DB2 FOR LUW / DB2FORLUW / B10 - DB2

Starting with Db2 server 11.1, queries with predicates of the
form ROWID=? or RID_BIT()=? may perform slowly when
DB2_DEFERRED_PREPARE_SEMANTICS=YES.  The problem can be seen in
the explain plan, where the slow query shows a TBSCAN over the
base table:

       40
     TBSCAN
     (   2)
     160.278
        5
       |
      1000
TABLE: MYSCHEMA
        T
       Q1

A good query will show a FETCH over the base table:

        1
     FETCH
     (   2)
     0.0364
        0
       |
      1000
TABLE: MYSCHEMA
        T
       Q1

****************************************************************
* USERS AFFECTED:                                              *
* ALL                                                          *
****************************************************************
* PROBLEM DESCRIPTION:                                         *
* See Error Description                                        *
****************************************************************
* RECOMMENDATION:                                              *
* See Local Fix                                                *
****************************************************************

The problem can be avoided with any of the following three
methods:

1. Set DB2_DEFERRED_PREPARE_SEMANTICS=NO
2. Change the SQL statement to explicitly cast the parameter
marker as follows:

    ... WHERE ROWID=CAST(? as VARCHAR(16) FOR BIT DATA)

3. In the application, explicitly assign a data type of VARCHAR
to the parameter marker.  For example, in a JDBC application,
instead of
    PreparedStatement.setBytes(n,bytearray)
use

PreparedStatement.setObject(n,bytearray,java.sql.Types.VARCHAR)
    For this workaround, jcc property sendDataAsIs should be
false(default value).

****************************************************************
* USERS AFFECTED:                                              *
* ALL                                                          *
****************************************************************
* PROBLEM DESCRIPTION:                                         *
* See Error Description                                        *
****************************************************************
* RECOMMENDATION:                                              *
* See Local Fix                                                *
****************************************************************

Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :

27.02.2020
02.12.2021
02.12.2021