bcquality/microsoft/knowledge/performance/use-isempty-for-existence-checks.md
Jesper Schulz-Wedde 9a4198eb28 Add [all] sentinel to bc-version; apply to version-agnostic knowledge
Most of the corpus — FindSet/SetLoadFields/CalcFields patterns, permission
sets, SingleInstance codeunits, DataClassification, IsolatedStorage,
transaction scope, SecretText — describes BC platform behaviour that is
identical across supported versions. The seed [26..28] range on every
file implied a version-specificity the content does not actually have,
and there was no way to express "applies to every version" in the
schema the way [w1] and [all] already do for countries and
application-area.

Extend the v1 schema with a universal sentinel for bc-version, parallel
to the sentinels already defined for the other dimensions:

  bc-version: [all]         # applies to every BC version

[all] is mutually exclusive with explicit versions. Range shorthand
([26..28]) and explicit lists ([26, 27, 28]) continue to work for files
genuinely tied to a version-gated API or deprecation.

Update read.md (field definition, matching semantics, partial-context
rule), write.md (default to [all], use ranges only with a concrete
reason), README.md (frontmatter example), and the CI validator. All
forty existing knowledge files and the three action skills convert to
[all]; none of the current content is version-gated. Validator passes.
2026-04-23 16:00:03 +02:00

1.1 KiB

bc-version domain keywords technologies countries application-area
all
performance
isempty
count
findfirst
existence
al
w1
all

Use IsEmpty for existence checks

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

IsEmpty is the cheapest way to answer whether at least one row matches the current filters. It short-circuits at the first match and never hydrates a record. Count() scans and counts the entire set; FindFirst fetches a full row just to be discarded.

Best Practice

Use if not Rec.IsEmpty() then ... for existence checks. Reserve Count for cases where the exact number of rows is needed, and FindFirst for cases where you actually want the row's field values.

See sample: use-isempty-for-existence-checks.good.al.

Anti Pattern

if Rec.Count() > 0 iterates the whole set just to answer a yes/no question. if Rec.FindFirst() then loads an entire row of data the caller never reads.

See sample: use-isempty-for-existence-checks.bad.al.