Rational Developer for System z

Working with large data sets

The Data Editor provides the ability to open and step through very large data sets whose contents cannot easily be transferred and stored in local memory.

To allow for editing of these data sets, the Data Editor attempts to open and display a small subset of records from the selected data set at a time. If a particular record is not displayed in the initial subset, the Data Editor provides the ability to traverse through the remaining records in the data set by stepping ahead or back a predetermined number of records. Performing a step refreshes the editors current view to show the next series of records in a targeted data set while removing a portion of the already displayed records from the screen.

For example, suppose the editor is configured to display 200 records at a time and has a step size of 50 records. If a data set is opened that contains 1,000 records, the records 1 - 200 will be displayed first. When a step down is performed to view the remaining records in the data set, the editor refreshes to view the records 50 - 250.

This process allows for very large data sets to be opened and manipulated without their large size affecting performance. The number of records that are initially opened and displayed and the record step size in the editor can all be configured with the Editor data set step size (Records) and Editor data set window size (Records) preferences.

In order to step through a data set, there are two buttons located in the toolbar of the editor.
Move Window Down
The editor to step down a predetermined number of records
Move Window Up
The editor to step back up the same predetermined number of records
To help keep track of your location within the data set, the editor provides a record range status window at the bottom of the editor that identifies the current portion of records being displayed out of the total records in the data set.

When modifying records at varying points in a very large data set, it is not necessary to perform a save before stepping through the data set. When modifications are made to records such as editing data, deleting, or adding new records, the Data Editor will maintain these modifications as you traverse through the data set, placing the records in question potentially out of the editors view. Although not necessary, saving before stepping up or down is recommended to help reduce the number of changes being sent to the Host at once, and also to reduce the number of records that need to be maintained locally.


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