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author | akrus <akrus@flygroup.st> | 2013-02-04 14:13:38 +0400 |
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committer | akrus <akrus@flygroup.st> | 2013-02-04 14:13:38 +0400 |
commit | bb61951098fb71c43d2f606727d43d22c729089f (patch) | |
tree | efdaf1efa3f8c2107dde83ff2d615d5eb5974e36 /tools | |
parent | 524291493e64196d8ce02f4b637ea0ee1a176d0a (diff) | |
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Getting rid of unused indexes.
Source: http://dev.mysql.com/doc/refman/5.5/en/multiple-column-indexes.html
If the table has a multiple-column index, any leftmost prefix of the index can be used by the optimizer to find rows. For example, if you have a three-column index on (col1, col2, col3), you have indexed search capabilities on (col1), (col1, col2), and (col1, col2, col3).
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