Re: Avoiding sequential scans with OR join condition
От
Mike Mascari
Тема
Re: Avoiding sequential scans with OR join condition
Дата
Msg-id
4172193D.8030202@mascari.com
Ответ на
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Дерево обсуждения
Avoiding sequential scans with OR join condition Mike Mascari <mascarm@mascari.com>
Re: Avoiding sequential scans with OR join condition Sim Zacks <sim@compulab.co.il>
Re: Avoiding sequential scans with OR join condition Mike Mascari <mascarm@mascari.com>
Re: Avoiding sequential scans with OR join condition Mike Mascari <mascarm@mascari.com>
Re: Avoiding sequential scans with OR join condition Sim Zacks <sim@compulab.co.il>
Re: Avoiding sequential scans with OR join condition Bruno Wolff III <bruno@wolff.to>
Re: Avoiding sequential scans with OR join condition Martijn van Oosterhout <kleptog@svana.org>
Re: Avoiding sequential scans with OR join condition Janning Vygen <vygen@gmx.de>
Re: Avoiding sequential scans with OR join condition Tom Lane <tgl@sss.pgh.pa.us>
Sim Zacks wrote: > I would use 2 left joins and use the where condition to make sure one > of them is true, such as: > > select big_table.* from > big_table left join little_table as l1 on big_table.y1=l1.y and > l1.x=10 > left join little_table as l2 on big_table.y2=l2.y and l1.x=10 > where l1.p_key is not null and l2.p_key is not null > > I have never tried this in postgresql, but in my experience with > various other DB engines it is a lot faster then using an or in the > join and faster then a union. Wow! Thanks! That certainly did the trick. Mike Mascari
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