mirror of
https://github.com/microsoft/BCQuality.git
synced 2026-08-06 17:36:53 +01:00
0e06485027
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 667c64a8-eb36-4440-bc41-6a97d8fb5542 Co-authored-by: Jesper Schulz-Wedde <jesper.schulzwedde@microsoft.com>
28 lines
1.4 KiB
Markdown
28 lines
1.4 KiB
Markdown
---
|
|
bc-version: [all]
|
|
domain: performance
|
|
keywords: [setloadfields, case, conditional, branch, field-loading]
|
|
technologies: [al]
|
|
countries: [w1]
|
|
application-area: [all]
|
|
---
|
|
|
|
# Load common fields before branching on case
|
|
|
|
> Contributions welcome — open a PR to refine or extend this article.
|
|
|
|
## Description
|
|
|
|
When a known input determines which fields a subsequent record read will use, a single `SetLoadFields` containing every branch's fields loads unnecessary columns. Build the selection before `Get`, `FindFirst`, or `FindSet`: use `SetLoadFields` for fields common to every branch, then `AddLoadFields` for the selected branch. `SetLoadFields` replaces the current selection, while `AddLoadFields` preserves it.
|
|
|
|
## Best Practice
|
|
|
|
Call `SetLoadFields` with the common fields. In each branch, call `AddLoadFields` with that branch's normal fields and then perform the record read. This applies only when the discriminator is known before the read; branching on a field from an already-loaded row is too late to tailor that row's initial SQL projection.
|
|
|
|
See sample: `load-common-fields-before-branching-on-case.good.al`.
|
|
|
|
## Anti Pattern
|
|
|
|
A single top-level `SetLoadFields` enumerating every branch's fields, or a branch-local `SetLoadFields` that accidentally discards the common selection. Both make the declared load plan differ from the fields the selected path actually uses.
|
|
|
|
See sample: `load-common-fields-before-branching-on-case.bad.al`.
|