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Bug 12356373 - PERFORMANCE REGRESSION FROM 5.1 TO 5.5 : GROUP BY:

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The title of the bug is a little confusing. The actual fix is to
reintroduce random readahead inside InnoDB with a dynamic, global
switch innodb_random_read_ahead [default = off].

Approved by: Sunny Bains
rb://696
This commit is contained in:
Inaam Rana
2011-07-19 10:37:37 -04:00
parent 0f543e8e9d
commit aa3d29681e
8 changed files with 232 additions and 7 deletions
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4
storage/innodb_plugin/srv/srv0srv.c
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@@ -203,6 +203,8 @@ UNIV_INTERN ulint srv_n_file_io_threads = ULINT_MAX;
UNIV_INTERN ulint srv_n_read_io_threads = ULINT_MAX;
UNIV_INTERN ulint srv_n_write_io_threads = ULINT_MAX;
/* Switch to enable random read ahead. */
UNIV_INTERN my_bool srv_random_read_ahead = FALSE;
/* User settable value of the number of pages that must be present
in the buffer cache and accessed sequentially for InnoDB to trigger a
readahead request. */
@@ -1906,6 +1908,8 @@ srv_export_innodb_status(void)
export_vars.innodb_buffer_pool_wait_free = srv_buf_pool_wait_free;
export_vars.innodb_buffer_pool_pages_flushed = srv_buf_pool_flushed;
export_vars.innodb_buffer_pool_reads = srv_buf_pool_reads;
export_vars.innodb_buffer_pool_read_ahead_rnd
= buf_pool->stat.n_ra_pages_read_rnd;
export_vars.innodb_buffer_pool_read_ahead
= buf_pool->stat.n_ra_pages_read;
export_vars.innodb_buffer_pool_read_ahead_evicted