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From "Taewoo Kim (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ASTERIXDB-1727) Adding grouping hint breaks the query
Date Fri, 04 Nov 2016 23:57:58 GMT

    [ https://issues.apache.org/jira/browse/ASTERIXDB-1727?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15638111#comment-15638111
] 

Taewoo Kim commented on ASTERIXDB-1727:
---------------------------------------

During the optimization, the given group-by logical operator contains two aggregates in the
subplan. Based on the hash hint, the physical operator for this logical group-by is set as
EXTERNAL_GROUP_BY. However, we don't support multiple aggregates in the EXTERNAL_GROUP_BY
yet. So, we need to set PRE_CLUSTERED_GROUP_BY instead of EXTERNAL_GROUP_BY. 

In short, this query with hash hint by will ignore the hash hint.

> Adding grouping hint breaks the query
> -------------------------------------
>
>                 Key: ASTERIXDB-1727
>                 URL: https://issues.apache.org/jira/browse/ASTERIXDB-1727
>             Project: Apache AsterixDB
>          Issue Type: Bug
>            Reporter: Pouria
>            Assignee: Taewoo Kim
>
> The following query works fine with no hint. Adding a hint to use hash-based group-by
breaks it with the following error:
> {noformat}
> Variable $$43 could not be found in any input schema. [AlgebricksException]
> {noformat}
> Here is the query:
> {noformat}
> let $customer := {{ {"cid" : 1}, {"cid" : 2} }}
> let $orders := {{ 
> 	{"oid": 100, 
> 	"ocid" : 1, 
> 	"priority" : 10,
> 	 "class" : "A",
> 	 "items" : [{"price" : 1000}, { "price" : 2000}]
> 	},
> 	{"oid": 200, 
> 	"ocid" : 2, 
> 	"priority" : 20,
> 	 "class" : "A",
> 	 "items" : [{"price" : 2000}, {"price" : 3000}]
> 	}
> }}
> for $c in $customer
> for $o in $orders
> where
>   $c.cid = $o.ocid 
> for $i in $o.items
> /*+ hash*/
> group by $o_orderid := $o.oid, $o_class := $o.class, $o_priority := $o.priority
>   with $i
> let $price := sum (
>   for $t in $i 
>   return 
>     $t.price
> )
> order by $price desc, $o_class
> return {  
>   "o_orderkey": $o_orderid,
>   "price": $price,
>   "o_class": $o_class,
>   "o_priority": $o_priority 
> }
> {noformat}



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