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	id AA09962; Mon, 18 Nov 91 13:33:35 -0800
Message-Id: <9111182133.AA09962@postgres.Berkeley.EDU>
From: postarch (Postgres Mailing Archive)
Subject: Re: locking provisions?
To: postgres@postgres.berkeley.edu
Sender: pg_adm@postgres.berkeley.edu
In-Reply-To: Your message of "Mon, 18 Nov 91 12:33:27 PST."
             <9111182033.AA09126@postgres.Berkeley.EDU> 
Date: Mon, 18 Nov 91 13:33:18 PST

In message <9111182033.AA09126@postgres.Berkeley.EDU> you write:
> 
> Are there any locking provisions in the current postgres release?
> If so, what's the granularity? 

Yes, POSTGRES keeps a multi-level lock table for its databases and
provides two-phase locking on all user classes and non-two-phase
locking on system catalogs.  The granularity depends on what
you are doing.  Index creation and scans set page level locks while 
sequential scans (this currently includes catalog accesses) set only
relation level locks.  We currently do no tuple level locking at all.


Jeff Meredith
mer@postgres.berkeley.edu