"Gokulakannan Somasundaram" <gokul007@gmail.com> writes:
> On 10/9/07, Gokulakannan Somasundaram <gokul007@gmail.com> wrote:
>
>> A function is said to be deterministic, if it returns the same value,
>> irrespective of how many times, it is invoked. I think this definition
>> clearly puts the random function under the non-deterministic category. If we
>> have such a classification, do you think we can resolve this issue?
>
> If we frame a set of guidelines/test procedure, do you think it might solve
> the issue? Even, if we don't allow this type of indexing to anything other
> than built-in deterministic functions, i feel it would serve most of the
> indexing requirements.
We already do this. c.f. IMMUTABLE at
http://www.postgresql.org/docs/8.2/interactive/xfunc-volatility.html
and
http://www.postgresql.org/docs/8.2/interactive/sql-createindex.html
-- Gregory Stark EnterpriseDB http://www.enterprisedb.com