PostgreSQL Error - 2203D too_many_json_array_elements error explained

What is the too_many_json_array_elements error?

PostgreSQL returns SQLSTATE 2203D with the message “too many JSON array elements” when it processes a JSON or JSONB value that contains more array elements than the server permits. The default limit is one million elements in PostgreSQL 16 and later.

The limit protects the database from excessive memory use or denial-of-service attacks.

Any function that parses or builds a JSON array - such as jsonb_agg, to_jsonb, json_array_elements, or COPY - can trigger the exception.

What Causes This Error?

Parsing an oversized JSON payload during INSERT, UPDATE, or COPY quickly exceeds jsonb.max_array_elements and raises the error before the write completes.

Aggregating many rows with jsonb_agg or json_agg can silently build a huge array that crosses the threshold at runtime, aborting the query.

Receiving API data stored as a single row of JSONB often fails if clients send unbounded arrays of events, IDs, or metrics.

How to Fix too_many_json_array_elements

First, inspect the incoming JSON to confirm the element count.

If it legitimately needs to be that large, raise the limit:

ALTER SYSTEM SET jsonb.max_array_elements = 2000000; -- superuser only
SELECT pg_reload_conf();

For session-level tuning during ETL or maintenance, use:

SET LOCAL jsonb.max_array_elements = 2000000;

If the array should be smaller, split it into multiple rows or store it as JSON Lines (one object per line) instead of a single massive array.

Common Scenarios and Solutions

Bulk loading analytics events often hits the cap.

Break the array into daily partitions and insert with COPY FROM STDIN.

jsonb_agg in reporting queries may explode in size. Replace with a LIMIT clause, windowed aggregation, or stream results to the client.

Best Practices to Avoid This Error

Validate payload size in application code before sending it to PostgreSQL.

Reject or paginate any array near one million elements.

Set reasonable jsonb.max_array_elements, jsonb.max_object_members, and jsonb.max_nesting_depth based on workload, then monitor pg_log for early warnings.

Related Errors and Solutions

too_many_json_object_members (2203E) - raised when a JSON object has too many keys. Fix by increasing jsonb.max_object_members or reducing object size.

too_deep_json_nesting (2203F) - occurs when nested JSON exceeds the depth limit. Flatten the structure or raise jsonb.max_nesting_depth.

invalid_json_text (22032) - indicates malformed JSON. Validate and correct the source string.

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