Re: BUG #12000: "CROSS JOIN" not equivalent to ","
От | Tom Lane |
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Тема | Re: BUG #12000: "CROSS JOIN" not equivalent to "," |
Дата | |
Msg-id | 13989.1416333351@sss.pgh.pa.us обсуждение исходный текст |
Ответ на | Re: BUG #12000: "CROSS JOIN" not equivalent to "," (David G Johnston <david.g.johnston@gmail.com>) |
Ответы |
Re: BUG #12000: "CROSS JOIN" not equivalent to ","
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Список | pgsql-bugs |
David G Johnston <david.g.johnston@gmail.com> writes: > Tom Lane-2 wrote >> A simple "fix" would be to remove the claim about "," and just compare >> CROSS JOIN to INNER JOIN ON TRUE. I'm not really convinced that's an >> improvement ... > How about adding the following to that sentence: > "However, in the presence of three or more joined relations it is > recommended to only use either explicit joins or commas since mixing them > introduces non-obvious join order differences." I don't think it's the place of the manual to be prescriptive about style; at least, not here. We could do something like "<CROSS JOIN example> is equivalent to <INNER JOIN ON TRUE example>. <CROSS JOIN example> is also equivalent to <example with comma>, but in cases with more than two tables this equivalence is not exact, because JOIN binds more tightly than comma." Or maybe put the "but" in a footnote. regards, tom lane
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