Re: COALESCE with single argument looks like identity function

Maksim Milyutin <maksim(dot)milyutin(at)tantorlabs(dot)ru> writes:
> I've noticed that COALESCE function doesn't converge to argument
> expression if it is alone in argument list of COALESCE as part
> simplification routine for expressions in planner. This might suppress
> further useful transformations when non-strict ops are required from
> some expression like converging OUTER JOIN to INNER one with WHERE qual
> containing COALESCE over single column from inner side.

Seems like a reasonable idea --- it's probably a rare case, but the
check is cheap enough. I'd add some comments though.

Please add this to the open commitfest so we don't lose track of it.

regards, tom lane