MySQL Server Forum - Which index to hit first?

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Author

Which index to hit first?

rloef@interfold.com

2005-11-30, 8:23 pm

I have a multi-million row table with three indexes in MySQL-5.0.15.
These indexes have the following number of distinct values:

date 415

block 100000

scan 45

If I'm doing a query on this table in what order should I hit these
indexes? The largest first, to get rid of the most possibilities right
away? Or the smallest first, because it has the fewest number of rows
to scan to make the cut? At some level both seem to make sense, but I'm
doing smallest to largest. Is this the most efficient? Or is this a
case of just letting the query optimizer choose? I don't yet have a
compound index on these fields.

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