[GitHub] [druid] jihoonson commented on a change in pull request #10144: Follow-up for RetryQueryRunner fix

[GitBox <gi...@apache.org>]

jihoonson commented on a change in pull request #10144:
URL: https://github.com/apache/druid/pull/10144#discussion_r451256360



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File path: docs/querying/querying.md
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@@ -139,4 +139,5 @@ Possible codes for the *error* field include:
 |`Resource limit exceeded`|The query exceeded a configured resource limit (e.g. groupBy maxResults).|
 |`Unauthorized request.`|The query was denied due to security policy. Either the user was not recognized, or the user was recognized but does not have access to the requested resource.|
 |`Unsupported operation`|The query attempted to perform an unsupported operation. This may occur when using undocumented features or when using an incompletely implemented extension.|
+|`Truncated response context`|The response context is an internal data structure to store intermediate state during query processing. Some of states are collected from query servers (such as historicals or realtime tasks) and merged in the Broker. To send those states to the Broker, the query servers serialize them in the HTTP header and send it together with the stream of intermediate query result. As the max size of an HTTP header is limited to 7 KB in Druid, this error can occur if JSON-serialized response context is larger than the limit.<br/><br/>This error shouldn't happen in most cases. A possible cause of this error can be too many segments moving (for segment balancing) at the time when a query is issued which reads lots of segments. You should be able to see debug logs about missing segments in the historical logs if you are facing this case.|

Review comment:
       👍 




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