Re: [HACKERS] RE: [GENERAL] Long update query ? (also Re: [GENERAL] CNF vs. DNF)
От | Bruce Momjian |
---|---|
Тема | Re: [HACKERS] RE: [GENERAL] Long update query ? (also Re: [GENERAL] CNF vs. DNF) |
Дата | |
Msg-id | 199810060223.WAA24245@candle.pha.pa.us обсуждение исходный текст |
Ответ на | Re: [HACKERS] RE: [GENERAL] Long update query ? (also Re: [GENERAL] CNF vs. DNF) (David Hartwig <daveh@insightdist.com>) |
Список | pgsql-hackers |
> (A AND B) OR (C AND D) ==> (A AND B) UNION (C AND D) > > The rules to qualify are fairly strict. Must be have ANDs; rectangular in > shape; all (VAR op CONST) type nodes; minimum of 10 nodes; etc. I was > targeting the keysets queries generated by ODBC tools. > > As for the current direction this thread is going, (factoring) I have one > word of caution. PREPARE. If you take this route, you will never be able > to implement a workable PREPARE statement. I believe that in order for > PostgrerSQL ever become a industrial strength client/server it must implement > a PREPARE statement with parameters. I see that adding nodes it going to mess up prepare, but we already add extra nodes as part of part of "col in (1, 2, 3)." I think the PARAM's we already use will be duplicated/removed and still retain their values for substitution. They just may be in a different order. -- Bruce Momjian | http://www.op.net/~candle maillist@candle.pha.pa.us | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026
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