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How many partitions can you have ?

 | December 5, 2009 |  Posted In: Benchmarks, Insight for DBAs, MySQL

I had an interesting case recently. The customer dealing with large MySQL data warehouse had the table which was had data merged into it with INSERT ON DUPLICATE KEY UPDATE statements. The performance was extremely slow. I turned out it is caused by hundreds of daily partitions created for this table. What is the most […]

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Rare evil MySQL Bug

 | November 20, 2009 |  Posted In: Insight for DBAs, MySQL

There is the rare bug which I ran into every so often. Last time I’ve seen it about 3 years ago on MySQL 4.1 and I hoped it is long fixed since… but it looks like it is not. I now get to see MySQL 5.4.2 in the funny state. When you see bug happening […]

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Crashes while using MyISAM with multiple key caches

 | July 18, 2009 |  Posted In: Insight for DBAs

Over last couple of years I have ran into random MySQL crashes in production when multiple key caches were used. Unfortunately this never was frequent or critical enough issue so I could spend time creating repeatable test case and search of the bug in the MySQL database did not find anything. Recently we had this […]

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Funniest bug ever

 | January 31, 2009 |  Posted In: Events and Announcements

Recently my attention was brought to this bug which is a nightmare bug for any consultant. Working with production systems we assume reads are reads and if we’re just reading we can’t break anything. OK may be we can crash the server with some select query which runs into some bug but not cause the […]

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AUTO_INCREMENT and MERGE TABLES

 | September 11, 2008 |  Posted In: Insight for DBAs

How would you expect AUTO_INCREMENT to work with MERGE tables ? Assuming INSERT_METHOD=LAST is used I would expect it to work same as in case insertion happens to the last table… which does not seems to be the case. Alternatively I would expect AUTO_INCREMENT to be based off the maximum value across all tables, respecting […]

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Beware of running ANALYZE in Production

 | September 2, 2008 |  Posted In: Insight for DBAs

As you might know ANALYZE TABLE just quickly updates table statistics using index dives, unlike with MyISAM when it scans indexes holding table lock for long period of time. So ANALYZE TABLE should be very fast and non intrusive operation doing just little update on the data. Right ?

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