Unnecessary calls to innobase_get_trx() if slow log is enabled, but InnoDB stats are not

[Alexey Kopytov]

We have the following code in buf_page_get_zip(), buf_page_get_gen(), buf_page_opimistic_get() and buf_page_get_known_nowait():

 if (innobase_get_slow_log()) {
  trx = innobase_get_trx();
 }

The problem is that innobase_get_trx() is expensive due to current_thd and if the slow log is enabled, but InnoDB stats are not, it will still be called for no reasons, as trx->take_stats will be FALSE and no stats will actually be collected.

[Laurynas Biveinis (laurynas-biveinis)]

If I may piggyback on this bug report, as the issue is too minor for its own bug report and can be fixed at the same time. The innobase_get_trx() prototype should be removed from buf0buf.c. Instead, it should be declared in ha_prototypes.h.

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-1315