chore: simplify migration script postgres version_4 (#2674)

migrations/message_store_postgres/content_script_version_4.nim

@@ -1,72 +1,9 @@
 const ContentScriptVersion_4* =
   """
-ALTER TABLE IF EXISTS messages_backup RENAME TO messages;
-ALTER TABLE messages RENAME TO messages_backup;
-
-CREATE TABLE IF NOT EXISTS messages (
-   pubsubTopic VARCHAR NOT NULL,
-   contentTopic VARCHAR NOT NULL,
-   payload VARCHAR,
-   version INTEGER NOT NULL,
-   timestamp BIGINT NOT NULL,
-   id VARCHAR NOT NULL,
-   messageHash VARCHAR NOT NULL,
-   storedAt BIGINT NOT NULL,
-   meta VARCHAR,
-   CONSTRAINT messageIndex PRIMARY KEY (messageHash, storedAt)
-  ) PARTITION BY RANGE (storedAt);
-
-DO $$
-DECLARE
-     min_storedAt numeric;
-     max_storedAt numeric;
-     min_storedAtSeconds integer = 0;
-     max_storedAtSeconds integer = 0;
-     partition_name TEXT;
-     create_partition_stmt TEXT;
-BEGIN
-    SELECT MIN(storedAt) into min_storedAt
-    FROM messages_backup;
-
-    SELECT MAX(storedAt) into max_storedAt
-    FROM messages_backup;
-
-    min_storedAtSeconds := min_storedAt / 1000000000;
-    max_storedAtSeconds := max_storedAt / 1000000000;
-
-    partition_name := 'messages_' || min_storedAtSeconds || '_' || max_storedAtSeconds;
-    create_partition_stmt := 'CREATE TABLE ' || partition_name ||
-                            ' PARTITION OF messages FOR VALUES FROM (' ||
-                            min_storedAt || ') TO (' || (max_storedAt + 1) || ')';
-    IF min_storedAtSeconds > 0 AND max_storedAtSeconds > 0 THEN
-    	EXECUTE create_partition_stmt USING partition_name, min_storedAt, max_storedAt;
-    END IF;
-END $$;
-
-INSERT INTO messages (
-                        pubsubTopic,
-                        contentTopic,
-                        payload,
-                        version,
-                        timestamp,
-                        id,
-                        messageHash,
-                        storedAt
-                     )
-                SELECT pubsubTopic,
-                       contentTopic,
-                       payload,
-                       version,
-                       timestamp,
-                       id,
-                       messageHash,
-                       storedAt
-                   FROM messages_backup;
+ALTER TABLE messages ADD meta VARCHAR default null;
 
 CREATE INDEX IF NOT EXISTS i_query ON messages (contentTopic, pubsubTopic, storedAt, id);
 
-DROP TABLE messages_backup;
-
 UPDATE version SET version = 4 WHERE version = 3;
 
 """