On Thu, May 8, 2008 at 2:30 PM, Bryan Tong Minh
<bryan.tongminh(a)gmail.com> wrote:
I've heard rumours on #wikimedia-tech that MySQL 4
sometimes chooses
the wrong index unless forced.
*Every* database engine is going to make the wrong choice sometimes,
unless maybe it uses some kind of adaptive technique (I'm not an
expert on DBMSes). The question is only how often, and in which
particular cases? MySQL 4 will choose the wrong index sometimes when
MySQL 5 will not. (Possibly the converse is true as well.)
My approach is that if it chooses the right index for me, it's up to
Domas or someone to fix it if he sees it's broken on MySQL 4. :)