On Mon, Jul 24, 2017 at 3:12 PM, Dmitry Lazurkin <dilaz03@xxxxxxxxx> wrote:
On 25.07.2017 00:31, David G. Johnston wrote:
This query uses JOIN plan node as IN (VALUES ...).
And I have one question. I don't understand why IN-VALUES doesn't use Semi-Join? PostgreSQL has Hash Semi-Join... For which task the database has node of this type?
I think it is simply because no one has gotten around to implementing it that way. When you can just write it as a values list instead, the incentive to make the regular in-list work better is not all that strong.
Cheers,
Jeff