From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Jeff Davis <pgsql(at)j-davis(dot)com> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: return next |
Date: | 2005-11-11 14:57:16 |
Message-ID: | 18533.1131721036@sss.pgh.pa.us |
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Lists: | pgsql-general |
Jeff Davis <pgsql(at)j-davis(dot)com> writes:
> From the docs on plperl:
> "Usually you'll want to return rows one at a time, both to speed up
> startup time and to keep from queueing up the entire result set in
> memory. You can do this with return_next as illustrated below."
> Am I misunderstanding the docs? How do I just return one tuple at a time
> without PostgreSQL continuing the loop?
The docs are perhaps a little misleading. The perl function will
execute to completion in any case --- it's hard to see how to prevent
that from happening without breaking perl. The point of the comment
is that with return_next, buffering of the result set happens in a
TupleStore object (which knows how to spill an oversize set to disk)
rather than inside perl (which doesn't).
regards, tom lane
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