mysql like performance boost
is there anyway to speed 开发者_开发技巧up mysql like operator performance if wild card is involved? eg. like '%test%'
MySQL can use an index if your query looks like foo LIKE 'abc%'
or foo LIKE 'abc%def%'
. It can use the index for any portion or the string before the first wildcard. If you need to match a word anywhere within a string, you might want to consider using FULLTEXT
indexes instead.
More detail on indexes: http://dev.mysql.com/doc/refman/5.1/en/mysql-indexes.html
Full text search: http://dev.mysql.com/doc/refman/5.0/en/fulltext-search.html
Well, the simplest optimization would be to have a constant prefix (e.g. "test%"
instead of "%test"
or "%test%"
) since that would allow the engine to narrow down the search space using indices. However, that is not possible in all situations.
Sometimes a preprocessing step can turn a wildcard search into an ordinary equality or a fulltext search. You'll gain more by finding a way to structure your data so that it does not require a wildcard search than trying to optimize the latter.
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