local_cached_downto status variable underflow

[Raghavendra D Prabhu]

wsrep_local_cached_downto added in https://bugs.launchpad.net/galera/+bug/1252460 underflows when the node on which it is queried has no writesets in gcache. This is because seqno_min returns -1 in that case.

MySQL [(none)]> show global status like '%local_cached_downto%';
+---------------------------+----------------------+
| Variable_name | Value |
+---------------------------+----------------------+
| wsrep_local_cached_downto | 18446744073709551615 |
+---------------------------+----------------------+
1 row in set (0.00 sec)

It should show 0 in this case. (or -1 if possible)

[Alex Yurchenko (ayurchen)]

More precisely, it should show actual lowest seqno that may be present in its gcache. So for galera <= 3.x it is configuration seqno + 1, for galera 4.x - there always will be something in gcache.

[Alexey Kopytov (akopytov)]

Fixed as https://github.com/percona/galera/issues/12

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PXC-337

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PXC-315