On 6/3/07, David Krings <[EMAIL PROTECTED]> wrote:
Adrian Noland wrote: > The key to speedy SQL is in the indexes. Without an index the SQL engine > iterates over every row. With an index it automagically grabs the > correct value. This is really an eyeopener. After indexing all those columns that come up in some selects running the same query that took over 30 minutes (that's when I hit the reset button) now takes 26 seconds. This is plain awesome! Thanks for making me less dumb. David
When it comes to choosing which columns to index, you want to pick something with a high cardinality, or, for lack of a better term, "uniqueablity". Gender wont have a high cardinality because there are only 2 choices for many records. Last name on your personal family address book will have a low cardinality because of family members sharing last name. A key of last name + first name will have a high cardinality and will make a good index.
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