Robert Haas escribió:
> On Wed, Dec 16, 2009 at 10:29 AM, Andres Freund <andres@anarazel.de> wrote:
> > On Wednesday 16 December 2009 16:24:42 Robert Haas wrote:
> >> > Inserts and deletes follow the same protocol, obtaining an exclusive
> >> > lock on the row after the one being inserted or deleted. The result
> >> > of this locking protocol is that a range scan prevents concurrent
> >> > inserts or delete within the range of the scan, and vice versa.
> >> >
> >> > That sounds like it should actually work.
> >>
> >> Only if you can guarantee that the database will access the rows using
> >> some particular index. If it gets to the data some other way it might
> >> accidentally circumvent the lock. That's kind of a killer in terms of
> >> making this work for PostgreSQL.
> > Isnt the whole topic only relevant for writing access? There you have to
> > access the index anyway.
>
> Yeah, I guess you have to insert the new tuple. I guess while you
> were at it you might check whether the next tuple is locked...
So you'd have to disable HOT updates when true serializability was
active?
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
