[rt-users] DisGrouMem index

Ian Pellew ipellew at yahoo.com
Wed Apr 14 10:09:05 EDT 2010


>From my experience with compound indexes (Informix), the optimiser will use the leading component of the compound, thereafter, it would force a scan of the table.
The column 'disabled' is in the compound, and very likely not be the first component and hence, a forced a scan.
Drop the index and you would deprive queries of the first component as an index.
This would be quite painfull if the first was used as a "join" component, and probably is.

>> Is the index  DisGrouMem (GroupId,MemberId,Disabled) required for 3.8
>
>I wouldn't recommend it.

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