Hi!
I have a 650000 records table with several fields, in MaxDB 7.5.0.24 for linux. Work pretty well.
But, if I issue:


select * from mytable where mydescription like 'something%'

the execution plan uses the index containing mytable.mydescription, and take near to 2,07 secs. Good performance, good choice.
But the following is very slow:


select * from mytable where mydescription like '%something%'

For this query, the execution plan doesn't uses the index containing mytable.mydescription, and take near to 68,09 secs (~32 times slower).
Why the "explain" says index use for first query, and a table scan for the second?
Why can't execution plan uses the index for %something% searches as it does for something%? I don't think something will be lost, except performance.


Is this a configuration?

Thanks for any tips.

--
Edson Carlos Ericksson Richter
MGR Inform�tica Ltda.
Fones: 3347-0446 / 9259-2993


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