pt-query-digest --processlist reports duplicate queries for replication thread

[Nickolay Ihalainen]

pt-query-digest --processlist can't merge correctly show full processlist outputs for slave thread. As a result wrong queries could be listed in a report.

percona toolkit 2.1.8 and 2.1.5 versions are affected.

/usr/local/sbin/pt-query-digest --interval 0.2 --filter '$event->{Query_time} > 1' --processlist h=SERVER,u=USER -p PASSWORD --print --no-report --run-time 3600 > logs/SERVER-`date +%Y%m%d-%H`

Replication thread can't execute two queries in parallel at the same time:

 Processlist:2417 25797 Polling PROCESSLIST
# Processlist:2428 25797 Rows: 3 in 0.000298976898193359 seconds
# Processlist:2488 25797 New cxn 166
# Processlist:2442 25797 Checking existing cxn 167
# Processlist:2458 25797 Query restarted; new query 1363226464.1831 0.000298976898193359 1363226463 1
# Processlist:2565 25797 Query is still in Repair by sorting state
# Processlist:2547 25797 Properties of event: $VAR1 = {
# Lock_time => 0,
# Query_time => 21,
# arg => 'OPTIMIZE TABLE t',
# bytes => 46,
# db => 't',
# host => '',
# id => 167,
# ts => '2013-03-14T02:01:24',
# user => 'system user'
# };

# Processlist:2417 25797 Polling PROCESSLIST
# Processlist:2428 25797 Rows: 3 in 0.000288009643554688 seconds
# Processlist:2488 25797 New cxn 166
# Processlist:2442 25797 Checking existing cxn 167
# Processlist:2449 25797 Info is different; new query
# Processlist:2569 25797 Query changed from state Sorting index to undef
# Processlist:2547 25797 Properties of event: $VAR1 = {
# Lock_time => 0,
# Query_time => 21,
# arg => 'OPTIMIZE TABLE t',
# bytes => 46,
# db => 't',
# host => '',
# id => 167,
# ts => '2013-03-14T02:01:25',
# user => 'system user'
# };

[Daniel Nichter (daniel-nichter)]

I think there's another bug about this, basically that pt-query-digest --processlist thinks a new event has happened when the same process's state has changed, so really it's the same event.

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PT-605