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table.transform() now raises a TransactionError if it's called inside an open transaction with PRAGMA foreign_keys enabled when the table is referenced by foreign keys with destructive ON DELETE actions (CASCADE, SET NULL, or SET DEFAULT).

sqlite-utils 4.1.1 adds a safety check that stops table.transform() from running when it could silently trigger destructive cascading foreign key actions during an open transaction. ✦ AI generated

Simon Willison · Simon Willison's Weblog · 2026-07-12 · original ↗

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table.transform() now raises a TransactionError if called while a transaction is open with PRAGMAforeign_keys enabled and the table is referenced by foreign keys with destructive ON DELETE actions - CASCADE, SET NULL or SET DEFAULT.

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✳ sqlite-utils ✳ table.transform()

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Mechanism · 1

Because PRAGMA foreign_keys cannot be changed inside an open transaction, dropping the old table as part of table.transform() could previously fire destructive ON DELETE actions and silently delete or modify rows that referenced that table.Simon Willison · Simon Willison's Weblog · conf 85%

Context · 1

table.transform() implements the SQLite-documentation-recommended pattern for altering tables beyond what ALTER TABLE supports: create a new temp table with the new schema, copy the data across, then drop the old table and rename the new one into place.Simon Willison · Simon Willison's Weblog · conf 60%