[jira] [Commented] (TRAFODION-2569) Improve handling of index hints

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TRAFODION-2569?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15963249#comment-15963249 ] 

ASF GitHub Bot commented on TRAFODION-2569:
-------------------------------------------

GitHub user zellerh opened a pull request:

    https://github.com/apache/incubator-trafodion/pull/1057

    [TRAFODION-2569] Improve handling of index hints

    Allowing hints in update and delete statements - they apply to the
    scan of the table. Also making sure that heuristics to eliminate
    indexes don't apply to indexes listed in a hint. Excluding the right
    child of an index join when giving priority to plans that satisfy the
    hint. Otherwise, an index join (index - base table) could be chosen
    when the hint lists the base table.
    
    Also removed some unused interfaces:
    - no_log option in grammar, since it made changing the update syntax harder.
      If we decide to implement incremental MVs in the future, we should use
      a better parser or a different syntax for the no log feature.
    - Some obsolete parser rules.
    - Another set of hints in the scan node, in addition to those in the RelExpr.

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/zellerh/incubator-trafodion bug/cses_jan-17

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/incubator-trafodion/pull/1057.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #1057
    
----
commit 7cb964f52202f2283d0dd34975e28af179e785a2
Author: Hans Zeller <hz...@apache.org>
Date:   2017-04-10T17:43:59Z

    [TRAFODION-2569] Improve handling of index hints
    
    Allowing hints in update and delete statements - they apply to the
    scan of the table. Also making sure that heuristics to eliminate
    indexes don't apply to indexes listed in a hint. Excluding the right
    child of an index join when giving priority to plans that satisfy the
    hint. Otherwise, an index join (index - base table) could be chosen
    when the hint lists the base table.
    
    Also removed some unused interfaces:
    - no_log option in grammar, since it made changing the update syntax harder.
      If we decide to implement incremental MVs in the future, we should use
      a better parser or a different syntax for the no log feature.
    - Some obsolete parser rules.
    - Another set of hints in the scan node, in addition to those in the RelExpr.

----


> Improve handling of index hints
> -------------------------------
>
>                 Key: TRAFODION-2569
>                 URL: https://issues.apache.org/jira/browse/TRAFODION-2569
>             Project: Apache Trafodion
>          Issue Type: Improvement
>          Components: sql-cmp
>    Affects Versions: 2.0-incubating
>            Reporter: Hans Zeller
>            Assignee: Hans Zeller
>             Fix For: 2.2-incubating
>
>
> We allow index hints of this form:
> select ... from table1 <<+index TRAFODION.SCH.IX1>> ...
> In many cases, the compiler does not choose the index specified in the hint, however. A few improvements I am planning to do, if I can pull it off:
> * if we need an index join, make sure we get it using this index
> * allow hints in update statements
> * bind the names in the hint, so they don't have to be specified as upper-case 3-part names.
> * issue a warning if the table name in the index does not specify an index



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