Merge lp:~cjwatson/launchpad/postgresql-10-more-replication into lp:launchpad

[Colin Watson]

Handle renaming of pg_stat_replication.replay_location to pg_stat_replication.replay_lsn in PostgreSQL 10.

Spotted in staging logs:

Traceback (most recent call last):
  File "./full-update.py", line 232, in <module>
    sys.exit(main())
  File "./full-update.py", line 116, in main
    if not NoConnectionCheckPreflight(log, controller).check_all():
  File "/srv/staging.launchpad.net/staging/launchpad/database/schema/preflight.py", line 313, in check_all
    if not self.replication_paused and not self.check_can_sync():
  File "/srv/staging.launchpad.net/staging/launchpad/database/schema/preflight.py", line 281, in check_can_sync
    streaming_success = streaming_sync(self.lpmain_master_node.con, 30)
  File "/srv/staging.launchpad.net/staging/launchpad/database/schema/dbcontroller.py", line 52, in streaming_sync
    """, (wal_point,))
psycopg2.ProgrammingError: column "replay_location" does not exist
LINE 3: WHERE replay_location < E'4B61/FF003210' LIMIT 1
                          ^

[William Grant (wgrant)]

review: Approve (code)

=== modified file 'database/schema/dbcontroller.py'
--- database/schema/dbcontroller.py	2019-03-05 13:30:42 +0000
+++ database/schema/dbcontroller.py	2019-03-25 21:18:51 +0000
@@ -46,10 +46,16 @@
     wal_point = cur.fetchone()[0]
     start_time = time.time()
     while timeout is None or time.time() < start_time + timeout:
-        cur.execute("""
-            SELECT FALSE FROM pg_stat_replication
-            WHERE replay_location < %s LIMIT 1
-            """, (wal_point,))
+        if con.server_version >= 100000:
+            cur.execute("""
+                SELECT FALSE FROM pg_stat_replication
+                WHERE replay_lsn < %s LIMIT 1
+                """, (wal_point,))
+        else:
+            cur.execute("""
+                SELECT FALSE FROM pg_stat_replication
+                WHERE replay_location < %s LIMIT 1
+                """, (wal_point,))
         if cur.fetchone() is None:
             # All slaves, possibly 0, are in sync.
             return True