Re: Serious performance problem
От | Zeugswetter Andreas SB SD |
---|---|
Тема | Re: Serious performance problem |
Дата | |
Msg-id | 46C15C39FEB2C44BA555E356FBCD6FA41EB3E6@m0114.s-mxs.net обсуждение исходный текст |
Ответ на | Serious performance problem ("Tille, Andreas" <TilleA@rki.de>) |
Список | pgsql-hackers |
> > so it's linear growth here > This is what my colleague was afraid of: We would have linear growth > compared to the log(n) growth which is to be expected on MS SQL server This is not true, since the index scan also neads to read the leaf pages in MS Sql. The number of leaf pages grows linear with number of rows that qualify the where restriction. R = number of rows that qualify --> O(R + log(R)) The pg measurements showed, that PostgreSQL query performance can be expected to stay nearly the same regardless of number of rows in the table as long as the number of rows that qualify the where restriction stays constant. The response time is linear to the number of rows that qualify the where restriction, but that linear behavior is also expected with MS Sql. Andreas
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