Subject: Re: Does a the block of code within a stored procedure constitute
From: Rod Taylor <rbt@rbt.ca>
To: btober@seaworthysys.com
Cc: pgsql-sql@postgresql.org
In-Reply-To: <64821.216.238.112.88.1059509762.squirrel@$HOSTNAME>
References: <64821.216.238.112.88.1059509762.squirrel@$HOSTNAME>
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Date: 31 Jul 2003 20:37:18 -0400

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> What I need to know is whether or not this is multi-user safe, i.e., will
> the block of code in the procedure execute as a transaction so that if
> more than one clerk creates an expense report for the same employee
> simultaneously is it possible or impossible that value of the
> employee.expense_report_seq gets updated by the second clerk between the
> SELECT and UPDATE statements invoked by the first clerk?
>=20
> And as a follow-up, should I add the FOR UPDATE clause to the SELECT
> statement?

SELECT .. FOR UPDATE would be appropriate.

However, you could also do an update + 1 first and the select second to
find what you changed the value to.

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