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https://issues.apache.org/jira/browse/HIVE-3633?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13506732#comment-13506732
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Kevin Wilfong commented on HIVE-3633:
-------------------------------------
Added a bunch of comments on the diff. It's mostly minor things and questions
to make sure I understand the logic.
> sort-merge join does not work with sub-queries
> ----------------------------------------------
>
> Key: HIVE-3633
> URL: https://issues.apache.org/jira/browse/HIVE-3633
> Project: Hive
> Issue Type: Improvement
> Components: Query Processor
> Reporter: Namit Jain
> Assignee: Namit Jain
> Attachments: hive.3633.1.patch, hive.3633.2.patch, hive.3633.3.patch,
> hive.3633.4.patch, hive.3633.5.patch, hive.3633.6.patch, hive.3633.7.patch
>
>
> Consider the following query:
> create table smb_bucket_1(key int, value string) CLUSTERED BY (key) SORTED BY
> (key) INTO 6 BUCKETS STORED AS TEXTFILE;
> create table smb_bucket_2(key int, value string) CLUSTERED BY (key) SORTED BY
> (key) INTO 6 BUCKETS STORED AS TEXTFILE;
> -- load the above tables
> set hive.optimize.bucketmapjoin = true;
> set hive.optimize.bucketmapjoin.sortedmerge = true;
> set hive.input.format =
> org.apache.hadoop.hive.ql.io.BucketizedHiveInputFormat;
> explain
> select count(*) from
> (
> select /*+mapjoin(a)*/ a.key as key1, b.key as key2, a.value as value1,
> b.value as value2
> from smb_bucket_1 a join smb_bucket_2 b on a.key = b.key)
> subq;
> The above query does not use sort-merge join. This would be very useful as we
> automatically convert the queries to use sorting and bucketing properties for
> join.
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