George Pavlov wrote: > the basic question i have is fairly clear though: why saying "where x = > 10" should be different (in ANY cicumstance, not just mine) from saying > "where x between 10 and 10" or from "where x in (select ... /* some > query that returns 10 */)" ???
I think the principle here is that the system is not gonna waste cycles on dumb queries. Supposedly, morphing "foo BETWEEN 10 and 10" into "foo=10" is not a trivial transformation, and it'd impose a planning cost on all non-dumb BETWEEN queries. That cost is best avoided: if you optimize for dumb users, the smart users then want you buried because you've lost performance doing useless work. -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support ---------------------------(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
