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Re: very poor performance of opening tables
Posted by: J G
Date: September 23, 2005 10:51AM

> I really hope this is a typo and you meant *with*
> indexes...

Yes, I reedited post. There are with indexes.

> file descriptor. If you have tens of thousands of
> tables, even if you up the table_cache, the OS may
> not be (and clearly isn't) able to deal with that
> many file descriptors at once. The number of file
> descriptors and th speed at which file descriptors
> are handled is very OS-dependent. I honestly
> don't know how many file descriptors FreeBSD 5.4
> with linux_threads is able to handle, but millions
> is certainly not an option.

I tuned max file descriptors up to 200 000, but it's too much for my server. Now I have table_cache at 8192 so mysql uses about 16 000 descriptors and it's not bad set. Setting higher value don't give me noticable performance hit. I'm sure this problem is not releated to maximum number of allowed file decriptors. OS or MySQL seems to have problem with opening a lots of tables in the same time. I don't have ideas what to do with it.
It will be a good thing to check if my freebsd will also has poblem with opening a lot of raw files in the same time, but I can't have idea how to check it to have reliable results.

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J G
September 23, 2005 06:11AM
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September 23, 2005 08:59AM
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J G
September 23, 2005 10:40AM
Re: very poor performance of opening tables
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J G
September 23, 2005 10:51AM
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J G
September 25, 2005 09:45AM
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September 25, 2005 10:34AM
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J G
September 25, 2005 11:16AM
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September 26, 2005 06:02AM
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J G
October 16, 2005 11:25AM


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