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https://issues.apache.org/jira/browse/HIVE-1694?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12927073#action_12927073
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Namit Jain commented on HIVE-1694:
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Had an offline discussion with John just now - I think he is also giving
similar comments, so I will keep it very brief.
One concern is that all the optimizations should be at the operator level, I
mean - this should be treated as just another optimization.
As you mentioned in your presentation correctly, Hive does not support
cost-based optimizer currently, and it will
require all the optimizations to be consolidated in one place to help move to
that model.
We are thinking about moving the group by skews also in the optimizer (instead
of the current approach in
SemanticAnalyzer). Once all the optimizations are in a central place, it will
be much easier to move to costing.
The Harvey Mudd folks currently are not looking at Group By optimizations for
indexing, so, this will be extremely
useful for the whole community.
> Accelerate query execution using indexes
> ----------------------------------------
>
> Key: HIVE-1694
> URL: https://issues.apache.org/jira/browse/HIVE-1694
> Project: Hive
> Issue Type: New Feature
> Components: Indexing, Query Processor
> Affects Versions: 0.7.0
> Reporter: Nikhil Deshpande
> Attachments: demo_q1.hql, demo_q2.hql, HIVE-1694_2010-10-28.diff
>
>
> The index building patch (Hive-417) is checked into trunk, this JIRA issue
> tracks supporting indexes in Hive compiler & execution engine for SELECT
> queries.
> This is in ref. to John's comment at
> https://issues.apache.org/jira/browse/HIVE-417?focusedCommentId=12884869&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#action_12884869
> on creating separate JIRA issue for tracking index usage in optimizer & query
> execution.
> The aim of this effort is to use indexes to accelerate query execution (for
> certain class of queries). E.g.
> - Filters and range scans (already being worked on by He Yongqiang as part of
> HIVE-417?)
> - Joins (index based joins)
> - Group By, Order By and other misc cases
> The proposal is multi-step:
> 1. Building index based operators, compiler and execution engine changes
> 2. Optimizer enhancements (e.g. cost-based optimizer to compare and choose
> between index scans, full table scans etc.)
> This JIRA initially focuses on the first step. This JIRA is expected to hold
> the information about index based plans & operator implementations for above
> mentioned cases.
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