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https://issues.apache.org/jira/browse/HIVE-15544?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15825491#comment-15825491
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Xuefu Zhang commented on HIVE-15544:
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Re: Can you explain what do you mean by semantic problem at runtime?
Since Hive doesn't know if a subquery will produce a single value, so as you
proposed, Hive fails the query at runtime if it doesn't. This basically pushes
a semantic problem (by relaxing semantic check) to a runtime problem. It seems
so harsh (and probably unacceptable) that a query that has run for hours ends
up with failure.
I didn't read your patch, but let me know if I misunderstood your proposal.
> Support scalar subqueries
> -------------------------
>
> Key: HIVE-15544
> URL: https://issues.apache.org/jira/browse/HIVE-15544
> Project: Hive
> Issue Type: Sub-task
> Components: SQL
> Reporter: Vineet Garg
> Assignee: Vineet Garg
> Labels: sub-query
> Attachments: HIVE-15544.1.patch, HIVE-15544.2.patch,
> HIVE-15544.3.patch
>
>
> Currently HIVE only support IN/EXISTS/NOT IN/NOT EXISTS subqueries. HIVE
> doesn't allow sub-queries such as:
> {code}
> explain select a.ca_state state, count(*) cnt
> from customer_address a
> ,customer c
> ,store_sales s
> ,date_dim d
> ,item i
> where a.ca_address_sk = c.c_current_addr_sk
> and c.c_customer_sk = s.ss_customer_sk
> and s.ss_sold_date_sk = d.d_date_sk
> and s.ss_item_sk = i.i_item_sk
> and d.d_month_seq =
> (select distinct (d_month_seq)
> from date_dim
> where d_year = 2000
> and d_moy = 2 )
> and i.i_current_price > 1.2 *
> (select avg(j.i_current_price)
> from item j
> where j.i_category = i.i_category)
> group by a.ca_state
> having count(*) >= 10
> order by cnt
> limit 100;
> {code}
> We initially plan to support such scalar subqueries in filter i.e. WHERE and
> HAVING
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