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Re: index not being pick up
Posted by: Øystein Grøvlen
Date: January 19, 2018 07:26AM

Hi,

It is the presence of an OR expression that causes the optimizer to not use the index. You could try to split the OR expression using a UNION query, but then the view would probably not be merged, but instead stored in a temporary table which could potentially be very large.

For the given query, I think the best would be to reverse the column of the index. That is, create an index on (reference, scope_id).

Øystein Grøvlen,
Senior Principal Software Engineer,
MySQL Group, Oracle,
Trondheim, Norway

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