At 09:50 AM 01-08-02 +0200, you wrote:

>Hello
>
>I want to set up two (or more) database server machines redundantly,
>supporting a "failover" scenario where a "standby" machine takes over
>operation from the "lead" machine as soon as the "lead" dies. This can be
>done for example with "HA Linux" (www.linux-ha.org).
>
>Now the obvious problem with the database is that I need to keep current a
>data file on the standby, i. e., somehow send all updates done to the "lead"
>database also to the standby database.

Have you investigated the database shadowing capability?

>It would also sufficient to have a current .gbk file on the standby, and only
>restore it to a .gdb in the failover case. But, of course, I want to avoid
>sending the whole data file (or a backup) to the standby periodically. I'm
>looking for a solution that just only sends the updates.

Firebird/InterBase doesn't support incremental backups so this isn't an option.

>For example, it would be useful if a UDF could be passed the full SQL insert,
>update, or delete commands, triggered whenever one of these is issued. Such a
>UDF could just connect to the standby machine and apply the same command
>there.

Erm, not really. UDFs are used for massaging values. UDFs can't connect
to databases or behave like database clients.

If shadowing can't provide the coverage you need then what you
are probably looking at is some kind of replication solution involving
triggers that fire when a DML operation occurs and use the event mechanism
to signal a server-based application to update tables on the "foreign" server..

cheers
heLen

All for Open and Open for All
Firebird Open SQL Database · http://firebirdsql.org ·
http://users.tpg.com.au/helebor/
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