Tom Lane <tgl@sss.pgh.pa.us> writes:
> I can see that there's a fair argument for that position in cases like
> the above, but the trouble is that there are also cases where it's very
> hard for the user to predict how many rows will be read. As examples,
> mergejoins may stop short of reading all of one input depending on what
> the last key value is from the other, and semijoins or antijoins will
> stop whenenever they hit a match in the inner input.
Oh. Indeed, I now understand what you mean by surprises. I keep
forgetting that DML and JOINs can live together…
Regards,
--
Dimitri Fontaine
http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support