mi_integer am_stats(MI_AM_TABLE_DESC *tableDesc,
   MI_AM_TSTATS_DESC *tstatsDesc);

tableDesc

points to the table descriptor.

tstatsDesc

points to the statistics descriptor.

To influence the am_stats sampling rate, an UPDATE STATISTICS statement might include an optional distribution-level keyword, low, medium, or high. If the UPDATE STISTISTICS statement does not include one of these keywords, the default low distribution level applies.

Adjust the sampling rate in your version of the am_stats purpose function according to the distribution-level keyword that the user specifies in the UPDATE STATISTICS statement. To determine which keyword—LOW, MEDIUM, or HIGH—an UPDATE STATISTICS statement specifies, call the mi_tab_update_stat_mode() function. For detailed information about the sampling rates that each keyword implies, refer to the description of UPDATE STATISTICS in the IBM Informix: Guide to SQL Syntax.

The am_stats purpose function calls the various VTI accessor functions that set values in the statistics descriptor for the database server. The database server places the statistics descriptor results in the systables and syscolumns, system catalog tables. The am_stats function can also save any additional values in a location that am_scancost can access, such as a file in the extspace or a table in sbspace.

MI_OK indicates success. MI_ERROR indicates failure.

See the descriptions of:

• The am_scancost purpose function
• Accessor functions mi_tab_update_stat_mode() and mi_tstats_* in Descriptor Function Reference
• The Descriptor Function Reference
• Updating Statistics