From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
Cc: | Gregory Stark <stark(at)enterprisedb(dot)com>, PostgreSQL Development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Recursive query syntax ambiguity |
Date: | 2007-02-05 16:23:58 |
Message-ID: | 446.1170692638@sss.pgh.pa.us |
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Martijn van Oosterhout <kleptog(at)svana(dot)org> writes:
> However, I don't know it matters. You only need to cost the plan if
> there are alternate paths and given the plan structure is strongly
> constrained, I'm not sure how much it matters.
It does, since the whole thing could be a subquery, in which case there
could be options available at the outer level. I doubt we'll be able to
be really smart, but that doesn't mean we can just punt.
> In the case of read-committed mode, will two seq-scans always
> return the same result?
They definitely should, since we'll be using the same snapshot
throughout the query.
regards, tom lane
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