Re: Using regular expressions in LIKE

Karsten Hilbert  writes:
>> Regexes are optimized the same way as equivalent LIKE expressions.  In
>> particular, the pattern has to be left-anchored to consider using it
>> with an index.  In LIKE that means no wildcard at the start of the
>> pattern, in regex it means there has to be a ^.

> What about "^.*oobar" in a regex ? I mean, it seems impossible
> to use an index on that, right ?

Right.  You need ^ immediately followed by some constant text.  The
planner extracts the "fixed prefix" of the pattern to use with the index.

			regards, tom lane