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https://issues.apache.org/jira/browse/HIVE-2812?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Phabricator updated HIVE-2812:
------------------------------
Attachment: HIVE-2812.D1821.1.patch
kevinwilfong requested code review of "HIVE-2812 [jira] Hive multi group by
single reducer optimization fails when aggregation with no keys followed by
query with no aggregations".
Reviewers: JIRA
https://issues.apache.org/jira/browse/HIVE-2812
In multi insert queries, subqueries with aggregations but no group by keys
were being grouped with subqueries without any aggregations. This meant if a
subquery without aggregations came first, the subqueries without group by keys
were not benefitting from the optimization. More imporantly, if a subquery
without group by keys came first, the Semantic Analyzer tried to add group by
operators for queries without group by clauses resulting in an error during
semantic analysis. This patch fixes this by ensuring the two types of
subqueries are grouped separately.
In multi insert queries where one subquery involves an aggregation with no
distinct or group by keys and is followed by a query without any aggregations,
like the following, Hive will attempt to add a group by operator for the query
without aggregations, causing semantic analysis to fail.
FROM src
INSERT OVERWRITE TABLE table1 SELECT count
INSERT OVERWRITE TABLE table2 SELECT key;
TEST PLAN
EMPTY
REVISION DETAIL
https://reviews.facebook.net/D1821
AFFECTED FILES
ql/src/test/results/clientpositive/groupby_multi_single_reducer3.q.out
ql/src/test/queries/clientpositive/groupby_multi_single_reducer3.q
ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java
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> Hive multi group by single reducer optimization fails when aggregation with
> no keys followed by query with no aggregations
> --------------------------------------------------------------------------------------------------------------------------
>
> Key: HIVE-2812
> URL: https://issues.apache.org/jira/browse/HIVE-2812
> Project: Hive
> Issue Type: Bug
> Affects Versions: 0.9.0
> Reporter: Kevin Wilfong
> Assignee: Kevin Wilfong
> Attachments: HIVE-2812.D1821.1.patch
>
>
> In multi insert queries where one subquery involves an aggregation with no
> distinct or group by keys and is followed by a query without any
> aggregations, like the following, Hive will attempt to add a group by
> operator for the query without aggregations, causing semantic analysis to
> fail.
> FROM src
> INSERT OVERWRITE TABLE table1 SELECT count(*)
> INSERT OVERWRITE TABLE table2 SELECT key;
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