bcquality/microsoft/knowledge/performance/add-sift-keys-for-flowfields.md
Jesper Schulz-Wedde 32c40bbf1d Seed performance knowledge corpus (22 articles + AL samples)
Converts an existing performance-review prompt into 22 atomic
knowledge articles under microsoft/knowledge/performance/, each
paired with AL samples under samples/performance/<slug>/ demonstrating
the anti-pattern and/or the best practice. The full set seeds the
corpus the microsoft/skills/al-performance-review leaf skill matches
against and validates the READ knowledge-file format end-to-end.

Every article conforms to the READ contract: six required frontmatter
fields, Description always present, no fenced code blocks, sample
code referenced by repo-relative path. Each article is marked with a
blockquote 'Seed article' note so domain stewards can extend or
restructure them freely.

Articles (ordered by concern area):

Database query efficiency
- use-findset-with-next (AA0181)
- avoid-findfirst-with-next (AA0233)
- only-fetch-records-you-use (AA0175)
- use-findset-readonly-by-default
- use-setloadfields-for-partial-records
- use-addloadfields-in-report-layouts
- use-calcsums-to-aggregate-filtered-sets (file: use-calcsums-for-flowfield-totals.md)
- avoid-calcfields-in-loops
- add-sift-keys-for-flowfields (AA0232)
- use-isempty-for-existence-checks

Filter and key optimization
- filter-before-find
- set-current-key-to-match-filters

Temporary tables and transactions
- use-temporary-tables-for-intermediate-data
- keep-transaction-scope-short
- avoid-user-interaction-in-transactions
- avoid-commit-inside-loops

Record operations
- prefer-get-for-primary-key-lookups
- use-insert-false-when-skipping-triggers
- prefer-direct-record-over-recordref

Strings, codeunits, events
- use-strsubstno-for-message-formatting
- use-single-instance-codeunits-for-caching
- keep-event-subscribers-lightweight

samples/README.md documents the sample-folder convention and makes
clear the samples are demonstration-only, not derived from BC base
application source, with unique object IDs in the 50100-50199 range.

Rubber-duck pass caught: a misleading good.al in avoid-calcfields-in-loops
(fixed by switching to a hoistable CalcFields scenario), an invalid
event subscriber signature in keep-event-subscribers-lightweight
(fixed by adding var xRec), normative guidance leaked into the
Description of use-findset-readonly-by-default (moved to Anti Pattern),
a missing sample pair for keep-transaction-scope-short (added), and
muddy FlowField/CalcSums framing (retitled and clarified).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
2026-04-17 13:23:34 +02:00

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Markdown

---
bc-version: [26..28]
domain: performance
keywords: [sift, sumindexfields, flowfield, key, aa0232]
technologies: [al]
countries: [w1]
application-area: [all]
---
# Add SIFT keys for FlowField aggregations
> **Seed article.** Converted from an existing performance-review prompt to bootstrap the BCQuality performance corpus. Domain stewards should expand, restructure, and refine as needed.
## Description
CodeCop rule AA0232 checks that FlowFields backed by CalcSums or aggregation CalcFormula are supported by a key whose SumIndexFields include the summed field and whose key prefix matches the formula's filter fields. Without a SIFT key the platform falls back to a full aggregation on every read — typically invisible in development and catastrophic in production.
## Best Practice
For each Sum-style FlowField, ensure the source table has a key whose leading fields match the FlowField's CalcFormula WHERE clause and whose SumIndexFields list includes the summed field. Table extensions adding new FlowFields are responsible for adding the supporting key.
See sample: `samples/performance/add-sift-keys-for-flowfields/good.al`.
## Anti Pattern
Declaring a FlowField on a hot table without checking whether a supporting SIFT key exists ships a latent scan into every list page and report that touches the field.