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marko authored
Unfortunately, the patch seems to prevent MySQL from utilizing secondary indexes in the ORDER BY clauses. Thus, the test no longer checks if newly created indexes are well-formed. ChangeSet@1.2528.98.1 2007-08-02 12:45:56-07:00 igor@mysql.com Fixed bug#28404. This patch adds cost estimation for the queries with ORDER BY / GROUP BY and LIMIT. If there was a ref/range access to the table whose rows were required to be ordered in the result set the optimizer always employed this access though a scan by a different index that was compatible with the required order could be cheaper to produce the first L rows of the result set. Now for such queries the optimizer makes a choice between the cheapest ref/range accesses not compatible with the given order and index scans compatible with it.
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