New in v2.1: Use the CREATE STATISTICS statement to generate table statistics for the cost-based optimizer to use.
Once you create a table and load data into it (e.g., INSERT, IMPORT), table statistics can be generated. Table statistics help the cost-based optimizer determine the cardinality of the rows used in each query, which helps to predict more accurate costs.
This is an experimental feature. The interface and output are subject to change.
Considerations
Each time CREATE STATISTICS is used, a new statistic is created without removing any old statistics. To delete statistics for all tables in all databases, use DELETE.
Synopsis
Required Privileges
The user must have the CREATE privilege on the parent database.
Parameters
| Parameter | Description |
|---|---|
statistics_name |
The name of the statistic you are creating. |
column_name |
The name of the column you want to create the statistic for. |
table_name |
The name of the table you want to create the statistic for. |
Examples
Create statistics
> CREATE STATISTICS students ON id FROM students_by_list;
CREATE STATISTICS
Multi-column statistics are not supported yet.
Delete all statistics
To delete statistics for all tables in all databases:
> DELETE FROM system.table_statistics WHERE true;
DELETE 1
For more information, see DELETE.
See Also
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