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bcquality/microsoft/knowledge/upgrade/datatransfer-for-bulk-init.md
Jesper Schulz-Wedde 34c931e1c1
Fix knowledge corpus integrity issues (#87) 
Repair broken knowledge references and align review examples with canonical articles. Correct explicit version gates, restore a missing title, and recognize the plugin directory in the root guard.

Co-authored-by: Jesper Schulz-Wedde <jesper.schulzwedde@microsoft.com>
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
2026-07-13 10:34:23 +02:00

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upgrade
datatransfer
large-dataset
bulk-update
modifyall
copyfields
new-field
al
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Use DataTransfer for bulk updates on large tables

Description

Tables that can contain more than 300,000 records, and any newly added field on an existing table, should be initialized with DataTransfer rather than a repeat ... Modify ... until Next() = 0 loop. DataTransfer issues a single set-based statement to the database; the loop/modify pattern issues one round-trip per row and accumulates write locks for the duration of the upgrade. On the volumes that drive upgrade pain — ledger entries, item ledger entries, price list lines — the difference is the upgrade running for minutes instead of hours.

Best Practice

For a bulk update use a DataTransfer variable: call SetTables(Database::"...", Database::"...") (source and destination may be the same table), add filters with AddSourceFilter, set the target value with AddConstantValue (or copy a source field with AddFieldValue), and execute with CopyFields(). To express multiple distinct updates against the same table, Clear the DataTransfer between executions and configure the next one.

See sample: datatransfer-for-bulk-init.good.al.

Anti Pattern

Iterating with FindSet(true) ... repeat ... Modify() ... until Next() = 0 to set a single field across an entire large table. On 300k+ rows this is the canonical slow-upgrade footgun.

See sample: datatransfer-for-bulk-init.bad.al.

See also

  • datatransfer-skips-triggers-and-subscribers.md — DataTransfer does not raise field validation triggers or event subscribers; if a row needs validation logic, DataTransfer is the wrong tool.