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To: Daniel Roth <dan.c.roth@gmail.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: predicate locking 
In-reply-to: <71038fca0506121916764f5b33@mail.gmail.com> 
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	<23768.1118588642@sss.pgh.pa.us>
	<71038fca0506121916764f5b33@mail.gmail.com>
Comments: In-reply-to Daniel Roth <dan.c.roth@gmail.com>
	message dated "Mon, 13 Jun 2005 10:16:44 +0800"
Date: Sun, 12 Jun 2005 23:04:29 -0400
Message-ID: <10450.1118631869@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
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Daniel Roth <dan.c.roth@gmail.com> writes:
> It sates: "To guarantee true mathematical serializability, it is
> necessary for a database system to enforce predicate locking, which
> means that a transaction cannot insert or modify a row that would have
> matched the WHERE condition of a query in another concurrent
> transaction"

> Now that is exactly whats happens when you use SERIALIZABLE is MSSQL.

Only for WHERE conditions that can be expressed as a simple range
constraint.

> All I am trying to do is correct the help documentation - 12.2.2.1 "so
> far as we are aware no other production DBMS does either."

The documentation is not wrong; or at least, what you've quoted does not
show that it is.

			regards, tom lane