Useful things to know about MySQL 4

Max Kanat-Alexander mkanat at
Sun Jul 10 19:00:41 UTC 2005

	So, as many of us know, we will soon be requiring MySQL 4.0 for
Bugzilla to run. (Actually, at least 4.0.2 and perhaps some higher

	Here's a few things that are good to know about MySQL 4:

	+ It has a query cache, but it doesn't work for "server-side prepared
statements," per the MySQL docs. I'm not quite sure how this works with
DBI, perhaps somebody else knows?

	+ It supports UNION. So does PostgreSQL, so we can use UNION if it's
necessary or makes life simpler. I know that PostgreSQL basically treats
a UNION as two independent queries, performance-wise; I suspect MySQL
does the same, but I'm not sure how it will use indexes in a UNION.

	+ It has an expanded DELETE syntax that allows you to DELETE from
multiple tables at once. I'm not sure how PostgreSQL is on this, but I
suspect it probably works equally well on PostgreSQL.

	If you aren't familiar with what any of these things are, feel free to
ask me here or in IRC and I'll try to explain.

	There are also some other useful features in MySQL4. You can see all
the changelogs here:

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