VSAM Connector uses group source processing to read bulk data from ESDS, KSDS, or RRDS data sets with multiple record types.
Group source processing reads data that is stored in the same physical source in a single pass. By eliminating multiple passes of the source data, group source processing enhances bulk data movement performance and reduces resource consumption on the source system.
You can use the browser-based Informatica Intelligent Cloud Services interfaces to define VSAM connections, mappings, and mapping tasks.
With Informatica Intelligent Cloud Services interfaces, you gain access to easy-to-use, browser-based interfaces for defining mappings and mapping tasks and running and monitoring mapping tasks. When you run the mapping and mapping tasks, VSAM Connector components, in conjunction with Data Integration, read and process the records that VSAM Connector read from the VSAM data set.
VSAM Connector can move bulk data from the following types of VSAM data sets:
Entry-sequenced data set (ESDS)
A data set that stores records in the order in which they were created, with the latest records at the end. ESDSs have no index. ESDS records can be accessed directly by using a relative byte address (RBA) or sequentially based on entry sequence. VSAM Connector accesses ESDS data sets sequentially.
Key-sequenced data set (KSDS)
A data set that contains records that are loaded in key sequence and controlled by an index. KSDSs can be accessed directly by using a key or RBA or sequentially based on key sequence.
By default, VSAM Connector accesses KSDS records sequentially if no WHERE clause is specified.
VSAM Connector accesses records by using a key under the following conditions:
- A WHERE clause is specified.
- The primary field in the KSDS key is used in one of more WHERE clause conditions.
For example, VSAM Connector uses keyed access to perform a PowerCenter Lookup transformation that uses a KSDS lookup source when the lookup condition includes question marks that are substituted at run time. VSAM Connector always uses a key to access a KSDS file if possible when processing a WHERE clause.
VSAM Connector can access KSDS files through an alternate index that you specify by using a file name override. VSAM Connector determines whether to use keyed or sequential access at run time after it opens the file and determines the start position and length of the key.
When you define the data map, you can optimize the data map for sequential access by enabling CI access and setting the number of data buffers to a high value. You can optimize the data map for keyed access by setting the number of index buffers to a high value and the Number of data buffers to a low value, such as 2.
Relative record data set (RRDS)
A data set that contains fixed-length records. RRDSs are accessed sequentially or directly by using a relative record number (RRN). VSAM Connector accesses RRDS data sets sequentially based on RRN.
Variable-length relative record data set (VRRDS)
A data set that contains variable-length records. VRRDSs can be accessed sequentially or directly by using a relative record number (RRN). VSAM Connector accesses VRRDS records sequentially based on RRN.
PowerExchange can process VSAM data sets that are in basic or extended format. PowerExchange can also processes data sets that contain compressed data.
Because VSAM is not a relational database, you must create a data map in the PowerExchange Navigator. VSAM Connector uses the data map to access VSAM data and metadata and to create a relational row-type view of the records. VSAM Connector requires a relational view to use SQL‑type statements to read or write bulk data.
When you create VSAM data maps, you must select the access method that corresponds to the VSAM data set type. The following VSAM access methods are available:
•ESDS
•KSDS
•RRDS, for both fixed-length and variable-length relative record data sets
If a copybook is available for the VSAM data set, you can import it for the data map to get a detailed layout of each record. If you do not import a copybook, you will need to manually define the fields in the VSAM records.
Also, you must run a PowerExchange Listener on the MVS system where the VSAM source or target is located. Verify that this PowerExchange Listener can communicate with the system or systems where the PowerExchange Navigator, PowerCenter Client, and PowerCenter Integration Service run.