Re: Strange issues with 9.2 pg_basebackup & replication

More issues: the pg_basebackup -x stream on the cascading replica won't
complete until the xlog rotates on the master.  (again, this is
Tuesday's snapshot).

Servers:
.226 == master-master, the writeable master
.227 == master-replica, a direct replica of master-master
.228 == replica-replica, a cascading replica of master-replica

1. recreated master-master, loaded it with some dummy databases.

2. created master-replica

3. took pg_basebackup -x stream of master-master on master-replica

4. edited recovery.conf and started master-replica.  started normally.

5. created a table on master-master.  change replicated to master-replica.

6. created replica-replica.  started a pg_basebackup -x stream from
master-replica

7. pg_basebackup hung forever.  output of -v:

xlog start point: 0/A000020
pg_basebackup: starting background WAL receiver

xlog end point: 0/A01C188
pg_basebackup: waiting for background process to finish streaming...

8. tried creating a table on master-master to create a write.  this had
no effect (although the table did replicate to master-replica).

Here's pg_stat_replication on master-master while the basebackup is hung:
1385 |    16393 | replicator | walreceiver      | ###.###.61.227 |           |       45396 | 2012-
05-13 19:05:11.972471+00 | streaming | 0/A024F50     | 0/A024F50      |
0/A024F50      | 0/A024F50
|             0 | async

Here's pg_stat_replication on master-replica while basebackup is hung:
1243 |    16393 | replicator | pg_basebackup    | ###.###.61.228 |           |       49218 | 2012-
05-13 19:06:07.606378+00 | startup   | 0/0           |                |              |
|             0 | async1244 |    16393 | replicator | pg_basebackup    | ###.###.61.228 |           |       49219 |
2012-
05-13 19:06:07.611996+00 | streaming | 0/A024F50     |                |              |
|             0 | async


9. Ran pg_xlog_switch() on the master.

10. basebackup completed on replica-replica.

11. edited recovery.conf on replica-replica and started it.  works fine.

12. created a new table on master-master, changed replicated to
replica-replica.


-- 
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com