| Data not being retrieved from index [message #1762] |
Fri, 07 September 2007 17:30 |
 claudiogarcia
Messages: 1
Registered: September 2007 |
Junior Member |
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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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