1.8 KiB
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Use SetLoadFields for partial records
Description
SetLoadFields instructs the platform to hydrate only the listed fields on a record variable. On wide tables, or tables with BLOB or media fields, the difference is substantial: a Sales Invoice Line has dozens of fields and loading all of them for every row of a large set is wasted bandwidth. Primary key fields, SystemId, and system audit fields are always loaded automatically. SetLoadFields works only with FieldClass = Normal; FlowFields and FlowFilters cannot be partial-loaded.
Best Practice
Call SetLoadFields before FindSet, FindFirst, or Get when the table is wide enough to matter (roughly 10+ fields) and the code path reads a small subset (roughly under 60%) across a material number of rows. Short loops over narrow tables usually do not earn the extra coupling; see skip-setloadfields-on-narrow-tables-and-short-loops for that exception. List every field that is read or written during the operation, including fields used in calculations and downstream function calls. Omitting a field that is later accessed triggers a second round-trip.
Fields that appear only in SetRange or SetFilter calls do not need to be included — the database resolves the filter using the index without hydrating the value into AL memory. Including filter-only fields wastes bandwidth and is not required.
See sample: use-setloadfields-for-partial-records.good.al.
Anti Pattern
Iterating a large set and reading only two or three fields without SetLoadFields forces the platform to transport every column for every row, including BLOBs and unused text fields.
See sample: use-setloadfields-for-partial-records.bad.al.