Thread: UPDATE and INDEX on expensive function with (IsCachable)

Suppose some _cachable_ function f is expensive, but its results are
often needed.  So, to speed up queries, we have an index on
f(table.field). I wonder what happens when we update a tuple of that
table: will f be re-computed if table.field is not changed? What if
the update explicitly re-sets table.field to its old value?

Thanks in advance,

Albert.

"Albert REINER" <areiner@tph.tuwien.ac.at> writes:
> Suppose some _cachable_ function f is expensive, but its results are
> often needed.  So, to speed up queries, we have an index on
> f(table.field). I wonder what happens when we update a tuple of that
> table: will f be re-computed if table.field is not changed?

Yes.

            regards, tom lane