The triggered_data_change_violation error occurs when a PostgreSQL trigger tries to perform a data-modifying statement that the SQL standard forbids during the original data-change event.
PostgreSQL Error 27000 – triggered_data_change_violation appears when a BEFORE or AFTER trigger issues an INSERT, UPDATE, or DELETE that conflicts with SQL rules for triggered data changes, often on the same table. Refactor the trigger logic or defer the operation to resolve the error.
PostgreSQL Error 27000
PostgreSQL raises SQLSTATE 27000 – triggered_data_change_violation – when a trigger performs a forbidden data-modifying action while the original statement is still running. The SQL standard blocks such recursive or conflicting writes to protect data integrity.
The error most often surfaces in BEFORE or AFTER row triggers that call INSERT, UPDATE, or DELETE on the same table, or on tables referenced by transition tables in statement-level triggers.
Fixing it quickly is vital because it can roll back the entire transaction.
Typical output: ERROR: 27000: triggered_data_change_violation – cannot INSERT into table "orders" during BEFORE UPDATE on "orders". The table name and operation change with context but the SQLSTATE remains 27000.
Recursive writes are the primary cause. A trigger that fires on table A and then tries to modify A again will violate SQL rules.
PostgreSQL blocks the second write and throws 27000.
Modifying transition tables inside a statement-level trigger can also provoke the error. The same happens when a trigger tries to run DDL that implies data change, such as ALTER TABLE ... TRUNCATE PARTITION.
First, audit the trigger body to remove direct modifications on the table that fired the trigger.
If the change is required, move the logic to an AFTER COMMIT procedure or a background job.
Alternatively, mark the trigger as DEFERRABLE and set SET CONSTRAINTS ALL DEFERRED; so PostgreSQL delays the second write until commit time, when recursion risk is gone.
Auditing columns – Use NEW/OLD records inside the same row instead of issuing UPDATE on the table.
Maintaining aggregates – Write to an auxiliary summary table instead of the base table, or call PERFORM pg_notify(...) and aggregate asynchronously.
Keep triggers small and side-effect-free.
Limit them to validations, NOT data modifications. Defer heavy work to application code or LISTEN/NOTIFY workers.
Always test trigger code in a transaction block. PostgreSQL will reveal 27000 errors early, before code reaches production.
25001 read_only_sql_transaction – happens when DML runs inside a read-only transaction. Switch off read-only mode to fix.
21000 cardinality_violation – occurs when a subquery returns more than one row in a scalar context. Add LIMIT 1 or restructure the query.
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No. PostgreSQL enforces the SQL standard. You must redesign the trigger or defer the action.
Only if the trigger body stops modifying the same table. Statement-level triggers can still violate 27000 when they touch transition tables.
It works for constraint triggers marked DEFERRABLE. Regular triggers still fire immediately and can raise 27000.
Galaxy’s editor highlights recursive DML patterns in trigger bodies and offers AI refactors that move conflicting logic to deferred jobs or separate tables, reducing 27000 incidents.
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