public static void foo(RelNode rel) {
// Convert rel tree to JSON.
final RelJsonWriter writer = new RelJsonWriter();
rel.explain(writer);
final String json = writer.asString();
// Find the schema. If there are no tables in the plan, we won't need one.
final RelOptSchema[] schemas = {null};
rel.accept(
new RelShuttleImpl() {
@Override
public RelNode visit(TableAccessRelBase scan) {
schemas[0] = scan.getTable().getRelOptSchema();
return super.visit(scan);
}
});
// Convert JSON back to rel tree.
Frameworks.withPlanner(
new Frameworks.PlannerAction<Object>() {
public Object apply(
RelOptCluster cluster, RelOptSchema relOptSchema, SchemaPlus rootSchema) {
final RelJsonReader reader = new RelJsonReader(cluster, schemas[0], rootSchema);
try {
RelNode x = reader.read(json);
} catch (IOException e) {
throw new RuntimeException(e);
}
return null;
}
});
}
/**
* Converts a relational expression to one that uses a {@link
* net.hydromatic.optiq.impl.StarTable}. The relational expression is already in leaf-join-form,
* per {@link #toLeafJoinForm(org.eigenbase.rel.RelNode)}.
*/
public static RelNode tryUseStar(RelNode rel, final RelOptTable starRelOptTable) {
final StarTable starTable = starRelOptTable.unwrap(StarTable.class);
assert starTable != null;
return rel.accept(
new RelShuttleImpl() {
@Override
public RelNode visit(TableAccessRelBase scan) {
RelOptTable relOptTable = scan.getTable();
final Table table = relOptTable.unwrap(Table.class);
if (table.equals(starTable.tables.get(0))) {
Mappings.TargetMapping mapping =
Mappings.createShiftMapping(
starRelOptTable.getRowType().getFieldCount(),
0,
0,
relOptTable.getRowType().getFieldCount());
return CalcRel.createProject(
new TableAccessRel(scan.getCluster(), starRelOptTable),
Mappings.asList(mapping.inverse()));
}
return scan;
}
@Override
public RelNode visit(JoinRel join) {
for (; ; ) {
RelNode rel = super.visit(join);
if (rel == join || !(rel instanceof JoinRel)) {
return rel;
}
join = (JoinRel) rel;
final RelNode left = join.getLeft();
final RelNode right = join.getRight();
try {
if (left instanceof TableAccessRelBase && right instanceof TableAccessRelBase) {
match(left, null, right, null, join.getCluster());
}
if (isProjectedTable(left) && right instanceof TableAccessRelBase) {
final ProjectRel leftProject = (ProjectRel) left;
match(
leftProject.getChild(),
leftProject.getMapping(),
right,
null,
join.getCluster());
}
if (left instanceof TableAccessRelBase && isProjectedTable(right)) {
final ProjectRel rightProject = (ProjectRel) right;
match(
left,
null,
rightProject.getChild(),
rightProject.getMapping(),
join.getCluster());
}
if (isProjectedTable(left) && isProjectedTable(right)) {
final ProjectRel leftProject = (ProjectRel) left;
final ProjectRel rightProject = (ProjectRel) right;
match(
leftProject.getChild(),
leftProject.getMapping(),
rightProject.getChild(),
rightProject.getMapping(),
join.getCluster());
}
} catch (Util.FoundOne e) {
return (RelNode) e.getNode();
}
}
}
private boolean isProjectedTable(RelNode rel) {
return rel instanceof ProjectRel
&& ((ProjectRel) rel).isMapping()
&& ((ProjectRel) rel).getChild() instanceof TableAccessRelBase;
}
/**
* Throws a {@link org.eigenbase.util.Util.FoundOne} containing a {@link
* org.eigenbase.rel.TableAccessRel} on success. (Yes, an exception for normal operation.)
*/
private void match(
RelNode left,
Mappings.TargetMapping leftMapping,
RelNode right,
Mappings.TargetMapping rightMapping,
RelOptCluster cluster) {
if (leftMapping == null) {
leftMapping = Mappings.createIdentity(left.getRowType().getFieldCount());
}
if (rightMapping == null) {
rightMapping = Mappings.createIdentity(right.getRowType().getFieldCount());
}
final RelOptTable leftRelOptTable = left.getTable();
final Table leftTable = leftRelOptTable.unwrap(Table.class);
final RelOptTable rightRelOptTable = right.getTable();
final Table rightTable = rightRelOptTable.unwrap(Table.class);
if (leftTable instanceof StarTable
&& ((StarTable) leftTable).tables.contains(rightTable)) {
System.out.println("left: " + leftMapping);
System.out.println("right: " + rightMapping);
Mappings.TargetMapping mapping =
Mappings.merge(
leftMapping,
Mappings.offset(
rightMapping,
((StarTable) leftTable).columnOffset(rightTable),
leftRelOptTable.getRowType().getFieldCount()));
throw new Util.FoundOne(
CalcRel.createProject(
new TableAccessRel(cluster, leftRelOptTable),
Mappings.asList(mapping.inverse())));
}
if (rightTable instanceof StarTable
&& ((StarTable) rightTable).tables.contains(leftTable)) {
assert false; // TODO:
Mappings.TargetMapping mapping = Mappings.append(leftMapping, rightMapping);
throw new Util.FoundOne(
CalcRel.createProject(
new TableAccessRel(cluster, rightRelOptTable),
Mappings.asList(mapping.inverse())));
}
}
});
}
