Comments on: The MySQL Query Cache: How it works, plus workload impacts https://www.percona.com/blog/the-mysql-query-cache-how-it-works-and-workload-impacts-both-good-and-bad/ Fri, 29 Dec 2023 00:51:31 +0000 hourly 1 https://wordpress.org/?v=6.5.2 By: MarcH https://www.percona.com/blog/the-mysql-query-cache-how-it-works-and-workload-impacts-both-good-and-bad/#comment-10968896 Sun, 14 Jan 2018 16:24:14 +0000 https://www.percona.com/blog/?p=27490#comment-10968896 Thanks folks, helped me much to improve & eval response time!

]]> By: Jitin Maherchandani https://www.percona.com/blog/the-mysql-query-cache-how-it-works-and-workload-impacts-both-good-and-bad/#comment-10965875 Wed, 10 Feb 2016 08:59:43 +0000 https://www.percona.com/blog/?p=27490#comment-10965875 I have a column in my table which keeps on changing very frequently .How should i implement caching on that particular table ,should i move this column to different table ? How should i avoid caching invalidation ?

]]> By: WPDIV https://www.percona.com/blog/the-mysql-query-cache-how-it-works-and-workload-impacts-both-good-and-bad/#comment-10965436 Fri, 16 Oct 2015 09:49:51 +0000 https://www.percona.com/blog/?p=27490#comment-10965436 How to optimize first Byte Connect time as you seen in the report?

]]> By: Anvesh Patel https://www.percona.com/blog/the-mysql-query-cache-how-it-works-and-workload-impacts-both-good-and-bad/#comment-10940762 Tue, 01 Sep 2015 17:39:41 +0000 https://www.percona.com/blog/?p=27490#comment-10940762 Nice Article !
I have also worked around this MySQL Query Cache and created my note in this blog:
please visit some of my view about MySQL Query Cache.
For basic theory :
http://www.dbrnd.com/2015/08/mysql-query-cache/
For basic configuration:
http://www.dbrnd.com/2015/08/mysql-query-cache-configuration/

]]> By: Daniël van Eeden https://www.percona.com/blog/the-mysql-query-cache-how-it-works-and-workload-impacts-both-good-and-bad/#comment-10355925 Wed, 07 Jan 2015 18:57:00 +0000 https://www.percona.com/blog/?p=27490#comment-10355925 I once wrote a blog about flushing the query cache w/o cron:
http://databaseblog.myname.nl/2011/06/regularly-flushing-mysql-query-cache.html

]]> By: Fadi El-Eter (itoctopus) https://www.percona.com/blog/the-mysql-query-cache-how-it-works-and-workload-impacts-both-good-and-bad/#comment-10349914 Mon, 05 Jan 2015 19:47:07 +0000 https://www.percona.com/blog/?p=27490#comment-10349914 Hi Arunjith,

Thanks a lot for explaining the free blocks concept. I will test it on a large website at night and see if I can run it through a cron every nigh (let me know if there are better ways).

]]> By: Arunjith Aravindan https://www.percona.com/blog/the-mysql-query-cache-how-it-works-and-workload-impacts-both-good-and-bad/#comment-10348339 Mon, 05 Jan 2015 06:07:32 +0000 https://www.percona.com/blog/?p=27490#comment-10348339 Hi Fadi,
The free blocks are the number of non-contiguous free memory blocks available in the query cache. Initially the query cache will be long and contiguous. Over time and with use, the long contiguous regions become fragmented into smaller and smaller contiguous areas.
To better utilize the memory you can defragment the query cache with help of FLUSH QUERY CACHE statement. Basically the FLUSH QUERY CACHE does not empty the query cache but it defragments the query cache and the value for the Qcache_free_blocks becomes ‘1’.

]]> By: Fadi El-Eter (itoctopus) https://www.percona.com/blog/the-mysql-query-cache-how-it-works-and-workload-impacts-both-good-and-bad/#comment-10344009 Sat, 03 Jan 2015 18:08:07 +0000 https://www.percona.com/blog/?p=27490#comment-10344009 Hi Arunjith,

Thanks for explaining the “qcache_lowmem_prunes” so clearly and concisely.

The post by Peter that a large query cache can cause serious performance issues is valid only when you have a query invalidating a large set of queries (we’re talking 10s of thousands of queries being invalidated). For most sites (especially non-transactional sites), this is not the case.

Also, would it be possible to give a brief explanation on what a free block is and how it works?

]]> By: Daniël van Eeden https://www.percona.com/blog/the-mysql-query-cache-how-it-works-and-workload-impacts-both-good-and-bad/#comment-10341066 Fri, 02 Jan 2015 17:05:16 +0000 https://www.percona.com/blog/?p=27490#comment-10341066 There is a nice query cache tuner made by Domas Mituzas:
http://dom.as/tech/query-cache-tuner/

]]>