Re: [HACKERS] Re: [BUGS] General Bug Report: Bug in optimizer
От | Bruce Momjian |
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Тема | Re: [HACKERS] Re: [BUGS] General Bug Report: Bug in optimizer |
Дата | |
Msg-id | 199903181846.NAA05726@candle.pha.pa.us обсуждение исходный текст |
Ответ на | Re: [HACKERS] Re: [BUGS] General Bug Report: Bug in optimizer (Vadim Mikheev <vadim@krs.ru>) |
Ответы |
Re: [HACKERS] Re: [BUGS] General Bug Report: Bug in optimizer
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Список | pgsql-hackers |
> Bruce Momjian wrote: > > > > Let me tell you why I don't think this is a bug. The optimizer will > > choose ordered results over unordered results if the costs are the same. > > In this case, the cost of the query is zero, so it chose to use the > > index because the index produces an ordered result. > > > > This works well for un-vacuumed tables, because it thinks everything is > > zero cost, and chooses the index. > > Agreed, this is ok as long as > > vac=> create table table1 (field1 int); > CREATE > vac=> insert into table1 values (1); > INSERT 1583349 1 > vac=> create index i_table1__field1 on table1 (field1); > CREATE > vac=> explain select * from table1 where field1 = 1; > NOTICE: QUERY PLAN: > > Seq Scan on table1 (cost=1.03 size=1 width=4) > > - SeqScan is used for small tables. > > So, only bug reported is left. > Can you get on IRC now? Why are you up so late? -- 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, Pennsylvania19026
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