The branch, master has been updated
via 9b2570b0cfa73860fd150d741535991308b5b199 (commit)
via 9be1bad63ca9eb61ed8dcc249b45079f018f73ad (commit)
from 80daf344942c5b60b0c244771b7c18c309edf06d (commit)
- Log -----------------------------------------------------------------
commit 9b2570b0cfa73860fd150d741535991308b5b199
Author: Piotr Przybylski <[email protected]>
Date: Sat Aug 20 00:59:11 2011 +0200
Advisor: mark that 'Rate of reading fixed position' may be wrong, requires
further investigation
commit 9be1bad63ca9eb61ed8dcc249b45079f018f73ad
Author: Piotr Przybylski <[email protected]>
Date: Sat Aug 20 00:56:06 2011 +0200
Advisor: link to MySQL 5.5 documentation, it's better and more complete
-----------------------------------------------------------------------
Summary of changes:
libraries/advisory_rules.txt | 9 +++++----
1 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/libraries/advisory_rules.txt b/libraries/advisory_rules.txt
index 97f4454..c3445e0 100644
--- a/libraries/advisory_rules.txt
+++ b/libraries/advisory_rules.txt
@@ -131,7 +131,7 @@ rule 'Query cache usage' [!fired('Query cache disabled')]
Questions / Uptime
value > 100
Suboptimal caching method.
- You are using the MySQL Query cache with a fairly high traffic
database. It might be worth considering to use <a
href="http://dev.mysql.com/doc/refman/5.1/en/ha-memcached.html";>memcached</a>
instead of the MySQL Query cache, especially if you have multiple slaves.
+ You are using the MySQL Query cache with a fairly high traffic
database. It might be worth considering to use <a
href="http://dev.mysql.com/doc/refman/5.5/en/ha-memcached.html";>memcached</a>
instead of the MySQL Query cache, especially if you have multiple slaves.
The query cache is enabled and the server receives %d queries per
second. This rule fires if there is more than 100 queries per second. |
round(value,1)
rule 'Query cache efficiency (%)' [Com_select + Qcache_hits > 0 &&
!fired('Query cache disabled')]
@@ -214,6 +214,7 @@ rule 'Rate of reading first index entry'
This usually indicates frequent full index scans. Full index scans are
faster than table scans but require lots of CPU cycles in big tables, if those
tables that have or had high volumes of UPDATEs and DELETEs, running 'OPTIMIZE
TABLE' might reduce the amount of and/or speed up full index scans. Other than
that full index scans can only be reduced by rewriting queries.
Index scans average: %s, this value should be less than 1 per hour |
PMA_bytime(value,2)
+# This rule may be applicable to MyISAM-only workloads, but completely wrong
for InnoDB -
http://www.mysqlperformanceblog.com/2010/06/15/what-does-handler_read_rnd-mean/
rule 'Rate of reading fixed position'
Handler_read_rnd / Uptime
value * 60 * 60 > 1
@@ -247,19 +248,19 @@ rule 'Temp disk rate'
Created_tmp_disk_tables / Uptime
value * 60 * 60 > 1
Many temporary tables are being written to disk instead of being kept
in memory.
- Increasing {max_heap_table_size} and {tmp_table_size} might help.
However some temporary tables are always being written to disk, independent of
the value of these variables. To eliminate these you will have to rewrite your
queries to avoid those conditions (Within a temprorary table: Presence of a
BLOB or TEXT column or presence of a column bigger than 512 bytes) as mentioned
in in the <a
href="http://dev.mysql.com/doc/refman/5.0/en/internal-temporary-tables.html";>MySQL
Documentation</a>
+ Increasing {max_heap_table_size} and {tmp_table_size} might help.
However some temporary tables are always being written to disk, independent of
the value of these variables. To eliminate these you will have to rewrite your
queries to avoid those conditions (Within a temprorary table: Presence of a
BLOB or TEXT column or presence of a column bigger than 512 bytes) as mentioned
in in the <a
href="http://dev.mysql.com/doc/refman/5.5/en/internal-temporary-tables.html";>MySQL
Documentation</a>
Rate of temporay tables being written to disk: %s, this value should be
less than 1 per hour | PMA_bytime(value,2)
# I couldn't find any source on the internet that suggests a direct relation
between high counts of temporary tables and any of these variables.
# Several independent Blog entries suggest
(http://ronaldbradford.com/blog/more-on-understanding-sort_buffer_size-2010-05-10/
and http://www.xaprb.com/blog/2010/05/09/how-to-tune-mysqls-sort_buffer_size/)
# that sort_buffer_size should be left as it is. And increasing
read_buffer_size is only suggested when there are a lot of
-# table scans
(http://dev.mysql.com/doc/refman/5.1/en/server-system-variables.html#sysvar_read_buffer_size
and other sources) though
+# table scans
(http://dev.mysql.com/doc/refman/5.5/en/server-system-variables.html#sysvar_read_buffer_size
and other sources) though
# setting it too high is bad too
(http://www.mysqlperformanceblog.com/2007/09/17/mysql-what-read_buffer_size-value-is-optimal/).
#rule 'Temp table rate'
# Created_tmp_tables / Uptime
# value * 60 * 60 > 1
# Many intermediate temporary tables are being created.
-# This may be caused by queries under certain conditions as mentioned in
the <a
href="http://dev.mysql.com/doc/refman/5.0/en/internal-temporary-tables.html";>MySQL
Documentation</a>. Consider increasing {sort_buffer_size} (sorting),
{read_rnd_buffer_size} (random read buffer, ie, post-sort), {read_buffer_size}
(sequential scan).
+# This may be caused by queries under certain conditions as mentioned in
the <a
href="http://dev.mysql.com/doc/refman/5.5/en/internal-temporary-tables.html";>MySQL
Documentation</a>. Consider increasing {sort_buffer_size} (sorting),
{read_rnd_buffer_size} (random read buffer, ie, post-sort), {read_buffer_size}
(sequential scan).
#
# MyISAM index cache
hooks/post-receive
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