Re: [GENERAL] Problem (bug?) with like
От | Bruce Momjian |
---|---|
Тема | Re: [GENERAL] Problem (bug?) with like |
Дата | |
Msg-id | 200112281835.fBSIZg129445@candle.pha.pa.us обсуждение исходный текст |
Ответ на | Re: [GENERAL] Problem (bug?) with like (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: [GENERAL] Problem (bug?) with like
|
Список | pgsql-hackers |
> Bruce Momjian <pgman@candle.pha.pa.us> writes: > > But what about '%A%' vs. '%AC%'. Seems the second is reasonably > > different from the first the our optimizer may be fine with that. Is it > > only when the strings get longer that we lose specificity? > > Yeah, I don't think that the estimates are bad for one or two > characters. But the estimate gets real small real fast as you > increase the number of match characters in the LIKE pattern. > We need to slow that down some. See my earlier email about the 50% idea for LIKE. Do ordinary string comparisons also have this problem? -- Bruce Momjian | http://candle.pha.pa.us pgman@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
В списке pgsql-hackers по дате отправления: