In the last episode (Nov 11), Greg Matthews said:
>
> hey, can i hijack my message back?...this thread is about the performance of
> subselects, not stored procedures. go write your own message :-)...
>
> so....the original question is if someone would be nice enough to answer..
>
> ====> Do any MySql coders writing subselects in 4.1 know whether EXISTS will
>outperform an equivalent query written as a join. <=====
>
> Typically, db vendors recommend you use an exists clause, not a join
> when testing for the presence of child data because it's faster.
I would expect that the explain plans for both queries would end up
being identical, so the only difference is whichever you think is more
readable.
I don't remember reading any Oracle documentation recommending
subselects.
--
Dan Nelson
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