A relational source qualifier can receive data from multiple source tables. The Integration Service creates SQL queries for database partitions based on the number of partitions in the database table with the most partitions. It creates an SQL join condition to retrieve the data from the database partitions.
For example, a source qualifier receives data from two source tables. Each source table has two partitions. If the session has three partitions and the database table has two partitions, one of the session partitions receives no data.
The Integration Service generates the following SQL statements for Oracle:
Session Partition 1:
SELECT <column list> FROM t1 PARTITION (p1), t2 WHERE <join clause>
Session Partition 2:
SELECT <column list> FROM t1 PARTITION (p2), t2 WHERE <join clause>
Session Partition 3:
No SQL query.
The Integration Service generates the following SQL statements for IBM DB2:
Session Partition 1:
SELECT <column list> FROM t1,t2 WHERE ((nodenumber(t1 column1)=0) AND <join clause>
Session Partition 2:
SELECT <column list> FROM t1,t2 WHERE ((nodenumber(t1 column1)=1) AND <join clause>
Session Partition 3:
No SQL query.