What is Update Statistics in Informix?
The UPDATE STATISTICS statement converts the old indexes to conform to the newer database server index format and implicitly drops the old indexes. You can convert the indexes table by table or for the entire database at one time. Follow the conversion guidelines in the IBM® Informix® Migration Guide .
How do you update DB statistics?
To update a statistics object
- In Object Explorer, click the plus sign to expand the database in which you want to update the statistic.
- Click the plus sign to expand the Tables folder.
- Click the plus sign to expand the table in which you want to update the statistic.
- Click the plus sign to expand the Statistics folder.
What is update stats?
sp_updatestats will update the statistics for every user defined table in the database it is run against. The UPDATE STATISTICS command gives you the ability to use the same sampling options that were outlined above with the CREATE STATISTICS command.
When should I run update statistics?
Answer. For good database performance with a cost-based optimizer, run the update statistics procedure at least once a week. Run the two step procedure for update statistics on the most important DB2® tables.
Does update statistics cause blocking?
We all know that both operations, an index reorganization and update statistics in SQL Server, will not block normal DML statements on their own. (i.e. ANY SELECT, INSERT, UPDATE or DELETE).
How to convert old indexes to new indexes in Informix?
The UPDATE STATISTICS statement converts the old indexes to conform to the newer database server index format and implicitly drops the old indexes. You can choose to convert the indexes table by table or for the entire database at one time. Follow the conversion guidelines in the Informix Migration Guide.
How to update the statistics for a table in a 4GL?
After adding or deleting many rows in a 4GL program, use the statement “UPDATE STATISTICS FOR table_name” to update the information the optimizer uses. 11. Plan your locking method Row locking allows many people to update data at the same time.
How to optimize query optimization in Informix?
The Informix 12.10 manual suggests: Using the MEDIUM mode option After UPDATE STATISTICS MEDIUM has been run on a table, the query optimizer typically chooses a more efficient execution plan, compared to the same SELECT statement when only LOW mode column distribution statistics are available for the table. column. Using the HIGH mode option:
What are the most common problems with Informix?
1 Informix – deadlock scenario involving single table 1 Informix DELETE query taking long time 2 Why do I get this error when inserting a record: duplicate value for a record with unique key 0 Informix Database table update 1 Does some tables in Informix take values of a column only in lower case?