Postgres Pro
Downloads
Home   >   mailing lists

Re: Sort returns more rows than seq scan? - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Sort returns more rows than seq scan?
Date
Msg-id 9409.1456843512@sss.pgh.pa.us
Whole thread Raw
In response to Sort returns more rows than seq scan?  (Pavel Stehule <pavel.stehule@gmail.com>)
Responses Re: Sort returns more rows than seq scan?  (Pavel Stehule <pavel.stehule@gmail.com>)
List pgsql-hackers
Tree view 
Pavel Stehule <pavel.stehule@gmail.com> writes:
> I don't understand how is possible to get more rows from Sort node than in
> nested seq scan?

The "extra" rows are re-fetches triggered by mark/restore requests from
the parent mergejoin.  The EXPLAIN instrumentation counts re-fetches as
if they were new rows.
        regards, tom lane

pgsql-hackers by date:

Previous
From: Julien Rouhaud
Date:
Subject: Re: Publish autovacuum informations
Next
From: Aleksander Alekseev
Date:
Subject: Re: Patch: fix lock contention for HASHHDR.mutex