[IMPALA-9414] Support the Expect: 100-continue http header

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 3.4.0
• Component/s: Clients
• Epic Color: ghx-label-10
• Assignee: Thomas Tauber-Marshall
• Reporter: Thomas Tauber-Marshall
• Created: 21/Feb/20 22:04
• Updated: 16/Mar/20 17:29
• Resolved: 16/Mar/20 17:29

Description

The "Expect: 100-continue" http header allows http clients to send only the headers for their request, get a confirmation back from the server that the headers are valid, and only then send the body of the request, avoiding the overhead of sending large requests that will ultimately fail.

This would be useful for Impala in situations like submitting a large query to a Kerberos-secured Impala where requests are proxied through Apache Knox, where it would allow us to verify the credentials before the query text is send over the network.

We should implement support for this both in the hs2 http server and in any clients.