JSONStringsEachRowWithProgress

Description

Differs from JSONEachRow/JSONStringsEachRow in that ClickHouse streams each event as a separate JSON object and also yields progress information. All field values are serialized as strings (including complex types): for example arr is emitted as "arr":"[0,1]", not as a nested JSON array. Scalars are likewise stringified ("num":"42"). The top-level object kinds match JSONEachRowWithProgress (meta, row, progress, totals/min/max, rows_before_limit_at_least, rows_before_aggregation, and top-level exception). Follow that page for the full stream contract: a progress object may arrive before meta; rows_before_limit_at_least is a lower estimate when the query contains LIMIT (not proof rows were dropped); exception is only written on the HTTP path with http_write_exception_in_output_format=1.

Example usage

{"meta":[{"name":"num","type":"UInt8"},{"name":"str","type":"String"},{"name":"arr","type":"Array(UInt8)"}]}
{"row":{"num":"42","str":"hello","arr":"[0,1]"}}
{"row":{"num":"43","str":"hello","arr":"[0,1,2]"}}
{"row":{"num":"44","str":"hello","arr":"[0,1,2,3]"}}
{"progress":{"read_rows":"3","read_bytes":"24","written_rows":"0","written_bytes":"0","total_rows_to_read":"3"}}

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