When PowerExchange performs a multiple-record write, it preserves source sequencing information. To enable multiple-record writes with sequencing, select the

Multi-Record Datamaps

and

Use Sequence Fields

options in the

Import from PowerExchange

dialog box for both the source and target definitions.

You can perform a multiple-record write from a VSAM ESDS, KSDS, or RRDS source to the following target types:

VSAM ESDS, KSDS, or RRDS data sets on z/OS
Sequential data sets on z/OS
Files on i5/OS
Files on Linux, UNIX, and Windows

To perform multiple-record writes with sequencing, PowerExchange uses group source processing to read source data in a single pass and uses group target processing to write data to the target in a single pass.

PowerExchange generates sequence fields to pass metadata about the source record relationships to the target. After you enable multiple-record writes with sequencing for a PowerCenter workflow, the workflow can read the multiple-record source, use the generated sequence fields to preserve the sequencing information, and write data to the target in the same record sequence as in the source.

To determine the relationships among records for sequential file and VSAM sources and generate sequence fields, PowerExchange uses the record properties that you define in the data map. These record properties include the parent record name, the name of the base record that the current record redefines, and whether the record is a header or trailer record. PowerExchange uses these record properties to generate primary and foreign keys and sequencing metadata in the source and target definitions.

When you run a PowerCenter session, PowerExchange uses the generated key values to reconstruct and write the data to the target in the correct sequence. PowerExchange maintains the data in a sequencing and queuing cache on the Integration Service node. When PowerExchange writes data to the target, it deletes the generated key fields and sends the data across the network in the correct sequence to the target file.