How to collect expression stats

With 14.10, we can now collect stats on single table expressions. This improves estimations of the query with expressions; stats can be collected as they were with columns:

COLLECT [SUMMARY] STATISTICS
[USING options]
COLUMN expr [[AS] statistics_name]
[,COLUMN (expr […, expr]) [[AS] statistics_name]]
ON [TEMPORARY] <Table>;

One of the mandatory requirements of the expression stats is that they need to be named. This name, which follows the same rules as other naming database objects, can be used to recollect, help, show, or drop the statistics.

Getting ready

To collect statistics, you need to connect to the Teradata database using Teradata studio or SQLA.

Identify the expression on which statistics need to be collected.

How to do it...

1. Identify the query on which expression stats need to be collected.
2. Use the following format to collect statistics:

COLLECT [SUMMARY] STATISTICS
[USING options]
COLUMN expr [[AS] statistics_name]
[,COLUMN (expr […, expr]) [[AS...