You update the statistics for the SQL Optimizer.
The database instance is in the ONLINE operational state.
Select the required database instance in the list of database instances. Choose Instance ® Tuning ® Optimizer Statistics.
The database system contains an internal list of the tables whose statistics need to be updated.
·
Updating
statistics entries for all tables
You can update the statistics entries for all tables in this internal list. To
do so, do not enter a search argument under Search; instead, just enter *.
Updating statistics entries for selected tables
You can update the statistics entries for selected tables in this internal
list. To do so, enter appropriate search arguments for the owner, table name,
and column name under Search.
Owner |
Owner |
Table Name |
Name of the table |
Column Name |
Name of the column |
· You can determine the size of a sample. To do so, enter appropriate information under Estimate.
Use estimate value |
Select this option. |
Percent |
Percentage of rows to be checked |
The update is only performed across the specified percentage, based on the total number of database tables. This option, therefore, is faster.
The significance of the random sample depends on the size of the tables and the physical position of the data. Measurements have shown that for large tables (more than 1 million entries), samples of more than 20000 rows produce good results.
· Independently of the internal list, you can display all tables for which statistics can be updated. To do so, choose Select from tablesunder Advanced.
...
1. Choose Actions ® Search.
2.
A list of the
tables is displayed that matches your criteria under Search or Advanced. From the Update Statistics
Dateand Update Statistics
Time, you can tell when
the statistics for this table were last updated.
If you want to update the statistics for one of the tables in the list,
simply select the relevant entry. If you want to update the statistics for
all the tables, choose Actions ® Mark All.
Select Include update columns for marked
tables (under
Advanced) if you want to update column statistics as well as
the table statistics. You can display the columns of a table by double
clicking. Select the required columns.
3.
Choose Actions
® Execute to update the statistics for the selected
tables.
If you have not selected any tables, the statistics of those tables are
updated that are in the internal list of the database system.