[jira] [Commented] (HIVE-2925) Support non-MR fetching for simple queries with select/limit/filter operations only

["Phabricator (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-2925?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13274782#comment-13274782 ] 

Phabricator commented on HIVE-2925:
-----------------------------------

njain has commented on the revision "HIVE-2925 [jira] Support non-MR fetching for simple queries with select/limit/filter operations only".

INLINE COMMENTS
  ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java:6964 Do you want to push the all these checks also in isSimpleSelectQuery ?
  ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java:6976 empty where clause should be checked in isSelectStarOnly ?
  ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java:6974 No need to initialize work if 1 of the below 2 conds is not true
  ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java:7030 I am missing something here: can the code be refactored so that this check happens only
  at the beginning ?

  I know, the code is not clean, but can you do some cleanup here ?
  ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java:7346 This is due to legacy bad code - now that you are cleaning it, it would be much simpler
  if all this was moved to a new optimizer step (including select star optimizations).

  That would simplify the code a lot, and also makes it easier to disable this optimization.
  ql/src/java/org/apache/hadoop/hive/ql/exec/FetchTask.java:135 Do you need this ? Can you use FileSinkOperator ?

REVISION DETAIL
  https://reviews.facebook.net/D2607

To: JIRA, navis
Cc: njain

                
> Support non-MR fetching for simple queries with select/limit/filter operations only
> -----------------------------------------------------------------------------------
>
>                 Key: HIVE-2925
>                 URL: https://issues.apache.org/jira/browse/HIVE-2925
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Navis
>            Assignee: Navis
>            Priority: Trivial
>         Attachments: HIVE-2925.D2607.1.patch, HIVE-2925.D2607.2.patch, HIVE-2925.D2607.3.patch, HIVE-2925.D2607.4.patch
>
>
> It's trivial but frequently asked by end-users. Currently, select queries with simple conditions or limit should run MR job which takes some time especially for big tables, making the people irritated.
> For that kind of simple queries, using fetch task would make them happy.

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