True, but here (and in Oracle and other DBs with this feature), it's not magical. That is, you have to decide ahead of time exactly what expression you want to index on and then make your WHERE conditions query on exactly that expression. That said, especially for simple things like case-insensitive comparison (by creating an index on LOWER(somecol) ) this feature can offer an enormous performance benefit in many cases.

In reply to Re^2: (OT) Don't blow that index dude. by Errto
in thread (OT) Don't blow that index dude. by demerphq

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