Re: Stability and performance issue after 4.0 to 4.1 upgrade.

[Wolfgang Blauen]

Thanks for the input.

Yes, I was using 4.0.10 (for a long time and to a great level of satisfaction!).

I migrated the data three different ways:
- the first time I somply just updated the binaries - that didn't work right at all.
- the second time I recovered a 4.0 backup on a separate machine, used mysqldump to dump the database and then loaded it with the "mysql <database> <<dumpfile.sql>" and still got quite poor application performance.
- the third time I wrote an ODBC bridge that captures the "create table" for each table form the old database (4.0), creates a new table in the new database (4.1) and then loads the data from the old table to the new table record by record, field by field. The result was very similar to the first attempts.

I have since migrated the data back to the old 4.0.10 engine and got the good performance back. Having the desire to go with the technology, I would (naturally) like to upgrade to a newer version of MySQL and am therefore in the process of analyzing the issue. I am planning to develop a repeatable procedure to reproduce the issue and test on 4.0, 4.1 and 5.0 to determine the results on the different versions. At this point the issue seems to be less one of extreme slow down of an idiviual long running query as it appears that it may be an accumulation of response time increases on many small quesries in a short amount of time. I was hesitant to file a bug report at this time since I didn’t know if I’m looking at a real problem or just something I did wrong.

Since you are pointing out differences in the MyISAM engine I think I can explain some of the odd behavior when updating records that I described.

I haven't messed with the character set. That may be another option. Do you have any info on how I can chasnge that back to Latin1 instead of UTF8 ( a link would be fine).

Thanks again for the help.

More to come, soon.