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https://issues.apache.org/jira/browse/HIVE-13257?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15190491#comment-15190491
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Ashutosh Chauhan commented on HIVE-13257:
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I have done some digging into this and following is what I have found:
Consider:
select col1, sum(col2) from t group by 1;
There are multiple ways on how above can be interpreted. When I read the
standard, AFAICT constant literal is not allowed in group by expression, so
this should throw an error. However, testing this on different DBs I found
different behavior.
Oracle & SQL server throws error for this. However, MySQL & Postgres assumes 1
in gby clause refers to position 1 in select list, so they translate this
effectively into:
select col1, sum(col2) from t group by col1;
Another interpretation for this is assume its group by on constant, meaning
there is one group for full table.
Hive of course has a config variable using which you can get either behavior
meaning different result set with different value of config variable.
Other variant for this is:
select sum(col2) from t group by 1;
MySQL & Postgres throws error for this consistent with their above
interpretation. SQL Server also throws error for this. However, Oracle
magically interprets this as group by on constant.
Yet another variant:
select 1 from t group by 1;
For this one MySQL, Postgres & Oracle can execute the query. SQL Server throws
error.
So, it seems only SQL Server is compliant with standard and other DBs do
different things depending on context.
I am wondering whether Hive should change its default behavior being consistent
with standard and start throwing exception whenever there it encounters a
constant literal in group by expression. Of course, their will be a config to
get back old behavior. Thoughts?
> GroupBy with column alias does not support AVG
> ----------------------------------------------
>
> Key: HIVE-13257
> URL: https://issues.apache.org/jira/browse/HIVE-13257
> Project: Hive
> Issue Type: Bug
> Affects Versions: 2.1.0
> Reporter: Prasanth Jayachandran
>
> For the following query, with hive.groupby.orderby.position.alias set to true
> {code:title=Query}
> SELECT Avg(`t0`.`x_measure__0`) AS `avg_calculation_270497503505567749_ok`
> FROM (SELECT `store_sales`.`ss_ticket_number` AS `ss_ticket_number`,
> Sum(`store_sales`.`ss_net_paid`) AS `x_measure__0`
> FROM `store_sales` `store_sales`
> JOIN `item` `item`
> ON ( `store_sales`.`ss_item_sk` = `item`.`i_item_sk` )
> GROUP BY `store_sales`.`ss_ticket_number`) `t0`
> GROUP BY 1
> HAVING ( Count(1) > 0 );
> {code}
> it throws the following exception
> {code:title=Exception}
> FAILED: SemanticException [Error 10128]: Line 2:7 Not yet supported place for
> UDAF 'Avg’
> {code}
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