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Ports 14 concern-sized articles (8 performance, 6 security) and 25
AL samples from BC Code Intelligence, restructured to BCQuality's v1
schema and layered under /community/knowledge/. Each article is
atomic, under 100 lines, and ships <slug>.good.al and (where the
pattern has a clear anti-example) <slug>.bad.al siblings.
Jesper's microsoft-layer leaves (al-performance-review and
al-security-review) source across every enabled layer via
*/knowledge/<domain>/**, so these additions are picked up by the
existing action skills without any new skill definitions.
Performance (8):
- use-deleteall-for-filtered-bulk-deletion
- call-setloadfields-before-filters
- load-common-fields-before-branching-on-case
- load-only-primary-key-fields-for-reference-work
- omit-filter-only-fields-from-setloadfields
- choose-maintainsiftindex-by-read-write-ratio
- avoid-growing-globals-in-singleinstance-subscribers
- order-case-branches-by-frequency
Security (6):
- classify-every-field-with-dataclassification
- protect-sensitive-data-in-temporary-tables
- guard-bulk-operations-with-istemporary
- compose-permission-sets-with-included-sets
- do-not-grant-rights-beyond-a-users-entitlement
- prefer-oauth2-over-api-keys-for-external-http-calls
Graveyard-bound items (not ported; to be captured in a later
/docs/triage-graveyard.md):
- testfield-performance (soft guidance, low actionability)
- table-event-batch-operation-impact (keep-event-subscribers-lightweight
already carries the core insight)
- Most of /roger-reviewer (AL formatting - frontier-model territory)
- sift-technology-fundamentals (descriptive, not a citable concern)
- bc-telemetry-buddy-* (tooling promotion, not guidance)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
28 lines
1.6 KiB
Markdown
28 lines
1.6 KiB
Markdown
---
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bc-version: [26..28]
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domain: performance
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keywords: [case, branch, frequency, control-flow, hot-path]
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technologies: [al]
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countries: [w1]
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application-area: [all]
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---
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# Order case branches by frequency
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> **Seed article.** Ported from BC Code Intelligence to seed the community corpus. Community contributors are invited to expand or refine.
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## Description
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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.
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## Best Practice
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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.
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See sample: `order-case-branches-by-frequency.good.al`.
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## Anti Pattern
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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.
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See sample: `order-case-branches-by-frequency.bad.al`.
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