Github user jinfengni commented on the issue: https://github.com/apache/drill/pull/819 Regarding Paul's suggestion of using sampling (either 1st batch, or `n` batches), if the sampled length is returned to client as metadata for query result set, it could cause quite big problems for client. If the sampled max length is 5, client expects to see varchar up to 5 chars. If a new batch arrives with varchar(10), it would either crash the client, or make the client show incorrect result. AFAIK, that's exactly what happened when Sean was working on 'LIMIT 0' optimization, and if there is an inconsistency of the type returned between 'LIMIT 0' and one returned from a regular query.
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