Restrictions on optimized message transfers

Informix® ESQL/C does not chain the following SQL statements even when you enable optimized message transfers:
  • COMMIT WORK
  • DESCRIBE
  • EXECUTE
  • FETCH
  • FLUSH
  • PREPARE
  • PUT
  • ROLLBACK WORK
  • SELECT INTO (singleton SELECT)

When Informix® ESQL/C reaches one of the preceding statements, it flushes the message out to the database server. Informix® ESQL/C then continues message chaining for subsequent SQL statements. Only SQL statements that require network traffic cause Informix® ESQL/C to flush the message queue.

SQL statements that do not require network traffic, such as the DECLARE statement, do not cause Informix® ESQL/C to send the message queue to the database server.