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From "He Yongqiang (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HIVE-460) Improve ColumnPruner to prune more aggressively and keep column information for input tables
Date Fri, 29 May 2009 14:48:47 GMT

     [ https://issues.apache.org/jira/browse/HIVE-460?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

He Yongqiang updated HIVE-460:
------------------------------

    Attachment: hive-460-2009-05-29-noaliasallowed.patch

hive-460-2009-05-29-noaliasallowed.patch is not a finished version and it still has errors.
The major issue is that it does not allow alias.
For example:
{noformat}
SELECT kv1.key, sum(substr(kv1.value,5)) GROUP BY kv1.key LIMIT 5
{noformat}
works well. But 
{noformat}
SELECT kv1.key as key_alias, sum(substr(kv1.value,5)) GROUP BY key_alias LIMIT 5
{noformat}
even can not pass the parser.

Another error example is 
{noformat}
SELECT src1.key as k1, src1.value as v1, src2.key as k2, src2.value as v2 FROM  
                 (SELECT * FROM kv1 WHERE kv1.key < 10) src1 "
	        JOIN (SELECT * FROM kv1 WHERE kv1.key < 10) src2;
{noformat}
works well, but the one with a sort clause 
{noformat}
SELECT src1.key as k1, src1.value as v1, src2.key as k2, src2.value as v2 FROM  
                 (SELECT * FROM kv1 WHERE kv1.key < 10) src1 "
	        JOIN (SELECT * FROM kv1 WHERE kv1.key < 10) src2 sort by k1,v1,k2,v2;
{noformat}
either can not pass the parser.

I am still trying to figure out why these errors are caused and how to fix them. And really
appreciate some input.

BTW, with this patch, explain ... now will give  'meaningful names', but i don't know whether
they are ok. 

> Improve ColumnPruner to prune more aggressively and keep column information for input
tables
> --------------------------------------------------------------------------------------------
>
>                 Key: HIVE-460
>                 URL: https://issues.apache.org/jira/browse/HIVE-460
>             Project: Hadoop Hive
>          Issue Type: Improvement
>          Components: Query Processor
>    Affects Versions: 0.4.0
>            Reporter: Zheng Shao
>            Assignee: He Yongqiang
>         Attachments: hive-460-2009-05-29-noaliasallowed.patch, HIVE-460.1.patch
>
>
> This is required for column-based table format.

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