Microsoft/bcquality
1
0
Fork 0
mirror of https://github.com/microsoft/BCQuality.git synced 2026-10-05 14:46:55 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions 4
bcquality/microsoft/knowledge/performance/avoid-get-inside-loop-on-large-table.md
Jesper Schulz-Wedde 2b5550c346
Some checks failed
Validate knowledge index / validate-index (push) Has been cancelled
Details
Validate AL review fixtures / validate-review-fixtures (push) Has been cancelled
Details
Validate frontmatter and structure / validate (push) Has been cancelled
Details
Improve partner onboarding and documentation navigation (#174) 
Lead with a complete plugin quick start and add task-oriented usage, troubleshooting, customization, and contribution guides. Preserve the broader plugin framing, correct conflicting contract guidance, support Agents folder reviews, and align repository validation. Convert existing sample references to clickable links without changing knowledge rules.

Co-authored-by: Jesper Schulz-Wedde <jesper.schulzwedde@microsoft.com>
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
2026-09-09 17:31:03 +02:00

1.4 KiB
Raw Blame History

bc-version domain keywords technologies countries application-area
all
performance
n-plus-one
get
findfirst
loop
inner-lookup
large-table
al
w1
all

Avoid Get / FindFirst inside a loop on a large inner table

Description

A Get or FindFirst against another persistent table inside a loop can produce an N+1 access pattern: one outer query followed by repeated inner lookups. Server and primary-key caches can satisfy some Get calls, so a source-level Get is not proof of one SQL round-trip. The concern is an unbounded loop whose lookup keys are not known to repeat or remain cached.

Best Practice

Use a query object to join the outer and inner tables when the relationship and filters can be expressed as one query. If keys repeat, a dictionary cache can reduce lookups to one per distinct key. SetLoadFields can reduce the columns transferred by unavoidable inner reads, but it does not eliminate the N+1 shape and must not be presented as doing so.

See sample: avoid-get-inside-loop-on-large-table.good.al.

Anti Pattern

Iterating production BOM lines and calling Item.Get(BOMLine."No.") for each line when the same result can be produced by a query joining Production BOM Line to Item. Partial loading alone is only a payload mitigation for this pattern.

See sample: avoid-get-inside-loop-on-large-table.bad.al.