[CALCITE-714] When de-correlating, push join condition into subquery

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.1.0-incubating
• Fix Version/s: 1.4.0-incubating
• Assignee: Aman Sinha
• Reporter: Aman Sinha
• Created: 05/May/15 21:11
• Updated: 01/Sep/15 03:02
• Resolved: 24/Jul/15 09:16

Description

When decorrelating a scalar aggregate subquery, we push copies of the tables from the outer query block into the subquery but don't push the join condition, thereby creating a cartesian join. This seems to be a regression.

Query:

select count(*) 
    from dfs.`/Users/asinha/data/tpch-sf1/nation` n, dfs.`/Users/asinha/data/tpch-sf1/orders` o 
         where n.n_nationkey = o.o_orderkey 
         and n.n_nationkey > (select avg(ps.ps_suppkey) from dfs.`/Users/asinha/data/tpch-sf1/partsupp` ps
                               where n.n_regionkey = ps.ps_partkey);

Here's the plan on an earlier version of Calcite (I am not sure of the version number but it was before the decorrelation refactoring), Note the join between nation and orders at the leaf level has a equi-join condition.

 
AggregateRel(group=[{}], EXPR$0=[COUNT()])
  ProjectRel($f0=[$0])
    ProjectRel($f0=[0])
      FilterRel(condition=[>($1, $5)])
        ProjectRel(*=[$0], n_nationkey=[$1], n_regionkey=[$2], *0=[$3], o_orderkey=[$4], EXPR$0=[$6])
          JoinRel(condition=[=($2, $5)], joinType=[left])
            JoinRel(condition=[=($1, $4)], joinType=[inner])
              EnumerableTableAccessRel(table=[[dfs, /Users/asinha/data/tpch-sf1/nation]])
              EnumerableTableAccessRel(table=[[dfs, /Users/asinha/data/tpch-sf1/orders]])
            AggregateRel(group=[{0}], EXPR$0=[AVG($1)])
              ProjectRel($f0=[$1], ps_suppkey=[$0])
                ProjectRel(ps_suppkey=[$2], $f0=[$3])
                  FilterRel(condition=[=($3, $1)])
                    JoinRel(condition=[true], joinType=[inner])
                      EnumerableTableAccessRel(table=[[dfs, /Users/asinha/data/tpch-sf1/partsupp]])
                      AggregateRel(group=[{0}])
                        ProjectRel($f0=[$2])
                          JoinRel(condition=[=($1, $4)], joinType=[inner])
                            EnumerableTableAccessRel(table=[[dfs, /Users/asinha/data/tpch-sf1/nation]])
                            EnumerableTableAccessRel(table=[[dfs, /Users/asinha/data/tpch-sf1/orders]])

Here's the new plan (I am on version 1.1.0 but I think the plan has not changed in the latest version). Note the join between nation and orders at the leaf level does not have any join condition.

LogicalAggregate(group=[{}], EXPR$0=[COUNT()])
  LogicalProject($f0=[$0])
    LogicalProject($f0=[0])
      LogicalFilter(condition=[AND(=($1, $4), >($1, $5))])
        LogicalProject(*=[$0], n_nationkey=[$1], n_regionkey=[$2], *0=[$3], o_orderkey=[$4], EXPR$0=[$6])
          LogicalJoin(condition=[=($2, $5)], joinType=[left])
            LogicalJoin(condition=[true], joinType=[inner])
              EnumerableTableScan(table=[[dfs, /Users/asinha/data/tpch-sf1/nation]])
              EnumerableTableScan(table=[[dfs, /Users/asinha/data/tpch-sf1/orders]])
            LogicalAggregate(group=[{0}], EXPR$0=[AVG($1)])
              LogicalProject(n_regionkey=[$1], ps_suppkey=[$0])
                LogicalProject(ps_suppkey=[$2], n_regionkey=[$3])
                  LogicalFilter(condition=[=($3, $1)])
                    LogicalJoin(condition=[true], joinType=[inner])
                      EnumerableTableScan(table=[[dfs, /Users/asinha/data/tpch-sf1/partsupp]])
                      LogicalAggregate(group=[{0}])
                        LogicalProject(n_regionkey=[$2])
                          LogicalJoin(condition=[true], joinType=[inner])
                            EnumerableTableScan(table=[[dfs, /Users/asinha/data/tpch-sf1/nation]])
                            EnumerableTableScan(table=[[dfs, /Users/asinha/data/tpch-sf1/orders]])

Issue Links

• is depended upon by: CALCITE-769 FilterProjectTransposeRule needs to avoid filter being pushed down if there is "correlating variable" in the condition