Re: Support Parallel Query Execution in Executor - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Support Parallel Query Execution in Executor
Date
Msg-id 12625.1144607981@sss.pgh.pa.us
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In response to Re: Support Parallel Query Execution in Executor  ("Jonah H. Harris" <jonah.harris@gmail.com>)
Responses Re: Support Parallel Query Execution in Executor  ("Jonah H. Harris" <jonah.harris@gmail.com>)
List pgsql-hackers
"Jonah H. Harris" <jonah.harris@gmail.com> writes:
> On 4/9/06, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I was considering a variant idea in the shower this morning:suppose
>> that we invent one or more "background reader" processes that have
>> basically the same infrastructure as the background writer, but have
>> the responsibility of causing buffer reads to happen at useful times

> This is sort of what I'm playing with.  There are N-number of backends
> which are configured at startup and are available solely for parallel
> processing.

That's not remotely the same thing: a backend is a very different animal
from a bgwriter.  In particular, bgwriter (and bgreaders if we had 'em)
aren't database-specific, don't need to think about permission checking
as they don't execute on behalf of particular users, don't have syscaches
to keep in-sync with everything else, etc etc.
        regards, tom lane


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