APAR status
Closed as program error.
Error description
You create a view that is a UNION ALL of two tables. You execute a SELECT COUNT(*) on the view. You compare the execution time with a SELECT COUNT(*) on a UNION ALL of the same tables and it executes much faster. The query plans show that the view query uses sequential scans and creates a temporary table. The select on the table unions uses index access and does not create a temporary table.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: * * All 11.50 users. * **************************************************************** * PROBLEM DESCRIPTION: * * A simple query containing aggregation on a simple UNION ALL * * view (without group by, order by, distinct, aggregation, * * etc) experiences performance issues due to materialization * * of UNION ALL view before performing the aggregation. * **************************************************************** * RECOMMENDATION: * * Upgrade to 11.50.xC9. * ****************************************************************
Problem conclusion
The issue is fixed in 11.50.xC9, in case the main query only contains a single table (which is the UNION ALL view), and the main query is otherwise simple (no group by, order by, distinct). In this case the aggregation can be evaluated within each arm of the UNION ALL view, and then the partial aggregates can be aggregated together. This functionality requires the onconfig variable IFX_FOLDVIEW to be on.
Temporary fix
Comments
APAR Information
APAR number
IC74702
Reported component name
IBM IDS ENTRP E
Reported component ID
5724L2304
Reported release
B15
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2011-02-25
Closed date
2011-09-27
Last modified date
2011-09-27
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
Fix information
Fixed component name
IBM IDS ENTRP E
Fixed component ID
5724L2304
Applicable component levels
RB15 PSN
UP
[{"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSGU8G","label":"Informix Servers"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"B15","Edition":"","Line of Business":{"code":"LOB10","label":"Data and AI"}}]
Document Information
Modified date:
27 September 2011