As you must have noticed, we'll rescan and recollect statistics only
if there is sufficient UDI (update, delete, insert) activity on the fragment.
This aspect of monitoring the UDI activity works not just for
fragmented(partitioned) tables, but for all tables in Informix v11.70.
By default, when you run update statistics, we recollect the statistics at if and only if
10% of the rows have been modified since the the last run. With v11.70, kernel maintains
these counters and update statistics command retrieves and uses it dynamically.
This is the default behavior for all LOW/MEDIUM/HIGH modes.
This check is done at table, fragment, index (fragmented or otherwise) level.
You can force the refresh of all stats by using the FORCE modifier to UPDATE STATISTICS command.
onconfig variables AUTO_STAT_MODE and STATCHANGE control this behavior.
You can also control this at session level via SET ENVIRONMENT AUTO_STAT_MODE
and STATCHANGE settings and at table level via ALTER TABLE statistics clauses.
This is conceptually simple, but powerful feature in Informix v11.70.
This in conjunction with fragment(partition) level statistics,
makes Update statistics sense what's required to recollect and
do incremental changes to global statistics quickly.
Your update statistics scripts should already be running faster on v11.70.
Just in case, may the FORCE be with you, but use it sparingly.
***Informix v11.70 manuals are at http://publib.boulder.ibm.com/infocenter/idshelp/v117/index.jsp