All, 

How hard would it be to get a back end to hand off parts of a query tree to
other back ends (which it created), and then collate the results, and take
it from there?  Obviously, it would only do this under certain conditions,
specifically, if it was compiled in to the server, and the query tree in
question had a particular profile, i.e.: lent itself to parallel processing.
But surely it couldn't be that difficult to get a back end to hand off, say,
a sub-select sub-tree, or UNION sub-trees.  Under heavy loads with the right
hardware, this could gain significant performance improvement.


Michael Ansley



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Parallel queries


All, 

How hard would it be to get a back end to hand off parts of a query tree to other back ends (which it created), and then collate the results, and take it from there?  Obviously, it would only do this under certain conditions, specifically, if it was compiled in to the server, and the query tree in question had a particular profile, i.e.: lent itself to parallel processing.  But surely it couldn't be that difficult to get a back end to hand off, say, a sub-select sub-tree, or UNION sub-trees.  Under heavy loads with the right hardware, this could gain significant performance improvement.

Michael Ansley



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Wed, 31 Jan 2001 14:18:57 -0000
Michael Ansley <Michael.Ansley@intec-telecom-systems.com>
Parallel queries
> How hard would it be to get a back end to hand off parts of a query
> tree to other back ends (which it created), and then collate the
> results, and take it from there?  Obviously, it would only do this
> under certain conditions, specifically, if it was compiled in to the
> server, and the query tree in question had a particular profile, i.e.:
> lent itself to parallel processing.  But surely it couldn't be that
> difficult to get a back end to hand off, say, a sub-select sub-tree,
> or UNION sub-trees.  Under heavy loads with the right hardware, this
> could gain significant performance improvement.

Right. This would help speed up some single-client queries on SMP
machines (we already scale will with multiple clients on SMP machines).
This could perhaps be solved by threading each client backend, or, as
you suggest, by spawning entirely new processes (which would easily ??
generalize into distributed database support). Bring it up after 7.1 is
released (though there may be enough hoops to jump through that it would
not be in 7.2; not certain yet).

All imho of course, though we've had a few discussions off-list to help
get us thinking about it for planning purposes.

I would assume that it will take a few folks working together to get
this to fly, but feel free to give it a go on your own.

                      - Thomas

Tue, 06 Feb 2001 05:02:55 +0000
Thomas Lockhart <lockhart@alumni.caltech.edu>
Re: Parallel queries