Dynamic Collisions

A dynamic collision occurs when a schema change is committed on a table, procedure, function, or view while a secondary server is querying the same object. The collision results from the TLV replay of shared IQ object schema updates.

Dynamic collisions only occur on secondary nodes. In an interactive setting, a dynamic collision results in a forced disconnect of a user connection from a secondary node.

To resolve a dynamic collision during DDL execution, the secondary server finds the connections responsible and disconnects them. The disconnect is logged in the .iqmsg file with a message similar to:

Shared IQ Store update DDL statement:
drop table DBA.gtt44
Disposition: SQLSTATE:42W21 --
dropped 1 connection(s) for table:
DBA.gtt44 Retry successful

To avoid dynamic collisions, schedule schema changes when the multiplex is not heavily loaded.