Thanks to everyone reply ..
I should have done a bit more research first , I had another index combining (GroupId,MemberId) that must have been added by me/some one in my organisation, and I wrongly assumed that RT created both indexes making the DisGrouMem (GroupId,MemberId,Disabled) useless. Been using RT for many years , lost track of what was done when and by whom ..

Once again thanks for all the replies

Regards;
Roy

Ian Pellew wrote:
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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