Chun Chang created DRILL-2010: --------------------------------- Summary: merge join returns wrong number of rows with large dataset Key: DRILL-2010 URL: https://issues.apache.org/jira/browse/DRILL-2010 Project: Apache Drill Issue Type: Bug Components: Execution - Operators Affects Versions: 0.8.0 Reporter: Chun Chang Assignee: Chris Westin
#Mon Jan 12 18:19:31 EST 2015 git.commit.id.abbrev=5b012bf When data set is big enough (like larger than one batch size), merge join will not returns the correct number of rows. Hash join returns the correct number of rows. Data can be downloaded from: https://s3.amazonaws.com/apache-drill/files/complex100k.json.gz With this dataset, the following query should return 10,000,000. {code} 0: jdbc:drill:schema=dfs.drillTestDirComplexJ> alter session set `planner.enable_mergejoin` = true; +------------+------------+ | ok | summary | +------------+------------+ | true | planner.enable_mergejoin updated. | +------------+------------+ 1 row selected (0.024 seconds) 0: jdbc:drill:schema=dfs.drillTestDirComplexJ> alter session set `planner.enable_hashjoin` = false; +------------+------------+ | ok | summary | +------------+------------+ | true | planner.enable_hashjoin updated. | +------------+------------+ 1 row selected (0.024 seconds) 0: jdbc:drill:schema=dfs.drillTestDirComplexJ> select count(a.id) from `complex100k.json` a inner join `complex100k.json` b on a.gbyi=b.gbyi; +------------+ | EXPR$0 | +------------+ | 9046760 | +------------+ 1 row selected (6.205 seconds) 0: jdbc:drill:schema=dfs.drillTestDirComplexJ> alter session set `planner.enable_mergejoin` = false; +------------+------------+ | ok | summary | +------------+------------+ | true | planner.enable_mergejoin updated. | +------------+------------+ 1 row selected (0.026 seconds) 0: jdbc:drill:schema=dfs.drillTestDirComplexJ> alter session set `planner.enable_hashjoin` = true; +------------+------------+ | ok | summary | +------------+------------+ | true | planner.enable_hashjoin updated. | +------------+------------+ 1 row selected (0.024 seconds) 0: jdbc:drill:schema=dfs.drillTestDirComplexJ> select count(a.id) from `complex100k.json` a inner join `complex100k.json` b on a.gbyi=b.gbyi; +------------+ | EXPR$0 | +------------+ | 10000000 | +------------+ 1 row selected (4.453 seconds) {code} With smaller dataset, both merge and hash join returns the same correct number. physical plan for merge join: {code} 0: jdbc:drill:schema=dfs.drillTestDirComplexJ> explain plan for select count(a.id) from `complex100k.json` a inner join `complex100k.json` b on a.gbyi=b.gbyi; +------------+------------+ | text | json | +------------+------------+ | 00-00 Screen 00-01 StreamAgg(group=[{}], EXPR$0=[COUNT($0)]) 00-02 Project(id=[$1]) 00-03 MergeJoin(condition=[=($0, $2)], joinType=[inner]) 00-05 SelectionVectorRemover 00-07 Sort(sort0=[$0], dir0=[ASC]) 00-09 Scan(groupscan=[EasyGroupScan [selectionRoot=/drill/testdata/complex_type/json/complex100k.json, numFiles=1, columns=[`gbyi`, `id`], files=[maprfs:/drill/testdata/complex_type/json/complex100k.json]]]) 00-04 Project(gbyi0=[$0]) 00-06 SelectionVectorRemover 00-08 Sort(sort0=[$0], dir0=[ASC]) 00-10 Scan(groupscan=[EasyGroupScan [selectionRoot=/drill/testdata/complex_type/json/complex100k.json, numFiles=1, columns=[`gbyi`], files=[maprfs:/drill/testdata/complex_type/json/complex100k.json]]]) {code} -- This message was sent by Atlassian JIRA (v6.3.4#6332)