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From:Krishna Chandra Prajapati Date:April 30 2008 5:38am
Subject:Re: mysql variables
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Hi Dan,

I am worried about Key_blocks_unused. when Key_blocks_unused reach to 0.
There will be no free blocks then how insert query will work.

Krishna Chandra Prajapati

On Wed, Apr 30, 2008 at 10:42 AM, Dan Nelson <dnelson@stripped>

> In the last episode (Apr 30), Krishna Chandra Prajapati said:
> > Key_blocks_unused                  952405
> > Key_blocks_used                    395539
> >
> > Key_blocks_used  is increasing day by day and Key_blocks_unused is
> > decreasing day by day. Ater a month Key_blocks_unused will reach to
> > 0. Does it mean that i need to increase the key_buffer_size. Already
> > key_buffer_size=1G.
> >
> > While going through forums and lists , i found that when
> > key_blocks_unused is less. then select query will become slow. So
> > whats the right solution.
> In a perfect world, you would set key_buffer_size to the total size of
> all your .MYI files.  Depending on the size of your tables, that may
> simply not be possible.  Luckily, it's usually not necessary, either.
> What is more important is the hit rate.  Run "SHOW STATUS LIKE 'key%'",
> and compare Key_read_requests (how many times mysql asked for a key)
> against Key_reads (how many times mysql actually had to go to disk to
> fetch a key).  1-(Key_reads/Key_read_requests) is your read hit rate.
> If it's 0.99 or greater, that means that 99% of your key reads are
> already coming from the key buffer, and adding more key buffers is
> unlikely to give you a measurable performance increase.
> Don't worry too much about your write hit rate (
> 1-(Key_writes/Key_write_requests) ); it's always going to be lower
> because mysql tries to keep the on-disk copy of the index up to date.
> --
>        Dan Nelson
>        dnelson@stripped
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Krishna Chandra Prajapati

mysql variablesKrishna Chandra Prajapati30 Apr
  • Re: mysql variablesDan Nelson30 Apr
    • Re: mysql variablesKrishna Chandra Prajapati30 Apr
      • Re: mysql variablesSebastian Mendel30 Apr
      • Re: mysql variablesDan Nelson30 Apr