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Redundant index is not always bad

 | August 28, 2007 |  Posted In: Benchmarks, Insight for DBAs

About year ago Peter wrote about redundant indexes and mentioned sometimes it is good to leave two indexes, even one is first part of another. I’m speaking about BTREE indexes, for example, KEY (A), and KEY (A,B). From SQL point of view KEY(A) is not needed, as for queries like WHERE A=5 the index (A,B) […]

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Memory allocation in Stored Function

 | August 26, 2007 |  Posted In: Insight for DBAs

UPDATE : Post is not actual anymore Not so long time ago I had task to update string column in table with 10mil+ rows, and, as the manipulation was non-trivial, I decided this task is good to try Stored Function. Function written – go ahead. Since 5 min I got totally frozen box with no […]

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Should MySQL Extend GROUP BY Syntax ?

 | August 17, 2007 |  Posted In: Insight for Developers

Jan has a good article about finding the row matching some value in the group: This is one illustration of group by limitations in SQL language which is not offset by any MySQL specific extensions,yet As you can see if you want to get one row from the group which is sorted some way you […]

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