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Re: PBXT issues
On May 5, 2010, at 7:02 PM, Michael Widenius wrote:
"Paul" == Paul McCullagh <paul.mccullagh@xxxxxxxxxxxxx> writes:
Paul> PBXT can help you out with this. Do the following:
Paul> (1) Load the telpbxt table with a few 1000 rows (or use
Paul> since telpbxt already has too many rows in it).
Paul> (2) In mysql client enter: CHECK TABLE telpbxt2; (note: do not
Paul> on a table with millions of rows. It will take very long to
Paul> (3) Check the MySQL error log, you should see something like the
Paul> output below.
Paul> CHECK TABLE: ./test/telpbxt
Paul> Record buffer size = 1024
Paul> Fixed length rec. len. = 1020
Paul> Handle data record size = 638
Paul> Min/max header size = 14/26
Paul> Min/avg/max record size = 19/624/1019
Paul> Avg row len set for tab = not specified
Paul> Rows fixed length = NO
Paul> Maximum fixed size = 16384
Paul> Paste the output in an e-mail, and I will show you what to use
Would it be hard for PBXT to as part of the CHECK TABLE add:
Optimial create AVG_ROW_LENGTH: ?
Currently CHECK TABLE prints:
Average comp. rec. len. = 200
This is the closest to your suggestion of an "Optimal create
AVG_ROW_LENGTH", there is at the moment.
But, this value is not necessarily optimal.
Exactly what is optimal depends on a few additional factors, like
whether you want to optimize for size or caching behavior.
What I can do is add more information to help in this decision making
process, and output a "Recommended AVG_ROW_LENGTH".
Then I can change OPTIMIZE TABLE to automatically set this value, if
no explicit AVG_ROW_LENGTH has been set yet.