PostgreSQL throws duplicate_json_object_key_value when the same key appears twice in a JSON object, stopping the query.
duplicate_json_object_key_value appears when PostgreSQL scans a JSON value and finds two identical keys in the same object. Remove or rename the duplicate key, or cast to jsonb which keeps the last key, then rerun the statement to fix the issue.
duplicate_json_object_key_value
PostgreSQL raises SQLSTATE 22030 – duplicate_json_object_key_value – whenever it parses a JSON object that contains two keys with identical names. The parser treats this as invalid JSON, aborts the statement, and returns the error.
The error can surface in INSERT, UPDATE, COPY, function arguments, or JSON operators.
Because standard JSON forbids duplicate keys, PostgreSQL rejects the value to protect data integrity and predictable query results.
Duplicate property names inside a JSON literal such as '{"id":1, "id":2}' are the direct trigger. The second key collides with the first, violating JSON rules enforced by PostgreSQL.
Applications that build JSON by string concatenation often inject a second key unintentionally.
ETL jobs that merge JSON blobs, or API payloads that allow overriding fields, also produce duplicates.
Validate the JSON string and eliminate duplicate keys before sending it to PostgreSQL. Use jsonb data type if you prefer the last key to win silently because jsonb deduplicates on ingest.
When the source is a table column, run CHECK constraints or a temporary SELECT ...
WHERE json_typeof() IS NOT NULL to locate offending rows, delete or patch them, and retry the operation.
INSERT failure: Clean the JSON payload in the application layer or wrap it with jsonb_build_object() to guarantee unique keys.
UPDATE joining JSON fragments: Use jsonb_merge_patch() or jsonb_set() that overwrite duplicates deterministically.
Always construct JSON with PostgreSQL native functions like to_jsonb(), jsonb_build_object(), or Galaxy's AI copilot snippets.
These functions ensure key uniqueness.
Add a CHECK constraint using jsonb_typeof(col) IS NOT NULL AND col::jsonb = col::jsonb to detect invalid JSON early. Monitor error logs for SQLSTATE 22030 to catch regressions.
invalid_json_text: Raised when JSON is malformed at syntax level – fix by correcting brackets or quotes.
string_data_right_truncation: Can appear if a JSON string exceeds column length – migrate to text or jsonb column types.
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Yes. jsonb silently keeps the last duplicate key so the error never appears. Cast to jsonb when this behavior is acceptable.
All supported versions from 9.4 onward enforce duplicate key checks for the json data type.
Galaxy's AI copilot suggests jsonb_build_object snippets and highlights SQLSTATE 22030 in the editor, making duplicates easy to spot before execution.
jsonb adds a small ingestion overhead but enables indexing, making reads faster. Evaluate workload before switching.
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