IQ Multiplex: How to programmatically detect if secondary nodes need to be resynced

[Former Member]

Hi all,

The IQ manual says:

In general, Sybase IQ propagates DDL and DML changes to secondary servers, so you only need to synchronize a secondary server for these server management actions:

While creating a new secondary server

Restoring the coordinator from backup

Restarting a secondary server that has been excluded or shut down for an extended time period

After running the coordinator in single-node mode

After adding a file to the IQ_SYSTEM_MAIN dbspace

In practice, on IQ 16.0 SP8 PL30, I've been finding any along with the above any changes involving logical servers and alter multiplex server... cause the current_version in SYS.SYSIQMPXSERVER to be incremented on the coordinator node and not for the secondary nodes.  That's fine, are there any other things that could cause the secondary nodes to be out of sync with the coordinator?

I'm trying to identify what could cause the secondary nodes to become out of sync and determine how urgent the secondary nodes need to be sync'd for each cause.  For example, if I add a logical server, does it matter for a secondary node to be synchronized if that secondary node isn't part of the logical server?

Along those lines, is there any way on determining within IQ which item caused the secondary nodes to become out of sync or do I need to take periodic snapshots of the appropriate system views to compare (before/after)?  One troublesome scenario:  a logical server is defined on the wrong IQ cluster and is promptly dropped, the current_versions are now out of sync but the snapshots may not have been able to capture such a change.

thoughts?

Jason

[markmumy · Accepted solution]

Jason,

When a node needs to be synced it will shut down or will refuse to start. Other than that, there should be no need to resync a node. All situations above will prevent a node from starting until the resync is done.

Are your nodes getting out of sync and shitting down?  Outside of that I can't imagine why you would want to sync a node.

Mark

[Former Member · Accepted solution]

thanks Mark!  That's what I thought