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Programming Interfaces
Data Management : Database Access : Fetching field lists

Fetching field lists

When fetching records with a FOR EACH statement or query, the AVM typically retrieves all the fields of a record, whether or not your application needs them. This can have a costly impact on performance, especially when browsing records over a network.
ABL automatically optimizes preselected and presorted fetches from remote OpenEdge databases using field lists. A field list is a subset of the fields that define a record and includes those fields that the client actually requires from the database server. For preselected and presorted fetches, ABL can deduce this field list at compile time from the code.
You can also specify field lists explicitly for many types of AVM record fetches, including:
*FOR statements
*DO PRESELECT statements
*SQL SELECT statements
This section explains how to use field lists in ABL. For information on specifying field lists in SQL SELECT statements, see OpenEdge Data Management: SQL Development.
* Field list benefits
* Specifying field lists in ABL
* Avoiding implied field list entries
* Updating and deleting with field lists
* Cursor repositioning and field lists
* Field list handling in degenerate cases