Horton

Re: SIREAD lock versus ACCESS EXCLUSIVE lock

Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>

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From: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
To: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Cc: Dan Ports <drkp@csail.mit.edu>, pgsql-hackers@postgresql.org
Date: 2011-04-27T20:24:42Z
Lists: pgsql-hackers 
On 27.04.2011 22:59, Kevin Grittner wrote:
> For correct serializable behavior in the face of concurrent DDL
> execution, I think that a request for a heavyweight ACCESS EXCLUSIVE
> lock might need to block until all SIREAD locks on the relation have
> been released.  Picture, for example, what might happen if one
> transaction acquires some predicate locks, then commits (releasing
> its heavyweight lock on the table), and before concurrent READ WRITE
> transactions complete there is a CLUSTER on the table. Or a DROP
> INDEX.  :-(

Hmm, could we upgrade all predicate locks to relation-level predicate 
locks instead?

-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com