Extracting data
With Extract (option 3.3), you can extract all or selected segments from an IMS database, and save them to a sequential data set. After extracting the segments, you can use Load (option 3.4) to load them into another IMS database.
The types of extracts that can be performed are:
- A full database extract, including a full extract of any logically related databases.
- A partial database extract, containing segments selected
by a combination of:
- A file containing the root segment key values to determine
the database records you want to extract.
You can create this file when editing a database, by entering the XKEY command.
- Extract criteria specifying the segments you want to extract and field selection criteria to select the database records to be extracted.
- Relationship criteria specifying how logical segments are chased.
- A file containing the root segment key values to determine
the database records you want to extract.
Here are two example uses for Extract:
- Creating a small test database from a large production database
- You can extract a relatively small number of segments from a large production database, then load those segments into a separate database for application testing.
- Querying the database
- You can use a combination of criteria to extract only those segments whose fields match particular values.
To print a formatted extract of the IMS Segments, use the IPR (IMS print) function.
Note: The Extract utility can use a Dynamic PSB or a
Static PSB.
The tasks described in this section are: