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sybperl-l Archive

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From: Michael Peppler <mpeppler at MBAY dot NET>
Subject: Re: Locking Databases
Date: Dec 4 1997 4:03PM

Kevin Stussman wrote:
> 
> We are using a HR/Benefits package (many table, many database, many
> interdependencies) that requires "select into / bulk copy" and "trunc
> log on checkpoint" on all the time (don't get me started on the whys of
> this...rrrrrgh)
> 
> I'm using Datatools "SQL Backtrack for Sybase" to do backups, but am
> concerned that the backups will not have a consistent snapshot of the
> databases (i.e. user updates might occur in between backups on
> interdependent databases). The only solution I can think of is to write
> a sybperl script that will put all the databases (except master and
> tempdb) into read-only mode while the backups occur.

The problem is that you can't put the databases in read-only mode
if users are using them (ie if some user has done a 'use database'
for the database that you want to set to read-only).

The other option is to set the database to single user mode, but
for that you also need to make sure that no users are connected to
the databases.

If *no* clients execute any dbuse() or 'use database' commands then
it might be possible to set the databases to read-only, but you're
going to have to test the error messages and failure modes thoroughly
because I don't know what happens if you try to set a database to 
read-only when someone is running an update...

Michael
-- 
Michael Peppler       -||-  Data Migrations Inc.
mpeppler@datamig.com  -||-  http://www.mbay.net/~mpeppler