Statistics support (not available for C++ or Java)

Statistics support is available with HCL Informix® Version 9.2 and later.

This category is valid for the C language.

User-defined statistics provide a way to improve performance when you compare opaque data type values. User-defined statistics compile information about the values in an opaque data type column that the query optimizer can use when it creates a query plan.

You can define statistics support functions for an opaque data type and then a selectivity function for a routine that takes opaque data types as its arguments.

Statistics support functions are OpaqueStatCollect(), OpaqueStatPrint(), Opaque_SetMinValue(), Opaque_SetMaxValue(), and Opaque_SetHistogram().
Tip: Statistics support functions are in the statistics.c source code file, instead of in the opaque.c source code file with all other opaque data type support routines.