Re: [HACKERS] OR clause status
От | Bruce Momjian |
---|---|
Тема | Re: [HACKERS] OR clause status |
Дата | |
Msg-id | 199808051645.MAA05327@candle.pha.pa.us обсуждение исходный текст |
Ответ на | Re: [HACKERS] OR clause status (David Hartwig <daveh@insightdist.com>) |
Список | pgsql-hackers |
> Bruce Momjian wrote: > > > I have worked with Vadim privately on the remaining OR clause index > > issues, and I am done. Please start testing, everyone. > > > > Ran a few tests last night. So far, works great for single, non-internal, > attributes. However, I was not able to get the query to use the table's oid > index when such an index existed. Did a VACUUM ANALYZE before the query. > Will be doing some more testing over the next few days. Try: test=> explain select * from test where oid = 3::oid or oid = 4::oid; NOTICE: QUERY PLAN: Index Scan using i_test2 on test (cost=4.10 size=1 width=4) Thomas will have to deal with this before 6.4. The auto-casting of type oid is not working. > > Have not tried any mult-part keys. Will this patch handle a small number of > OR'ed multi-part keys? This is another item that I think does not work. The code handles AND and OR separately, making this hard to handle: key1 = 7 and (key2 = 99 or key2 = 100) It will use the first part of the key to get key1 = 7, but recognize that the first part of the key was matches and use the key2 part. I am going to study the optimizer code for 6.4, so I may be able to get it working. Not sure yet. It will certainly use the first part of a multi-part key if the first key is the one matching the OR clause. -- Bruce Momjian | 830 Blythe Avenue maillist@candle.pha.pa.us | Drexel Hill, Pennsylvania 19026 + If your life is a hard drive, | (610) 353-9879(w) + Christ can be your backup. | (610) 853-3000(h)
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