[jira] [Created] (HIVE-20006) materializations invalidation cache work with multiple active remote metastores

["Jesus Camacho Rodriguez (JIRA)" <ji...@apache.org>]

Jesus Camacho Rodriguez created HIVE-20006:
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             Summary: materializations invalidation cache work with multiple active remote metastores
                 Key: HIVE-20006
                 URL: https://issues.apache.org/jira/browse/HIVE-20006
             Project: Hive
          Issue Type: Improvement
          Components: Materialized views
    Affects Versions: 3.0.0
            Reporter: Jesus Camacho Rodriguez
            Assignee: Jesus Camacho Rodriguez
         Attachments: HIVE-19027.01.patch, HIVE-19027.02.patch, HIVE-19027.03.patch, HIVE-19027.04.patch

The main points:
 - Only MVs stored in transactional tables can have a time window value of 0. Those are the only MVs that can be guaranteed to not be outdated when a query is executed, if we use custom storage handlers to store the materialized view, we cannot make any promises.
 - For MVs that +cannot be outdated+, we do not check the metastore. Instead, comparison is based on valid write id lists.
 - For MVs that +can be outdated+, we still rely on the invalidation cache.
 ** The window for valid outdated MVs can be specified in intervals of 1 minute (less than that, it is difficult to have any guarantees about whether the MV is actually outdated by less than a minute or not).
 ** The async loading is done every interval / 2 (or probably better, we can make it configurable).



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