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I wanted to know that If I index a varchar field say 'name' and then run a query say "Select * from tablename where name in ('gg','hh','jj')" and if the table has say 'N' rows, will the condition be checked for all N rows or does mysql somehow becoz of indexing manage to perform the operation by lesser than N checks.
Oct 22 '06 #1
1 1087
miller
1,089 Recognized Expert Top Contributor
The quick answer to your question is "yes".

You will have to decide how many characters that you actually want to index though. Having too many characters on a varchar can mean a really huge index size. Having too few can mean that the index really isn't doing very much to speed up efficiency. I would suggest the random number of 8 characters for most fields.

Finally, after you've created your index, be sure to run "EXPLAIN" on your sql queries. This will tell you which indexes are actually being utilized.
Oct 23 '06 #2

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