The SETURLKEY function provides an alternative to the default Topic partitioning options provided by the Kafka DATASTORE url.
Important: The
SETURLKEY with correctly provided URL specification
is compatible with the KEY IS clause which appears on a DESCRIPTION or
target DATASTORE statement. Keys formed by SETURLKEY do not contain
embedded or trailing binary zeros (null delimiters). Keys formed solely
from the KEY IS clause without the use of SETURLKEY have a binary zero
after each concatenated part of the key. If you want to eliminate the
embedded/trailing delimiters between parts of a key, you must use
SETURLKEY to create the partitioning key.
DATASTORE kafka://.../...[/<partition> |/key |/root_key |/]Category
Specialized
Syntax
SETURLKEY(<target_datastore>, <concatenated_key>)
Parameter and Description
| Parameter | Description |
|---|---|
| <concatenated_key> | Any combination of literals, variables, source alias references and source data concatenated to create a partitioning key. |
Best Practices
- In order for partitioning keys to be given to Kafka when writing a message, regardless of the method used to create them, the KEY IS clause must be specified on a DESCRIPTION or target DATASTORE statement. One or more column or field names may be specified, and each must exist in the description.Note: A dummy or placeholder name cannot be used.The KEY IS clause must be present and valid, even if you intend to override it using SETURLKEY.
- If you want the key to be formed automatically from the column or field names specified on the KEY IS clause, specify the Kafka URL with /key or /root_key at the end. The key will have a null terminator (Unicode \u0000) at the end of each part of the key.
- If you want to create the key dynamically using SETURLKEY:
- specify a non-generic topic name in the URL (i.e., no asterisk)
- terminate the URL with a slash '/'
- do not code /key or /root_key in the URL
- SETURLKEY cannot be used with a generic URL.
Examples
Example 1
Partition Kafka topics using both the both the source data key and the
abbreviated State from the source table change data
records.
DESCRIPTION DB2SQL ./DB2DDL/EMP.ddl AS EMP;
DESCRIPTION DB2SQL ./DB2DDL/DEPT.ddl AS DEPT;
DATASTORE kafka:///dummy_topic/
CREATE PROC P_EMP AS SELECT
{
SETURLKEY(TARGET, STRING(EMP.STATE_ABRV, EMP.EMP_NO))
REPLICATE(TARGET, EMP)
}
CREATE PROC P_DEPT AS SELECT
{
SETURLKEY(TARGET, STRING(DEPT.STATE_ABRV, DEPT.DEPT_NO))
REPLICATE(TARGET, DEPT)
}Example 2
Partition Kafka topics using both the both the source data key and the IMS Source System Instance from the source segment change data records.
-- Define the source as IMS change data and the target as
Kafka
DESCRIPTION IMSDBD ./IMSDBD/HREMPLDB.dbd AS HREMPLDB;
BEGIN GROUP IMS_SEG;
DESCRIPTION COBOL ./IMSSEG/EMPLOYEE.cob AS EMPLOYEE
FOR SEGMENT EMPLOYEE
IN DATABASE HREMPLDB
;
END GROUP;
DATASTORE kafka:///dummy_topic/ -- specify dynamic topic
OF JSON
AS TARGET
DESCRIBED BY GROUP IMS_SEG -- use source for REPLICATE
;
CREATE PROC P_EMPLOYEE AS SELECT
{
V_SOURCE_SYSTEM_INSTANCE = CONVERT_CCSID(X2C(LEFT(CDCUOW(CDCIN),8)),1208,1047)
SETURLKEY(TARGET, STRING(V_SOURCE_SYSTEM_INSTANCE,EMPLOYEE.EMP-NO))
REPLICATE(TARGET, EMP)
}