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Re: mysql 5.5.9 dreadfully slow
Posted by: Rick James
Date: February 21, 2011 05:51PM

innodb_buffer_pool_size (5.1->5.5): 260MB->100MB -- probably not significant, but could be.
sync_binlog: off -- no impact
innodb_doublewrite -- ON in both
trx_commit -- 1 in both
log file/buffer sizes -- bigger; seems like that would not hurt.
io_tickets -- bigger, so 5.5 should be able to handle more traffic.
max_dirty_page_pct -- 90% -> 75% -- a big change, but can't imagine that it would cause your problem.
sync_spin_lock_loops -- 20->30 ?

key_buffer_size -- 16MB -> 55MB -- might help if you have large MyISAM indexes

general_log -- ON -> OFF -- ?? ON would have slowed down 5.1 ??
log_bin -- Ditto ??

show STATUS like 'Qc%'

Do SHOW CREATE TABLE on both 5.1 and 5.5. I would like to know the Engine, and would like to know if it was the same engine on both.

4GB of RAM on 5.5; how much on 5.1? None of the settings seem too large for a 4GB machine.

VMs can have a large overhead for I/O -- were either of your timings on a VM?

I see no clues that could explain a 60x performance difference.

Recommend you post your stored procedure and accompanying data on bugs.mysql.com. Be sure to specify whether it is MyISAM or InnoDB.

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