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From "Zheng Shao (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-261) union all query hangs
Date Tue, 03 Feb 2009 01:29:59 GMT

    [ https://issues.apache.org/jira/browse/HIVE-261?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12669835#action_12669835
] 

Zheng Shao commented on HIVE-261:
---------------------------------

Antlr does not put the code in @after in every return statement.

{code}
    ./build/ql/gen-java/org/apache/hadoop/hive/ql/parse/HiveParser.java

    public final explainStatement_return explainStatement() throws RecognitionException {
        explainStatement_return retval = new explainStatement_return();
        retval.start = input.LT(1);

        CommonTree root_0 = null;

        Token isExtended=null;
        Token KW_EXPLAIN5=null;
        execStatement_return execStatement6 = null;


        CommonTree isExtended_tree=null;
        CommonTree KW_EXPLAIN5_tree=null;
        RewriteRuleTokenStream stream_KW_EXTENDED=new RewriteRuleTokenStream(adaptor,"token
KW_EXTENDED");
        RewriteRuleTokenStream stream_KW_EXPLAIN=new RewriteRuleTokenStream(adaptor,"token
KW_EXPLAIN");
        RewriteRuleSubtreeStream stream_execStatement=new RewriteRuleSubtreeStream(adaptor,"rule
execStatement");
         System.out.println("msgs size=" + msgs.size() + " explain statement"); msgs.push("explain
statement");
        try {
            // /data/users/zshao/sync/apache-trunk-HIVE-261/ql/src/java/org/apache/hadoop/hive/ql/parse/Hive.g:157:2:
( KW_EXPLAIN (isExtended= KW_EXTENDED )? execStatement -> ^( TOK_EXPLAI\
N execStatement ( $isExtended)? ) )
            // /data/users/zshao/sync/apache-trunk-HIVE-261/ql/src/java/org/apache/hadoop/hive/ql/parse/Hive.g:157:4:
KW_EXPLAIN (isExtended= KW_EXTENDED )? execStatement
            {
            KW_EXPLAIN5=(Token)input.LT(1);
            match(input,KW_EXPLAIN,FOLLOW_KW_EXPLAIN_in_explainStatement448); if (failed)
return retval;
            if ( backtracking==0 ) stream_KW_EXPLAIN.add(KW_EXPLAIN5);

            // /data/users/zshao/sync/apache-trunk-HIVE-261/ql/src/java/org/apache/hadoop/hive/ql/parse/Hive.g:157:15:
(isExtended= KW_EXTENDED )?
            int alt2=2;
            int LA2_0 = input.LA(1);

{code}


> union all query hangs
> ---------------------
>
>                 Key: HIVE-261
>                 URL: https://issues.apache.org/jira/browse/HIVE-261
>             Project: Hadoop Hive
>          Issue Type: Bug
>          Components: Query Processor
>            Reporter: Hao Liu
>
> we have this query:
> SELECT a.u, b.id FROM (
>  SELECT a1.u, a1.id as id FROM t_1 a1 WHERE a1.date = '2009-01-01' UNION ALL
>  SELECT a2.u, a2.id as id FROM t_2 a2 WHERE a2.date = '2009-01-01' UNION ALL
>  ...
>  SELECT aN.u, aN.id as id FROM t_N an WHERE aN.date = '2009-01-01'
> ) a 
> JOIN t b ON a.id = b.id WHERE b.date='2009-01-01' 
> GROUP BY a.u, b.id
> When we union more than 20 tables, the query will hang. It looks like something wrong
in the compiler.

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