| From: | Peter Eisentraut <peter_e(at)gmx(dot)net> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-hackers(at)postgresql(dot)org, Josh Berkus <josh(at)agliodbs(dot)com>, Jaime Casanova <systemguards(at)gmail(dot)com> |
| Subject: | Re: someone working to add merge? |
| Date: | 2005-11-11 18:24:39 |
| Message-ID: | 200511111924.41532.peter_e@gmx.net |
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| Lists: | pgsql-hackers |
Tom Lane wrote:
> If you don't have any better idea how to do it than a full table
> lock, you might as well not do it at all. A "proof of concept" that
> doesn't solve the hard part of the problem is no proof :-(
But the problem here is not to break any kind of performance barrier,
but to give people migrating from MySQL and alternative for REPLACE
command.
> My first guess about a real implementation would involve extending
> the index AM API to offer a function "insert this key, or return the
> existing match if there already is one".
This assumes that there are indexes defined for the columns involved in
the merge condition, which is not required anywhere.
--
Peter Eisentraut
http://developer.postgresql.org/~petere/
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