"Gokulakannan Somasundaram" <[EMAIL PROTECTED]> writes: > On 10/9/07, Gokulakannan Somasundaram <[EMAIL PROTECTED]> 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 ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
