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From:Michael Widenius Date:April 2 1999 11:08am
Subject:powers of two in my.cnf ?
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>>>>> "matthew" == matthew mcglynn <mcglynn@stripped> writes:

matthew> This is probably a really dumb question...

matthew> Every example of buffer settings I've seen 
matthew> has used powers of two. For example, from the
matthew> sample configuration file:
matthew> set-variable    = key_buffer=16M
matthew> set-variable    = max_allowed_packet=1M
matthew> set-variable    = thread_stack=128K
matthew> set-variable    = max_allowed_packet=16M
matthew> set-variable    = keybuffer=16M

matthew> Similarly, the default table_cache is 64, and when
matthew> people ask on this list about running out of file
matthew> descriptors, the response is usually "set table_cache
matthew> to 32".

matthew> My dumb question is: do these have to all be powers of two ?!

matthew> If for my application, a table_cache of 128 is insufficient,
matthew> can I bump it to 150 or do I need to go all the way to 256 ?

Hi!

I just prefer to use powers as two as this gives you the best memory
utilization with many memory allocation packages!

You don't however have to use powers of two;  For the table cache 150
should be fine!

Regards,
Monty
Thread
powers of two in my.cnf ?matthew mcglynn2 Apr
  • powers of two in my.cnf ?Michael Widenius2 Apr
  • Re: powers of two in my.cnf ?Sasha Pachev2 Apr
Re: powers of two in my.cnf ?jkraai2 Apr