Re: Surfacing qualifiers - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Surfacing qualifiers
Date
Msg-id 29678.1206552074@sss.pgh.pa.us
Whole thread Raw
In response to Re: Surfacing qualifiers  (David Fetter <david@fetter.org>)
Responses Re: Surfacing qualifiers
List pgsql-hackers
David Fetter <david@fetter.org> writes:
> What happens now with dblink is that the remote table (more generally,
> the output of a fixed query) gets materialized into memory in its
> entirety, and if it's bigger than what's available, it will crash the
> backend or worse.

This is utter nonsense.  It gets put into a tuplestore which is entirely
capable of spilling to disk.  Slow, yes, but crashing is a lie.

> That happens because functions do not have any
> access to the predicates with which they were called, so the current
> workaround is to pass the predicates manually and then cast.

dblink is not a suitable framework for improving that situation.
Maybe someday we'll have a proper implementation of SQL/MED ...
        regards, tom lane


pgsql-hackers by date:

Previous
From: Kenneth Marshall
Date:
Subject: Re: [GSoC] Need for advice on improving hash index performance
Next
From: David Fetter
Date:
Subject: Re: Surfacing qualifiers