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From "John Sichi (JIRA)" <j...@apache.org>
Subject [jira] Issue Comment Edited: (HIVE-1694) Accelerate query execution using indexes
Date Mon, 01 Nov 2010 18:32:25 GMT

    [ https://issues.apache.org/jira/browse/HIVE-1694?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12927077#action_12927077
] 

John Sichi edited comment on HIVE-1694 at 11/1/10 2:30 PM:
-----------------------------------------------------------

+1 to what Namit said.  Doing the rewrites at the relational algebra Operator level (similar
to the way optimizer transformations such as predicate pushdown already work) will have two
big advantages:

* more general (syntax-independent)

* much easier to maintain (as you noted in your presentation, the SemanticAnalyzer data structures
can be very difficult to analyze and manipulate, whereas the Operator structures are a lot
cleaner)

BTW, thanks for the very clear explanation of the work you've done so far.


      was (Author: jvs):
    +1 to what Namit said.  Doing the rewrites at the relational algebra Operator level (similar
to the way optimizer transformations such as predicate pushdown already work) will have two
big advantages:

* more general (syntax-independent)

* much easier to maintain (as you noted in your presentation, the SemanticAnalyzer data structures
can be very difficult to analyze and manipulate, whereas the Operator tree are a lot cleaner)

BTW, thanks for the very clear explanation of the work you've done so far.

  
> 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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