Brian "Krow" Aker (krow) wrote,
Brian "Krow" Aker
krow

Open Tables, why should I pay attention?

In discussion the other day a co-worker was looking at a benchmark
that I had created for a problem I was studying on threads with write
performance.

He asked "What is open tables set at?"

I responded that I had it set to a thousand, which is normal the
value I keep on the machine I do development on. I normally look at
300 connections as an average load, but every so often I crank it up
to around a 1000 depending on the test (which is a pretty high
simulation, and not common among the average large websites).

It crossed my mind at this point that I had no idea how the database
behaved with default value in MySQL, which is 64, when you were
running with this many threads. Anyone who has a large number of
threads touching tables knows to crank up the table cache.

As the graph points out, depending on which engine you are dealing
with, it can make quite a bit of difference :)

The my.cnf setting for this looks like this:

set-variable = table_open_cache=1000
Picture 6.jpg

Tags: mysql
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