Overview

You can perform various types of "join" applications on two files (F1 and F2) by one or more keys with DFSORT using the following statements:

JOINKEYS: You must specify two JOINKEYS statements; one for the F1 file and another for the F2 file. A separate subtask will be used to process each file and a main task will be used to process the joined records from the two files.
Each JOINKEYS statement must specify the ddname of the file it applies to and the starting position, length and sequence of the keys in that file. You can also optionally specify if the file is already sorted by the keys and if sequence checking of the keys is not needed; if the file has fixed-length or variable-length records; to stop reading the file after n records; a 2-byte id to be used for the message and control data set for the subtask used to process the file, and if a subset of the records is to be processed based on a logical expression.
JOIN: If you don't specify a JOIN statement, only paired records from F1 and F2 are kept and processed by the main task as the joined records (inner join). You can optionally specify a JOIN statement to have the main task keep and process: unpaired F1 records as well as paired records (left outer join); unpaired F2 records as well as paired records (right outer join); unpaired F1 and F2 records as well as paired records (full outer join); only unpaired F1 records; only unpaired F2 records, or only unpaired F1 and F2 records.
REFORMAT: You would normally specify a REFORMAT statement to indicate the F1 and/or F2 fields you want in the joined records. You can optionally specify an indicator of where the key was found, and a FILL character to be used for missing bytes. If a JOIN statement with ONLY is specified, the REFORMAT statement is optional.

F1 and F2 can be any type of sequential or VSAM file supported by DFSORT for SORTIN and can have different attributes (for example, F1 can have RECFM=FB and LRECL=100 and F2 can have RECFM=VB and LRECL=254, or F1 can be a VSAM ESDS and F2 can be a PDS member).

F1 will be sorted or copied by "subtask1". An E35 exit will be used to pass the needed fields from the F1 records to the "main task" (an intermediate output data set is not used or required). A subset of the DFSORT statements, such as INCLUDE, OMIT, INREC, SUM and OPTION, will be available for processing the F1 records.

F2 will be sorted or copied by "subtask2". An E35 exit will be used to pass the needed fields from the F2 records to the "main task" (an intermediate output data set is not used or required). A subset of the DFSORT statements, such as INCLUDE, OMIT, INREC, SUM and OPTION, will be available for processing the F2 records.

The "main task" will use an E15 to join the records passed from the E35 of subtask1 and E35 of subtask2. The joined records will be processed as the input records for a sort or copy application. Most of the control statements and options available for a DFSORT sort or copy application will be available for processing the joined records.

Note: Since a JOINKEYS application uses three tasks, it can require more storage than a regular DFSORT application. You may need to use REGION=0M for some JOINKEYS applications.