| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Jan de Visser <jan(at)de-visser(dot)net> |
| Cc: | PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, bxzhai2010(at)gmail(dot)com, Kang Yuzhe <tiggreen87(at)gmail(dot)com> |
| Subject: | Re: SQL MERGE patches for PostgreSQL Versions |
| Date: | 2017-06-22 17:08:34 |
| Message-ID: | CAH2-WzmhL_e0s6vQkGY-b4ETNto0dCaXbV60BVr2GAH4v5c44Q@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Jun 22, 2017 at 9:52 AM, Jan de Visser <jan(at)de-visser(dot)net> wrote:
> I am not quite sure what you're trying to achieve, but are you aware that
> pgsql 9.6 introduced the ON CONFLICT clause, which allows you to do the same
> with a different syntax?
>
> https://www.postgresql.org/docs/9.6/static/sql-insert.html
I don't think it's the same thing. I think we could reasonably have
both SQL MERGE and ON CONFLICT. Or at least, I think that that makes
sense. Teradata already has both (their own custom UPSERT syntax, plus
an implementation of SQL MERGE).
Boxuan Zhai's patch didn't try to do anything special about
concurrency. At the time, this was controversial. However, we now
understand that SQL MERGE really isn't obligated to handle that at all
[1]. Besides, we have ON CONFLICT for those use-cases.
[1] https://wiki.postgresql.org/wiki/UPSERT#MERGE_disadvantages
--
Peter Geoghegan
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