Paul Jackson created CALCITE-3101:
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Summary: PushDownJoinConditions is not always a valid
transformation
Key: CALCITE-3101
URL: https://issues.apache.org/jira/browse/CALCITE-3101
Project: Calcite
Issue Type: Bug
Components: core
Affects Versions: 1.16.0
Environment: Java app pointing to Oracle database.
Reporter: Paul Jackson
SqlToRelConverter can create a plan that is invalid when converted back to SQL
in cases where the expression that is pushed to the projection returns a
Boolean. The following example pushes IS NOT NULL to a select. Several SQL
dialects do not support this. Oracle, for example, sees IS NOT NULL as a
condition rather than an expression. It returns a Boolean data type, which is
not supported. Likewise, Microsoft SQL Server does not support IS NOT NULL in a
projection expression.
Steps to reproduce (Oracle) :
DDL:
{{CREATE TABLE "EMP" (}}
{{ "empno" INTEGER PRIMARY KEY NOT NULL,}}
{{ "ename" VARCHAR(100),}}
{{"deptno" INTEGER);}}
Start with this query:
{{SELECT "EMP"."empno", "t"."ename" "ename0"}}
{{FROM "EMP"}}
{{INNER JOIN "EMP" "t"}}
{{ON "EMP"."deptno" = "t"."deptno" AND "t"."ename" IS NOT NULL}}
Parse using SqlToRelConverter.convertQuery()
At his point in the stack trace:
{{org.apache.calcite.plan.RelOptUtil.pushDownJoinConditions(RelOptUtil.java:3222)}}
{{org.apache.calcite.sql2rel.SqlToRelConverter.createJoin(SqlToRelConverter.java:2414)}}
{{org.apache.calcite.sql2rel.SqlToRelConverter.convertFrom(SqlToRelConverter.java:2056)}}
{{org.apache.calcite.sql2rel.SqlToRelConverter.convertSelectImpl(SqlToRelConverter.java:641)}}
{{org.apache.calcite.sql2rel.SqlToRelConverter.convertSelect(SqlToRelConverter.java:622)}}
{{org.apache.calcite.sql2rel.SqlToRelConverter.convertQueryRecursive(SqlToRelConverter.java:3057)}}
{{org.apache.calcite.sql2rel.SqlToRelConverter.convertQuery(SqlToRelConverter.java:558)}}
the RelNode is:
{{LogicalJoin(condition=[AND(=($3, $8), IS NOT NULL($6))], joinType=[inner])}}
{{ JdbcTableScan(table=[[XYZ, EMP]])}}
{{ JdbcTableScan(table=[[XYZ, EMP]])}}
After pushDownJoinConditions the RelNode is:
{{LogicalJoin(condition=[AND(=($3, $8), $10)], joinType=[inner])}}
{{ JdbcTableScan(table=[[XYZ, EMP]])}}
{{ LogicalProject(empno=[$0], ename=[$1], job=[$2], deptno=[$3], etype=[$4],
$f5=[IS NOT NULL($1)])}}
{{ JdbcTableScan(table=[[XYZ, EMP]])}}
Which leads to invalid SQL (ORA-00923: FROM keyword not found where expected) :
{{SELECT "EMP"."empno", "t"."ename" "ename0"}}
{{FROM "XYZ"."EMP"}}
{{INNER JOIN (SELECT "empno", "ename", "job", "deptno", "etype", "ename" IS NOT
NULL "$f5"}}
{{FROM "XYZ"."EMP") "t" ON "EMP"."deptno" = "t"."deptno" AND "t"."$f5"}}
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