Microsoft/bcquality
1
0
Fork 0
mirror of https://github.com/microsoft/BCQuality.git synced 2026-08-06 09:26:52 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions

Promote performance knowledge from community to Microsoft layer (#50)

Browse source 
Pure git-mv relocation of all 7 performance articles from community/knowledge/performance/ to microsoft/knowledge/performance/. No content changes.

Co-authored-by: Jesper Schulz-Wedde <jesper.schulzwedde@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
This commit is contained in:
Jesper Schulz-Wedde 2026-07-01 10:41:01 +02:00 • committed by GitHub
parent 24e62f5ec8
commit 292bdabe27
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
20 changed files with 0 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

28
community/knowledge/performance/order-case-branches-by-frequency.md
View file

@ -1,28 +0,0 @@
---
bc-version: [all]
domain: performance
keywords: [case, branch, frequency, control-flow, hot-path]
technologies: [al]
countries: [w1]
application-area: [all]
---
# Order case branches by frequency
> Contributions welcome — open a PR to refine or extend this article.
## Description
The AL `case` statement evaluates branches in the order they appear. When the distribution of the discriminator is heavily skewed — one or two values handle the vast majority of records, and the rest handle edge cases — the average cost of the statement is dominated by how many branches precede the common one. For evenly distributed discriminators the order does not matter; for skewed distributions it changes the hot-path cost of every call site.
## Best Practice
Where the runtime frequency of values is known or measurable, list the common branches first. An `else` arm that handles unexpected values belongs last. When the common branch is also the simplest to evaluate, the placement compounds: the hot path is both short and cheap, and the uncommon branches are never touched on typical records.
See sample: `order-case-branches-by-frequency.good.al`.
## Anti Pattern
Ordering branches alphabetically, by enum declaration order, or by "logical grouping" when the runtime distribution is heavily skewed. Every common record pays the cost of evaluating every uncommon branch first; on a posting routine processing thousands of rows the overhead is measurable.
See sample: `order-case-branches-by-frequency.bad.al`.