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For flyway ( CI integration tests on Jenkins (Ubuntu) we use a Windows XP image on VirtualBox 4.1 on which the the supported DBs (DB2, MySQL, PostgreSQL, Oracle, SQLServer) are installed. Everything works fine and we connect via virtualbox port forwarding feature to the DBs on the virtual machine.

But only for MySQL the simple test's run extremely slow (minutes instead of several seconds) and we had to raise the timeout to get them green.

The tests are running fast if a local MySQL instance is used.

Does anybody have an idea what may be the reason for this, or how we can track/analyze the problem?

Greets Chris

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Did you solve this? Was the VM 64bit? – cherouvim Mar 14 '14 at 8:27
  • Are the tables in the same format (MyISAM, InnoDB etc.) on both host and guest?
  • Do you have same indexes on tables created on both machines? Try running EXPLAIN <query> in mysql console to see and compare the results, especially if both queries use same indexes and in the same order.
  • Do you use subqueries? They tend to be very slow at times. In case of subqueries, try to rewrite them using JOINs.
  • See the configuration files (my.ini / my.cnf) and check if the settings are the same. Look especially at temporary tables / buffers sizes and that kind of things. There might be the case that MySQL has small amount of memory available.
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