[jira] [Commented] (TAJO-838) Improve query planner to utilize index

[ASF GitHub Bot (JIRA)]

    [ 
https://issues.apache.org/jira/browse/TAJO-838?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14227199#comment-14227199
 ] 

ASF GitHub Bot commented on TAJO-838:
-------------------------------------

Github user jihoonson commented on a diff in the pull request:

    https://github.com/apache/tajo/pull/231#discussion_r20977379
  
    --- Diff: 
tajo-core/src/main/java/org/apache/tajo/master/querymaster/QueryMasterTask.java 
---
    @@ -350,9 +351,12 @@ public synchronized void startQuery() {
             LOG.warn("Query already started");
             return;
           }
    +      LOG.info(SessionVars.INDEX_ENABLED.keyname() + " : " + 
queryContext.getBool(SessionVars.INDEX_ENABLED));
           CatalogService catalog = 
getQueryTaskContext().getQueryMasterContext().getWorkerContext().getCatalog();
           LogicalPlanner planner = new LogicalPlanner(catalog);
    -      LogicalOptimizer optimizer = new LogicalOptimizer(systemConf);
    +      LogicalOptimizer optimizer = new LogicalOptimizer(systemConf, 
catalog,
    --- End diff --
    
    Thanks for the variable comment. I'll refactor this part according to your 
comment.


> Improve query planner to utilize index
> --------------------------------------
>
>                 Key: TAJO-838
>                 URL: https://issues.apache.org/jira/browse/TAJO-838
>             Project: Tajo
>          Issue Type: Sub-task
>          Components: planner/optimizer
>            Reporter: Jihoon Son
>            Assignee: Jihoon Son
>            Priority: Minor
>
> Index can improve the query performance when the selectivity of query is high.
> Thus, query planner should decide whether index is used or not for a given 
> query.
> The selectivity can be guessed using statistics.



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