A fix is available
APAR status
Closed as program error.
Error description
Inefficient access path for query with function MIN or MAX by incorrect reduction for early out
Local fix
OPTHINT
Problem summary
**************************************************************** * USERS AFFECTED: All DB2 11 for z/OS users that have a query * * having join with function MAX or MIN. * **************************************************************** * PROBLEM DESCRIPTION: DB2 may select an inefficient access * * path for a query having join with * * function MAX or MIN. * **************************************************************** * RECOMMENDATION: * **************************************************************** The problem here is that DB2 underestimates the cost of the access path which could provide the order for column in the function MAX or MIN, and the query contains a join. Due to the incorrect costing of the access path, DB2 may select an inefficient access path. Here is an example query: SELECT MIN ( T1.C1 ) FROM T1, T2 WHERE T1.C2 = T2.C2 AND T2.C1 = ?; There is an index IX1(C1) on table T1. DB2 may underestimate the cost of the access path which uses join sequence T1 to T2, and T1 uses index IX1 which could provide the order for T1.C1. Additional Keywords: SQLACCESSPATH SQLMAX SQLMIN
Problem conclusion
DB2 corrects the problem where it underestimates the cost of a query with MAX or MIN.
Temporary fix
Comments
APAR Information
APAR number
PI49557
Reported component name
DB2 OS/390 & Z/
Reported component ID
5740XYR00
Reported release
B10
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2015-09-30
Closed date
2015-12-02
Last modified date
2016-01-04
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI33463
Modules/Macros
DSNXOPNR
Fix information
Fixed component name
DB2 OS/390 & Z/
Fixed component ID
5740XYR00
Applicable component levels
RB10 PSY UI33463
UP15/12/19 P F512
Fix is available
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Document Information
Modified date:
04 January 2016