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From:Grant Giddens Date:January 17 2006 2:11am
Subject:Re: key_buffer_size vs innodb_buffer_pool_size
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I don't know if I still fully understand.
  
  Say I have a database with a good mix of myisam and innodb type  tables.  If my server
has 1 gig of ram and I set  key_buffer_size=256M and innodb_buffer_pool_size=256M then
wouldn't  mysql be constrained to 512M of the ram and leave the remaining 512M to  the
other server services?
  
  For a large database, are they any guides that I can use to determine how much ram would
be optimal for my particular database?
  
  Thanks,
  Grant

Eric Bergen <eric.bergen@stripped> wrote:  The difference in recommendation size
comes from the different
techniques each storage engine uses for caching data. myisam
(key_buffer_size) only stores indexes where innodb_buffer_pool_size
stores both indexes and data. mysiam relies on the operating system to
cache data in ram which is why you don't want to use all available
memory for the key buffer.


On 1/14/06, Grant Giddens  wrote:
> Hi,
>
>  After reading through the example my.cnf files (large, huge, etc), I  started to
> wonder what the difference was between the isam  key_buffer_size and the innodb
> innodb_buffer_pool_size.
>
>  I realize that they are two different table types, but some of the docs  says to set
> the key_buffer_size to 25%-50% of the overall system  memory. The comments for the
> innodb_buffer_pool_size say that it can be  set to 50%-80% of the overall system memory.
>
> Maybe I  don't understand exactly the difference between the two because I don't 
> understand why they have different memory recommendations.
>
>  Is there any FAQs on the my.cnf file? How would you set these two  variables if you
> had an even mix of isam and innodb tables? Where can I  learn more about tweaking the
> my.cnf file? The mysql online  documentation is good, but I need a more basic description
> of these two  variables and all the other my.cnf settings.
>
>   Thanks,
>   Grant
>
>
>
> ---------------------------------
> Yahoo! Photos
>  Got holiday prints? See all the ways to get quality prints in your hands ASAP.
>


--
Eric Bergen
eric.bergen@stripped
http://www.ebergen.net

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Thread
key_buffer_size vs innodb_buffer_pool_sizeGrant Giddens15 Jan
  • Re: key_buffer_size vs innodb_buffer_pool_sizeEric Bergen15 Jan
    • Re: key_buffer_size vs innodb_buffer_pool_sizeGrant Giddens17 Jan
      • Re: key_buffer_size vs innodb_buffer_pool_sizesheeri kritzer24 Jan