DROP_STATISTICS

Removes statistical data on database projections previously generated by ANALYZE_STATISTICS. When you drop this data, the Vertica optimizer uses default statistics to create query plans.

Caution: Before you drop statistics, be aware that statistics can be time consuming to regenerate.

Syntax

DROP_STATISTICS ('[ scope ]'[, 'category'] [, 'column[,…]' )

Parameters

scope

Specifies the target table as follows:

[[database.]schema.]table

If set to an empty string, Vertica drops statistics for projections of all database tables.

If you specify a database, it must be the current database.
category

The category of statistics to drop for the named table, one of the following:

  • BASE (default) drops histograms and row counts (min/max column values, histogram).
  • HISTOGRAMS drops only histograms. Row counts statistics remain.
  • ALL drops all statistics.
column

The name of a column in table, typically a predicate column. You can specify multiple comma-delimited columns. Vertica narrows the scope of dropped statistics to the specified columns only.

Privileges

Examples

Drop all base statistics for the table store.store_sales_fact:

=> SELECT DROP_STATISTICS('store.store_sales_fact'); 
 DROP_STATISTICS
-----------------
               0
(1 row)

Drop statistics for all table projections:

=> SELECT DROP_STATISTICS (''); 
 DROP_STATISTICS
-----------------
               0
(1 row)

See Also