Re: Re: Any optimizations to the join code in 7.1?
От | Tom Lane |
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Тема | Re: Re: Any optimizations to the join code in 7.1? |
Дата | |
Msg-id | 15130.988644136@sss.pgh.pa.us обсуждение исходный текст |
Ответ на | Re: Any optimizations to the join code in 7.1? (Thomas Lockhart <lockhart@alumni.caltech.edu>) |
Список | pgsql-hackers |
Thomas Lockhart <lockhart@alumni.caltech.edu> writes: > But it is possible, under many circumstances, for query optimization to > be a benefit for a many-table query. The docs indicate that explicit > join syntax bypasses that, even for inner joins, so you may find that > this syntax is a net loss in performance depending on the query and your > choice of table order. > Presumably we will be interested in making these two forms of inner join > equivalent in behavior in a future release. Tom, what are the > impediments we might encounter in doing this? I don't think there are any real technical problems in the way; it's simply an implementation choice not to treat INNER JOIN the same as an implicit join list. I did it that way in 7.1 mainly as a flyer, to see how many people would think it's a feature vs. how many think it's a bug. The votes aren't all in yet, but here we have Mike apparently pretty pleased with it, while I recall at least one other person who was not happy with the 7.1 behavior. regards, tom lane
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