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https://issues.apache.org/jira/browse/DRILL-3929?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14999045#comment-14999045
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Aman Sinha commented on DRILL-3929:
-----------------------------------
Thanks for your feedback [~julianhyde] and [~jamestaylor]. Let me respond to
Julian's feedback first. I think it really comes down to requirement.
Are we trying to build an optimizer/execution model for generalized index/MV
selection where suppose the same column may appear in multiple indexes/MVs and
the goal is to find the best match based on costing ? RDBMs's have done a lot
of work on this (a good paper that combines both MV and Indexes is:
http://www.vldb.org/conf/2000/P496.pdf). This assumes appropriate statistics
exist.
Or, are we trying to leverage the full power of external indices such as
Elasticsearch etc. in which users may create an index offline (i.e without
Drill's involvement) but then use Drill to query the table (not the index
directly). I was more focused on this scenario. Here, the choice is just two:
full table scan or index lookup followed by join-back to table, since the
index-specific optimization is left upto Elasticsearch. I understand your
concern that this won't meet the previously mentioned requirement. I will
discuss this with some more folks but my I think my proposal should not
preclude from trying to satisfy the first requirement in the future.
> Support the ability to query database tables using external indices
> ------------------------------------------------------------------------------
>
> Key: DRILL-3929
> URL: https://issues.apache.org/jira/browse/DRILL-3929
> Project: Apache Drill
> Issue Type: New Feature
> Components: Execution - Relational Operators, Query Planning &
> Optimization
> Reporter: Aman Sinha
> Assignee: Aman Sinha
>
> This is a placeholder for adding support in Drill to query database tables
> using external indices. I will add more details about the use case and a
> preliminary design proposal.
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