benefits of multiple switch logfile calls?

From: Don Seiler <don_at_seiler.us>
Date: Wed, 03 Dec 2003 19:07:43 GMT
Message-ID: <pan.2003.12.03.19.10.01.379872@seiler.us>

Testing hot backup strategy for Oracle 9.2.0.4. Due to space concerns I'm not using RMAN right now, just putting tablespaces in backup mode and gzipping datafiles to backup dir, similar to what we do now in Oracle 7.3.4.5.

One problem I have is that my test recover failed complaining that it needed to apply more archive logs. The logfile it asks for was not created. In my new backup script I call "ALTER DATABASE ARCHIVE LOG CURRENT" before copying over the log files.

However in the Oracle 7.3.4.5 (written by wiser consultant 5 years before my time) script, there are three "switch logfile" statements in succession followed by the archive log current, literally like this:

  ALTER SYSTEM SWITCH LOGFILE;
  ALTER SYSTEM SWITCH LOGFILE;
  ALTER SYSTEM SWITCH LOGFILE;

  ALTER SYSTEM ARCHIVE LOG CURRENT; Would that fact that I'm not calling SWITCH LOGFILE at all (let alone multiple times) lead to the fact that I'm missing some redo info? I don't understand why multiple calls are of any value, but I've seen it done in other scripts on the web and in the Oracle news groups. Received on Wed Dec 03 2003 - 13:07:43 CST