DB2 - Problem description
Problem IT04888 | Status: Closed |
OPTIMIZER MIGHT PRODUCE NON-OPTIMAL ACCESS PLAN IN DPF FOR QUERIES WITH MULTIPLE LOCAL EQUALITY PREDICATES | |
product: | |
DB2 FOR LUW / DB2FORLUW / A10 - DB2 | |
Problem description: | |
The DB2 optimizer might produce a non-optimal access plan, in a DPF environment, for SQL statements under the following conditions: 1. The SQL statement includes two or more local equality predicates applied to a table distributed across multiple database partitions 2. The local equality predicates reference literal values, including variable values when REOPT is enabled, that are infrequent or don't exist 3. There is a column group statistic or index that covers the local equality predicates Under these conditions, the optimizer will correctly estimate the individual filter factors of the local equality predicates, but it will use the index or column group statistics to account for statistical correlation. In doing so, the optimizer might over-estimate the cardinality which could lead to a non-optimal access plan being chosen. | |
Problem Summary: | |
**************************************************************** * USERS AFFECTED: * * ALL * **************************************************************** * PROBLEM DESCRIPTION: * * See Error Description * **************************************************************** * RECOMMENDATION: * * UPGRADE TO DB2 V10.1 FP5 * **************************************************************** | |
Local Fix: | |
Solution | |
FIRST FIXED IN DB2 V10.1 FP5 | |
Workaround | |
not known / see Local fix | |
Timestamps | |
Date - problem reported : Date - problem closed : Date - last modified : | 13.10.2014 12.08.2015 12.08.2015 |
Problem solved at the following versions (IBM BugInfos) | |
Problem solved according to the fixlist(s) of the following version(s) | |
10.1.0.5 |