bcquality/microsoft/knowledge/privacy/no-pii-in-telemetry-message-string.md
Jesper Schulz-Wedde a9f3c50863 Regenerate microsoft/knowledge from upstream BCApps instructions
The previous LLM-generated knowledge files contained factual
hallucinations. The most visible was the claim that `FindFirst` /
`FindLast` "forces a full-table scan" on an unfiltered record - it does
not; those APIs return a single row via the current key.

Other inaccuracies the audit found and fixed:

* `FindSet(true)` was described as "taking a LockTable". The correct
  upstream phrasing is that `FindSet(true)` sets
  `ReadIsolation::UpdLock` on the read. UpdLock and LockTable are
  related but distinct mechanisms.
* The list of production-scale tables had been invented beyond the
  upstream source (e.g. "Detailed Cust. Ledg. Entry") without a
  citation. The regenerated list matches the ten tables upstream lists
  with their P95 row counts.
* `SetLoadFields` guidance had been augmented with an extra mechanism
  claim ("the database resolves the filter using the index without
  hydrating the value") not present in upstream.

Approach: full regeneration of `microsoft/knowledge/` from the six
upstream BCApps Code Review instruction files, with Microsoft Learn /
the AL language reference as a secondary source. Every claim in every
regenerated file is anchored to a verbatim upstream quote (or a Learn
URL); the audit trail lives in artifacts/trace-<domain>.json on the
session workspace.

The PR #11 transaction/error-handling cluster is preserved verbatim:

* performance/understand-implicit-transaction-boundary.md
* performance/codeunit-run-as-atomic-sub-operation.{md,good.al,bad.al}
* performance/codeunit-run-requires-prior-commit-inside-transaction.{md,good.al,bad.al}
* performance/use-tryfunction-for-error-catching-not-rollback.{md,good.al,bad.al}
* performance/avoid-commit-inside-loops.{md,good.al,bad.al}
* security/commitbehavior-attribute-scopes-explicit-commits.{md,good.al,bad.al}
* testing/transactionmodel-attribute-governs-test-transactions.{md,good.al,bad.al}

These articles already cite Microsoft Learn and were carefully
cross-referenced; the regeneration skips their topics rather than
duplicating them.

File counts after regeneration:

  performance   35 .md  (5 preserved + 30 new)
  privacy       17 .md
  security      18 .md  (1 preserved + 17 new)
  style         33 .md
  testing        1 .md  (preserved)
  ui            19 .md
  upgrade       18 .md

Total 141 atomic knowledge files, each strictly one rule. All pass
.github/scripts/validate_frontmatter.py with 0 errors and 0 warnings.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
2026-05-21 09:53:09 +02:00

1.6 KiB

bc-version domain keywords technologies countries application-area
all
privacy
telemetry
session-logmessage
strsubstno
pii
customer-data
employee-code
filename
al
w1
all

Do not embed customer data in the telemetry message text

Description

Session.LogMessage's message argument is a plain Text. Unlike Error(), the platform does not inspect this string field-by-field — whatever is in the text is what telemetry receives. So a call that builds the message via StrSubstNo from customer-bearing fields ships those values to telemetry verbatim, regardless of the DataClassification argument on the same call. Flagged content includes customer names, email addresses, phone numbers, addresses, employee codes or IDs, attachment filenames, user-provided text that may carry PII, and dumps of Record content.

Best Practice

Keep the telemetry message a static, non-personal string ("Customer record processed", "Error processing uploaded file"). When structured context is genuinely needed, attach it through custom dimensions, where individual values can be reviewed and classified at the dimension level rather than baked into a free-text message.

See sample: no-pii-in-telemetry-message-string.good.al.

Anti Pattern

Session.LogMessage('0000', StrSubstNo('Processed %1', Customer.Name), ...) — the customer name is in telemetry the moment the line runs. Detection signal: a StrSubstNo whose result is the second argument of Session.LogMessage. The same shape with FileName, EmployeeCode, or any record field is the same problem.

See sample: no-pii-in-telemetry-message-string.bad.al.