So, this is essentially what's suggested in the patch (with new
variables to control behavior and tests to check all these):
...
+ /* New logaritmic number of pages that are estimated. We
+ first pick minimun from srv_stats_sample_pages and number of
+ pages on index. Then we pick maximum from previous number of
+ pages and log2(number of index pages) * srv_stats_sample_pages.
*/
if (index->stat_index_size > 0) {
- n_sample_pages = index->stat_index_size;
+ n_sample_pages = ut_max(ut_min(srv_stats_sample_pages,
index->stat_index_size),
+
log2(index->stat_index_size)*srv_stats_sample_pages);
} else {
n_sample_pages = 1;
...
This may surely work better than default setting or even any one picked
by DBA based on some reasoning. So, I think we should consider this
feature seriously (for 5.5 and for tables that do not use persistent
statistics in 5.6).
** Also affects: percona-server/5.6
Importance: Undecided
Status: New
** Also affects: percona-server/5.5
Importance: Undecided
Status: New
** Changed in: percona-server/5.6
Status: New => Confirmed
** Changed in: percona-server/5.5
Status: New => Confirmed
** Bug watch added: MySQL Bug System #74935
http://bugs.mysql.com/bug.php?id=74935
** Also affects: mysql-server via
http://bugs.mysql.com/bug.php?id=74935
Importance: Unknown
Status: Unknown
** Tags added: contribution upstream
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https://bugs.launchpad.net/bugs/1394483
Title:
innodb index stats inadequate using constant innodb_stats_sample_pages
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