To skip unneeded statistics recollections, specify the THRESHOLD option of the COLLECT STATISTICS request. With this option, if the amount of data that changed since the last statistics collection is below a specified threshold or the statistics are newer than a specified age, Teradata does not recollect statistics.
You can issue COLLECT STATISTICS requests at regular intervals without being concerned that you may be wasting I/O and CPU by collecting statistics too soon. Teradata skips the recollections for the statistics whose thresholds are not met and recollects the statistics for those columns that are over the threshold. For example, if the threshold is 10% data change and you request a recollection, Teradata skips recollection if less than 10% of the data changed since the last collection.
If you specify the THRESHOLD option the first time you collect statistics, Teradata collects the statistics and remembers the THRESHOLD option. When you recollect statistics, Teradata uses the saved threshold to determine whether statistics recollection is needed. To tell Teradata to ignore the THRESHOLD option (without resetting the option), use the FOR CURRENT option after the percent specification.
You can query the LastCollectTimeStamp column of the Data Dictionary table DBC.StatsTbl to see whether data is collected or not.
The user-specified change threshold percent is not supported for statistics on views and queries.
For the syntax of the COLLECT STATISTICS statement, see COLLECT STATISTICS (Optimizer Form).