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UPDATE STATISTICS


Updates the statistics recorded for all tables in the database, a specified list of tables or all the tables belonging to the schemas owned by a specified list of idents.



Usage

Embedded/Interactive/ODBC/JDBC.

Description

The default operation is to update statistics for all tables, including data dictionary tables, in the database.

It is possible to update statistics for a specified list of tables by using the FOR TABLE option or for all the tables belonging to the schemas created by a specified list of idents by using the FOR IDENT option.

Update statistics includes an automatic operation which ensures the consistency of secondary indexes (both explicitly created indexes and those created by the system when certain constraints are defined). The operation is transparent to users of the database and is performed on indexes selected by the UPDATE STATISTICS statement that are contained in a databank with the TRANSACTION or LOG option and which are flagged as `not consistent'.

The process of ensuring the consistency of an index, and updating statistics for all tables in the database (the default operation), can be rather time-consuming. Therefore, it is generally recommended that these operations be performed in batch mode and at off-peak times, refer to the Mimer SQL System Management Handbook, Database Statistics for more information.

A secondary index is flagged as not consistent if it is contained in a databank with the WORK option or if the databank containing it has been upgraded from Mimer SQL version 8.1 (or older).

The IS_CONSISTENT column in the data dictionary table TABLE_CONSTRAINTS shows which indexes in the database are flagged as not consistent.

Restrictions

The current ident must be the creator of all the tables involved or must have STATISTICS privilege.

Notes

The UPDATE STATISTICS statement can be used concurrently with other SQL statements.

Precompiled statements may change search orders depending on the result of the updated statistics.

Example

 UPDATE STATISTICS FOR IDENT joe;
 

For more information, see the Mimer SQL System Management Handbook, Database Statistics.

Standard Compliance

Standard
Compliance
Comments

Mimer SQL extension
The UPDATE STATISTICS statement is a Mimer SQL extension.


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