"Tom Lane" <[EMAIL PROTECTED]> writes: > As an example, consider > t1 join t2 on (...) join t3 on (...) ... join t8 on (...) > and for simplicity suppose that each ON condition relates the new > table to the immediately preceding table, and that we can't derive > any additional join conditions through transitivity.
So the problem is that if we happen to have some x=<const> clause for any variable listed in those join clauses then we drop that clause entirely and end up delaying that join until the very end? So is the fact that the user provided a useless clause the only information we have that these tables might be related? So if I write (along with some other joins): t1 join t2 on (t1.x=t2.x) where t1.x=3 I'll get a different result than if I write t1, t2 where t1.x=3 and t2.x=3 ? Perhaps we could be going the other direction and trying to add redundant selectivity 1.0 clauses when we have multiple variables which come out to the same value? -- Gregory Stark EnterpriseDB http://www.enterprisedb.com Ask me about EnterpriseDB's Slony Replication support! ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
