-----Ursprüngliche Nachricht-----
Von: Heikki Tuuri <[EMAIL PROTECTED]>
An: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Datum: 17 March, 2001 17:35
Betreff: Re: Innobase in MySQL
>Andy,
>
>thank you for your benchmark :). I was also going to measure these,
>but have not had time yet. But what parameters you used in
>my.cnf? You have a lot of RAM in your system, and you could make
>the Innobase buffer pool big.
I've tested with the default innobase parameters mentioned in the
documentation.
>
>>1. cat test.sql | mysql innobase => 306 seconds
>>2. cat test.sql | mysql innobase, but with autocommit=0 and all inserts
>>between BEGIN/COMMIT => 124 seconds
>
>If you use autocommit = 1, then Innobase has to flush the log to disk after
>each individual insert, which makes it slow. It is better to use autocommit
= 0,
>if you have enough space in your tablespace for the rollback segment.
ok, I understand.
>>3. same as 1. but with index creation after the inserts. => 264 seconds +
>>additional 59 seconds for index recreation.
>>4. same as 2. but with index creation after the inserts. => 75 seconds +
>>additional 59 seconds for index recreation.
>
>How do you create the index? With ALTER TABLE?
yes, exactly.
>>I noticed that in 3. and 4. the machine load was constantly at 100% during
>>the inserts.
>>but during index recreation the load springs wildley between 0 and 100%,
so
>>the machine is not maxed out in terms of CPU utilization here (in other
>
>Innobase has to write to the log which causes some disk i/o, reducing
>CPU utilization. Also, when the database has written the log files
>full, Innobase has to make a checkpoint, that is, flush written pages
>from the buffer pool. You could try making your log files very big, say
>150 MB in total, to get a better CPU utilization, and also the buffer pool
>bigger, if it is not yet big.
ok, I will try the benchmark with tweaked values for innobase again.
>
>Totally the opposite of spam! I got useful information from this!
ok, thanks ! I didn't read the mysql-mailinglist for a while, so I feared
"RTFM" as a reply to my posting :-)
--Andy
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