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RE: InstantDB: Date: Mon, 11 Dec 2000 13:44:09 +0100


Title:
Accessing your InstantDb from 2 JVM's at the same time causes this problem. E.g. looking at the DB under the example browser provided and also from an application. I make this mistake occasionally.
 
Setting  recoveryPolicy=2 in the .prp file can be used to stop multiple JVM's accessing the DB. A recoveryPolicy=1 allows for automatic recovery and as a side effect seems to allow more than one JVM. This seems a bit odd really.

If you have recoveryPolicy=2 and then you try and access from 2 JVM's I believe you will get the message you are seeing below. Basically the DB thinks/knows it is being accessed by another JVM and assumes that if another JVM tries to attach that the DB must be in an inconsistent state from a previous execution.

If the DB has not closed down correctly on a previous occasion I would expect to see a similar problem. To avoid the message set recoveryPolicy=1, the side effect of this is that multiple JVM's will really be allowed to open the DB increasing the risk of real corruption.

Hope this is helpful. Peter Hearty may tell me that some of this is incorrect. But it what I believe is happening, without having seen the code.

John.
-----Original Message-----
From: owner-instantDB@enhydra.org [mailto:owner-instantDB@enhydra.org]On Behalf Of Haans, Jaco
Sent: 11 December 2000 13:48
To: instantDB@enhydra.org
Subject: InstantDB: Date: Mon, 11 Dec 2000 13:44:09 +0100


Hi all,

Can anyone help me on this one. I got the following message during statup of the application:

Enhydra InstantDB - Version 3.14
The Initial Developer of the Original Code is Lutris Technologies Inc.
Portions created by Lutris are Copyright (C) 1997-2000 Lutris Technologies, Inc.
All Rights Reserved.
WARNING!!! - THE DATABASE JOURNAL FILE IS CORRUPT.
SOME DATA MAY BE IN AN INCONSISTENT STATE.


My questions are:

- What could be the cause of a corrupt database journal file?
- What is the effect of this corrupt file?
- Is this a fatal fault? Is the database lost?
- How to prevent this (besides recoveryPolicy)?

Thanks in advance.
Jaco