David Fetter <david(at)fetter(dot)org> writes:
> I think this page should mention that the expressions used in an
> expressional index need to be equivalent to an IMMUTABLE function, and
> the docs don't say so.

Sure they do, see CREATE INDEX:

	All functions and operators used in an index definition must be
	"immutable" ...

			regards, tom lane

In response to

• Missing information on Expressional Indexes at 2010-03-17 00:14:01 from David Fetter

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