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From:Rick James Date:August 28 2012 4:40pm
Subject:RE: qcache settings and block meaning
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> | Qcache_hits                       | 56418967     |
> | Qcache_inserts                    | 48601636     |
That's a low hit rate.  Perhaps you should simply turn off the Query cache?

> | Qcache_free_memory                | 46945512     |
That's a big fraction of the total.  Either the QC is unnecessarily big, or it was
recently purged.

> | Qcache_lowmem_prunes              | 21948806     |
What is Uptime?  This may be a lot of prunes per second.

Purging stuff out of 128MB _may_ slow your system down more than the benefit you are
getting.
I recommend turning off the QC for systems with constant write activity.
Otherwise, 50M is a reasonable max.

> -----Original Message-----
> From: raphinou@stripped [mailto:raphinou@stripped] On Behalf Of
> Raphael Bauduin
> Sent: Tuesday, August 28, 2012 7:12 AM
> To: mysql@stripped
> Subject: qcache settings and block meaning
> 
> Hi,
> 
> I have a mysql server running with the query cache size being 128M
> (134217728 bytes).
> 
> Here are the qcache variables values:
> 
> | Qcache_free_blocks                | 13758        |
> | Qcache_free_memory                | 46945512     |
> | Qcache_hits                       | 56418967     |
> | Qcache_inserts                    | 48601636     |
> | Qcache_lowmem_prunes              | 21948806     |
> | Qcache_not_cached                 | 39066097     |
> | Qcache_queries_in_cache           | 44858        |
> | Qcache_total_blocks               | 104668
> 
> And the query_cache_min_res_unit is 4096 .
> 
> I'm not sure what the meaning of a block is. For the query cache size
> and the number of total blocks, I have a block size of
> 134217728/104668 = 1282.3186 , which is a strange number for a block
> size. Am I wrong somewhere?
> 
> Thanks
> 
> Raph
> 
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Thread
qcache settings and block meaningRaphael Bauduin28 Aug
  • Re: qcache settings and block meaningJohan De Meersman28 Aug
  • RE: qcache settings and block meaningRick James28 Aug
    • Re: qcache settings and block meaningRaphael Bauduin29 Aug
      • RE: qcache settings and block meaningRick James29 Aug
        • Re: qcache settings and block meaningRaphael Bauduin30 Aug