Re: Trouble with explicit joins
От | Dmitry Tkach |
---|---|
Тема | Re: Trouble with explicit joins |
Дата | |
Msg-id | 41784809.4070009@openratings.com обсуждение исходный текст |
Ответ на | Re: Trouble with explicit joins (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | pgsql-sql |
Tom Lane wrote: >Dmitry Tkach <dmitry@openratings.com> writes: > > >>I suppose, this is because the planner takes the order, in which the >>tables appear in the explicit joins as some kind of a hint to how I want >>that query to be executed, >> >> > >It's not a "hint", it's a requirement. In general, changing the order >in which outer joins are executed changes the results. > >There are some cases in which it is safe to rearrange the order, but >determining this takes close analysis of the join conditions, and we >don't (yet) have any code to do that. So the planner must be >conservative and take your join order as gospel. > > regards, tom lane > > Yeah.. that's what I figured. Are you saying there is no way around it at all? Isn't there a syntax supported to write a left join with implicit joins?
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