RE: [SQL] Good Optimization
От | Ansley, Michael |
---|---|
Тема | RE: [SQL] Good Optimization |
Дата | |
Msg-id | 1BF7C7482189D211B03F00805F8527F70ED012@S-NATH-EXCH2 обсуждение исходный текст |
Список | pgsql-sql |
> > > > Bruce Momjian wrote: > > >=20 > > > Added to TODO: > > >=20 > > > * In WHERE x=3D3 AND x=3Dy, add y=3D3 > > > > I don't know if I'm way off, but wouldn't removing "x=3Dy" improve > > performance further? > <snip some example stuff> > > IMHO we're improving optimization more and more on the cost > of query parse/rewrite/optimize/plan time. Thus performance > of statements that EXECUTE fast slows down more and more. > Isn't it time to think about some (maybe shared) > "parsetree->plan" cache that provides ready to use plans if > only Const values have changed? Isn't this what stored procs are supposed to be? If a stored proc is defined with parameters, then the query plan is saved, and the execution of the statement is saved the effort of having to recompile the plan. In fact, I think that SQL Server, and possibly Oracle as well, store the plan for any query sent, and then drop it when the connection is terminated. Perhaps this is something to think about. MikeA
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