|
Problem IT34308
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Status: Closed |
REPLICATED MQT MATCH MAY FAIL IN SOME SPECIFIC SITUATIONS
|
| product: |
DB2 FOR LUW / DB2FORLUW / B50 - DB2 |
| Problem description: |
Replicated MQT match may fail when following conditions are met:
- MQT's base table is joined with other table and nullability
differs between columns on both sides of the join.
- MQT's base table is referenced more than once in the query
The source of the problem is a join predicate:
ON mqtbt.a_id = t1.a_id AND
Where:
- mqtbt - MQT's base table
- mqtbt.a_id is a nullable column and t1.a_id is non-nullable
column.
As a result of internal query rewrite, mqtbt.a_id becomes not
nullable, but the same is not true for compensation built for
MQT matching purpose.
That difference in nullability prevents MQT match. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* all *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Db2 11.5.5.0 or higher *
**************************************************************** |
| Local Fix: |
A potential workaround could be to ensure that mqtbt.a_id and
mqtbt.a_id do not differ in terms of nullability - make both
columns nullable or both not-nullable. For columnar tables it
would require table drop and recreation |
| Solution |
|
| Workaround |
****************************************************************
* USERS AFFECTED: *
* all *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Db2 11.5.5.0 or higher *
**************************************************************** |
| Comment |
Upgrade to Db2 11.5.5.0 or higher |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 22.09.2020
20.11.2020
20.11.2020 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
