[
https://issues.apache.org/jira/browse/CALCITE-3101?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16851629#comment-16851629
]
Julian Hyde commented on CALCITE-3101:
--------------------------------------
[~laurent], I agree, but whether we transform the {{SqlNode}} tree or just
control the SQL that is generated from it is a just a matter of tactics. Note
that {{SqlDialect}} sometimes helps with the former (e.g.
{{SqlDialect.emulateNullDirection}} returns a transformed {{SqlNode}}).
Anyway, it's safe to say that we will need a new method in SqlDialect:
{{boolean supportsBooleanInSelect()}}.
What do folks feel would be the best SQL to generate? I think that encoding the
{{BOOLEAN}} as an {{INTEGER}} would not be too bad:
{code:java}
SELECT "EMP"."empno", "t"."ename" "ename0"
FROM "XYZ"."EMP"
INNER JOIN (SELECT "empno", "ename", "job", "deptno", "etype",
CASE WHEN "ename" IS NOT NULL THEN 1 ELSE 0 END "$f5"
FROM "XYZ"."EMP") "t" ON "EMP"."deptno" = "t"."deptno" AND "t"."$f5"{code}
> 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
> Priority: Major
>
> 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:
> {code}CREATE TABLE "EMP" (
> "empno" INTEGER PRIMARY KEY NOT NULL,
> "ename" VARCHAR(100),
> "deptno" INTEGER);{code}
> Start with this query:
> {code}SELECT "EMP"."empno", "t"."ename" "ename0"
> FROM "EMP"
> INNER JOIN "EMP" "t"
> ON "EMP"."deptno" = "t"."deptno" AND "t"."ename" IS NOT NULL{code}
> Parse using {{SqlToRelConverter.convertQuery()}}. At this point in the stack
> trace:
> {noformat}
> 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)
> {noformat}
> the {{RelNode}} is:
> {noformat}
> LogicalJoin(condition=[AND(=($3, $8), IS NOT NULL($6))], joinType=[inner])
> JdbcTableScan(table=[[XYZ, EMP]])
> JdbcTableScan(table=[[XYZ, EMP]])
> {noformat}
> After {{pushDownJoinConditions}} the {{RelNode}} is:
> {noformat}
> 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($1)])
> JdbcTableScan(table=[[XYZ, EMP]])
> {noformat}
> Which leads to invalid SQL ("ORA-00923: FROM keyword not found where
> expected"):
> {code}
> SELECT "EMP"."empno", "t"."ename" "ename0"
> FROM "XYZ"."EMP"
> INNER JOIN (SELECT "empno", "ename", "job", "deptno", "etype", "ename" IS NOT
> NULL "$f5"
> FROM "XYZ"."EMP") "t" ON "EMP"."deptno" = "t"."deptno" AND "t"."$f5"
> {code}
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
