Peter Eisentraut wrote:
On Tuesday 06 January 2009 02:03:14 Tom Lane wrote:
I don't think there's a bug here, at least not in the sense that it
isn't Operating As Designed. But it does seem like we could do with
some more/better documentation about exactly how FOR UPDATE works.
The sequence of operations is evidently a bit more user-visible than
I'd realized.
Well, if the effect of ORDER BY + FOR UPDATE is "it might in fact not be
ordered", then it's pretty broken IMO. It would be pretty silly by analogy
for example, if the effect of GROUP BY + FOR UPDATE were "depending on
concurrent events, it may or may not be fully grouped".
I can see two ways forward:
1) We document bluntly that ORDER BY + FOR UPDATE can return unordered
results, or
2) We prohibit ORDER BY + FOR UPDATE, like we do with a number of other
clauses. (There would be no loss of functionality, because you can run
the query a second time in the transaction with ORDER BY.)
Comments?
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