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Data not being retrieved from index

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  • Data not being retrieved from index

    Hello!

    My name is Claudio Garcia and I'm new to this forum. I would appreciate your help with the following problem.

    I have a table with 5 columns, all of them integers, except column C, which is type text. I have the following query:


    EXPLAIN SELECT D, E FROM some_table WHERE A = 1 AND B = 1 AND C IS NOT NULL;
    And the following index:


    KEY( A, B, C(1), D, E )

    The index works fine to find the rows, but I include D and E in the index so that they can be retrieved from the index instead of being read from disk.

    The problem is that D and E won't be retrieved from the index.

    So MySQL can use the index to find which rows have a non-null value in C, but it cannot retrieve D and E from the index, even though they're in it. Is this a bug in MySQL?

    If I make C be an integer type, then it works as expected.

    Thanks in advance!

    Claudio
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