| From: | "Albe Laurenz" <laurenz(dot)albe(at)wien(dot)gv(dot)at> |
|---|---|
| To: | "Yelai, Ramkumar IN BLR STS *EXTERN*" <ramkumar(dot)yelai(at)siemens(dot)com>, "Moshe Jacobson" <moshe(at)neadwerx(dot)com> |
| Cc: | <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Parallel Insert and Delete operation |
| Date: | 2012-11-05 10:30:18 |
| Message-ID: | D960CB61B694CF459DCFB4B0128514C208A4E67C@exadv11.host.magwien.gv.at |
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| Thread: | |
| Lists: | pgsql-general |
Ramkumar Yelai wrote:
[is worried that a database might become inconsistent if conflicting
INSERTs and DELETEs occur]
> @Albe - I got you first point. The second point is little skeptical
because postgres could have been
> avoided this lock by using MVCC. Please correct me if I am wrong?
Which lock could have been avoided?
PostgreSQL locks rows when the data change.
That has little to do with MVCC.
If you INSERT into a table that has a foreign key, the
referenced row in the referenced table gets a SHARE lock
that conflicts with the EXCLUSIVE lock required for
a DELETE.
So they cannot execute concurrently.
Yours,
Laurenz Albe
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