512M
+    environment:
+      POSTGRES_DB: ${DB_DATABASE:-clrghouz}
+      POSTGRES_USER: ${DB_USERNAME:-clrghouz}
+      POSTGRES_PASSWORD: ${DB_PASSWORD}
+    shm_size: 1g
+    volumes:
+    - ${VOL_PREFIX:-/srv/docker/clrghouz}/postgres.15:/var/lib/postgresql/data
+
+ postgres:
+    image: postgres:17-alpine
+    deploy:
+      resources:
+        limits:
+          memory: 512M
+    environment:
+      POSTGRES_DB: ${DB_DATABASE:-clrghouz}
+      POSTGRES_USER: ${DB_USERNAME:-clrghouz}
+      POSTGRES_PASSWORD: ${DB_PASSWORD}
+    shm_size: 1g
+    volumes:
+    - ${VOL_PREFIX:-/srv/docker/clrghouz}/postgres.17:/var/lib/postgresql/data
+```
+
+Start the environment, and stop all the containers except the two database environments (postgres_15,postgres).
+
+Export the database out of the old environment and into the new, where:
+
+* `2b5fae8b7394` is the container ID of the old database (postgres.15)
+* `08cb53dfa922` is the container ID of the new database (postgres)
+
+`docker exec -t 2b5fae8b7394 pg_dumpall -U ${DB_DATABASE:-clrghouz} | docker exec -i 08cb53dfa922 psql -U ${DB_DATABASE:-clrghouz}`
+
+The old DB can now be stopped, and the old DB configuration in the `docker-compose` file can be commented out.
+
+In case something goes pear shaped, the old database is still there if you need to revert to it (it wasnt affected by this operation).