Re: MERGE vs REPLACE

On Fri, Nov 11, 2005 at 03:42:38PM -0500, Tom Lane wrote:
> Peter Eisentraut <peter_e@gmx.net> writes:
> > It seems to me that it has always been implicitly assumed around here 
> > that the MERGE command would be a substitute for a MySQL-like REPLACE 
> > functionality.  After rereading the spec it seems that this is not the 
> > case.  MERGE always operates on two different tables, which REPLACE 
> > doesn't do.
> 
> Normally I'd plump for following the standard ... but AFAIR, we have had
> bucketloads of requests for REPLACE functionality, and not one request
> for spec-compatible MERGE.  If, as it appears, full-spec MERGE is also a
> whole lot harder and slower than REPLACE, it seems that we could do
> worse than to concentrate on doing REPLACE for now.  (We can always come
> back to MERGE some other day.)

I suspect a lot of those requests are from people who actually want
merge and don't realize that mysql has a replace.

On another note, is there any reason we can't put an equivalent to
example 36-1 (http://lnk.nu/postgresql.org/617.html) into the backend?
Presumably it wouldn't be as fast as a more elegant solution, but OTOH
it'd probably be faster than plpgsql...
-- 
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
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