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Problem IC95347
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Status: Closed |
COLLECTING INDEX-ONLY STATISTICS CAN INCORRECTLY UPDATE SYSCAT.COLUMNS.NQUANTILES AND SYSCAT.COLUMNS.NMOSTFREQ TO -1. |
| product: |
DB2 FOR LUW / DB2FORLUW / A50 - DB2 |
| Problem description: |
If a column has distribution statistics and it is the leading
column in an index, collecting index-only statistics for the
index will incorrectly update SYSCAT.COLUMNS.NQUANTILES and
SYSCAT.COLUMNS.NMOSTFREQ to -1, suggesting the column does not
have distribution statistics. However, the column's
distribution statistics are not affected in the
SYSCAT.SYSCOLDIST catalog. Also not affected are the
distribution statistics in the table's packed descriptor which
is used by the query optimizer.
The problem therefore affects applications that query
SYSCAT.COLUMNS.NQUANTILES and SYSCAT.COLUMNS.NMOSTFREQ, instead
of SYSCAT.SYSCOLDIST, to determine if a column has distribution
statistics. The db2look tool is affected by this problem. When
the problem has occurred, db2look mimic output will not contain
distribution statistics information for the affected columns. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* ALL *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to DB2 v10.5 FP3 *
**************************************************************** |
| Local Fix: |
Perform a table and indexes statistics collection on the
affected tables. |
| Solution |
Problem Fixed In DB2 v10.5 FP3 |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 27.08.2013
21.04.2014
21.04.2014 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
