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Posted to issues@impala.apache.org by "Dimitris Tsirogiannis (JIRA)" <ji...@apache.org> on 2018/04/12 20:54:00 UTC

[jira] [Created] (IMPALA-6843) Responses to prioritizedLoad() requests are returned directly and not via the statestore

Dimitris Tsirogiannis created IMPALA-6843:
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             Summary: Responses to prioritizedLoad() requests are returned directly and not via the statestore
                 Key: IMPALA-6843
                 URL: https://issues.apache.org/jira/browse/IMPALA-6843
             Project: IMPALA
          Issue Type: Improvement
          Components: Catalog
    Affects Versions: Impala 2.11.0
            Reporter: Dimitris Tsirogiannis
            Assignee: Dimitris Tsirogiannis


Currently, when a statement (e.g. SELECT) needs to access some unloaded tables, it issues a prioritizedLoad() request to the catalog. The catalog loads the table metadata but does not respond directly to the coordinator that issued the request. Instead, the metadata for the newly loaded tables are broadcast via the statestore. The problem with this approach is that the latency of the response may vary significantly and may depend on the latencies of other unrelated metadata operations (e.g. REFRESH) that happen to be in the same topic update.

The response to a prioritizedLoad() request should come directly to the issuing coordinator. Other coordinators will receive the metadata of the newly loaded table via the statestore. 



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