aggregate_* session settings

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aggregate_function_input_format

• state — Binary string with the serialized state (the default). This is the default behavior where AggregateFunction values are expected as binary data.
• value — The format expects a single value of the argument of the aggregate function, or in the case of multiple arguments, a tuple of them. They will be deserialized using the corresponding IDataType or DataTypeTuple and then aggregated to form the state.
• array — The format expects an Array of values, as described in the value option above. All elements of the array will be aggregated to form the state.

CREATE TABLE example (
    user_id UInt64,
    avg_session_length AggregateFunction(avg, UInt32)
);

INSERT INTO example FORMAT CSV
123,456

INSERT INTO example FORMAT CSV
123,"[456,789,101]"

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aggregate_functions_null_for_empty

• 0 — Disabled.
• 1 — Enabled.

SELECT SUM(-1), MAX(0) FROM system.one WHERE 0;

┌─SUM(-1)─┬─MAX(0)─┐
│       0 │      0 │
└─────────┴────────┘

┌─SUMOrNull(-1)─┬─MAXOrNull(0)─┐
│          NULL │         NULL │
└───────────────┴──────────────┘