In IDS 9.2.1 and later, the database server uses the SQL statement cache (SSC) to store SQL statements across user sessions. When any user executes a statement already stored in the SQL statement cache, the database server does not parse and optimize the statement again, resulting in improved performance. The statement must be a SELECT, UPDATE, DELETE, or INSERT statement, and it cannot contain user-defined routines.
There are several ways to configure caching on the server. The SET STATEMENT CACHE statement takes precedence over the STMT_CACHE environment variable and the STMT_CACHE configuration parameter. You must enable the SQL statement cache, either by setting the STMT_CACHE configuration parameter or by using the Informix onmode utility, before the SET STATEMENT CACHE statement can execute successfully.
You can set the StmtCache DBParm on the System tab page in the Database Profile Setup dialog box for I10 connections to turn SQL statement caching on or off on the client. However, the server must be configured to support SQL statement caching before you can access the cache from the client.
For more information about Informix SQL statement caching, see the IBM Informix Dynamic Server Performance Guide.
