resynchronizing mnesia nodes

[Chandrashekhar Mullaparthi]

I think when such a thing happens, you can set the master nodes for each
table so that when the nodes resync, one of the tables is considered the
"correct" one. But I don't think it is possible to merge tables - I'm not
sure that it is even desirable. But if it is - then mnesia could invoke a
user defined merge fun which would take in as parameters each conflict entry
and return a result such as {ok, NewEntry} or discard. For large tables -
this can mean that mnesia will take a long time to resync.

cheers,
Chandru

-----Original Message-----
From: Hal Snyder [mailto:hal@REDACTED]
Sent: 10 April 2002 15:06
To: erlang-questions@REDACTED
Subject: resynchronizing mnesia nodes


We are looking at various policies for recovering from communication
failure with mnesia, and studying Chapter 6 of the Mnesia User's
Guide, Version 4.0.

Suppose you have several nodes running mnesia, replicating content.
They become partitioned long enough to record mutual mnesia_down
entries, and continue to receive updates.
 
In some special cases - for example, when updates to a table consist
only of adding a positive increment to a counter, or of inserting a
record with a globally unique key - it should be possible to
resynchronize automatically without fear of inconsistencies.
 
Is this sort of thing readily feasible with mnesia?
Is anyone doing it?



NOTICE AND DISCLAIMER:
This email (including attachments) is confidential.  If you have received
this email in error please notify the sender immediately and delete this
email from your system without copying or disseminating it or placing any
reliance upon its contents.  We cannot accept liability for any breaches of
confidence arising through use of email.  Any opinions expressed in this
email (including attachments) are those of the author and do not necessarily
reflect our opinions.  We will not accept responsibility for any commitments
made by our employees outside the scope of our business.  We do not warrant
the accuracy or completeness of such information.