Heterogeneous commit protocol

Used in the context of HCL Informix® database servers, the term heterogeneous environment is a group of database servers in which at least one of the database servers is a different database server. Heterogeneous commit ensures the all-or-nothing basis of distributed transactions in a heterogeneous environment.

Unlike the two-phase commit protocol, the heterogeneous commit protocol supports the participation of a participant that is not Informix. The other participant, called a gateway participant, must communicate with the coordinator through the HCL Informix gateway.

The database server uses heterogeneous commit protocol when the following criteria are met:

• Heterogeneous commit is enabled. (That is, the HETERO_COMMIT configuration parameter is set to 1.)
• The coordinator of the commit is a version 7.2 or later HCL Informix.
• The gateway participant communicates with the HCL Informix database server through the HCL Informix gateway.
• At most, one gateway participant performs an update within a single transaction.

The following figure illustrates this scenario.

Figure 1. Configuration that requires heterogeneous commit for distributed transactions