Обсуждение: Joining between large & small tables?

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Joining between large & small tables?

От
Wells Oliver
Дата:
Given a large large large table A and a small small temp table B is there any benefit to doing SELECT * FROM a JOIN b USING (somecol) vs SELECT * FROM b JOIN a USING (somecol)?

When you just want the intersection...

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Re: Joining between large & small tables?

От
Scott Ribe
Дата:
> On Jul 13, 2020, at 7:39 PM, Wells Oliver <wells.oliver@gmail.com> wrote:
>
> Given a large large large table A and a small small temp table B is there any benefit to doing SELECT * FROM a JOIN b
USING(somecol) vs SELECT * FROM b JOIN a USING (somecol)? 
>
> When you just want the intersection...

No, planner will figure out how to join based on stats, not order. (With default planner options; there are ways to
workaround that in the rare case that the planner can't figure out the best way.) 


Re: Joining between large & small tables?

От
"David G. Johnston"
Дата:
On Mon, Jul 13, 2020 at 6:40 PM Wells Oliver <wells.oliver@gmail.com> wrote:
Given a large large large table A and a small small temp table B is there any benefit to doing SELECT * FROM a JOIN b USING (somecol) vs SELECT * FROM b JOIN a USING (somecol)?


David J.