public Boolean areColumnsUnique(ProjectRelBase rel, BitSet columns, boolean ignoreNulls) {
// ProjectRel maps a set of rows to a different set;
// Without knowledge of the mapping function(whether it
// preserves uniqueness), it is only safe to derive uniqueness
// info from the child of a project when the mapping is f(a) => a.
//
// Also need to map the input column set to the corresponding child
// references
List<RexNode> projExprs = rel.getProjects();
BitSet childColumns = new BitSet();
for (int bit : BitSets.toIter(columns)) {
RexNode projExpr = projExprs.get(bit);
if (projExpr instanceof RexInputRef) {
childColumns.set(((RexInputRef) projExpr).getIndex());
} else if (projExpr instanceof RexCall && ignoreNulls) {
// If the expression is a cast such that the types are the same
// except for the nullability, then if we're ignoring nulls,
// it doesn't matter whether the underlying column reference
// is nullable. Check that the types are the same by making a
// nullable copy of both types and then comparing them.
RexCall call = (RexCall) projExpr;
if (call.getOperator() != SqlStdOperatorTable.CAST) {
continue;
}
RexNode castOperand = call.getOperands().get(0);
if (!(castOperand instanceof RexInputRef)) {
continue;
}
RelDataTypeFactory typeFactory = rel.getCluster().getTypeFactory();
RelDataType castType = typeFactory.createTypeWithNullability(projExpr.getType(), true);
RelDataType origType = typeFactory.createTypeWithNullability(castOperand.getType(), true);
if (castType.equals(origType)) {
childColumns.set(((RexInputRef) castOperand).getIndex());
}
} else {
// If the expression will not influence uniqueness of the
// projection, then skip it.
continue;
}
}
// If no columns can affect uniqueness, then return unknown
if (childColumns.cardinality() == 0) {
return null;
}
return RelMetadataQuery.areColumnsUnique(rel.getChild(), childColumns, ignoreNulls);
}
/**
* Creates a key for {@link RexNode} which is the same as another key of another RexNode only if
* the two have both the same type and textual representation. For example, "10" integer and "10"
* bigint result in different keys.
*/
public static String makeKey(RexNode expr) {
String type = expr.getType().getFullTypeString();
String separator = ";";
String node = expr.toString();
StringBuilder keyBuilder =
new StringBuilder(type.length() + separator.length() + node.length());
keyBuilder.append(type).append(separator).append(node);
return keyBuilder.toString();
}
/**
* Determines if a projection is simple.
*
* @param calcRel CalcRel containing the projection
* @param projOrdinals if the projection is simple, returns the ordinals of the projection inputs
* @return rowtype corresponding to the projection, provided it is simple; otherwise null is
* returned
*/
private RelDataType isProjectSimple(CalcRel calcRel, List<Integer> projOrdinals) {
// Loop through projection expressions. If we find a non-simple
// projection expression, simply return.
RexProgram program = calcRel.getProgram();
List<RexLocalRef> projList = program.getProjectList();
int nProjExprs = projList.size();
RelDataType[] types = new RelDataType[nProjExprs];
String[] fieldNames = new String[nProjExprs];
RelDataTypeField[] projFields = calcRel.getRowType().getFields();
for (int i = 0; i < nProjExprs; i++) {
RexNode projExpr = program.expandLocalRef(projList.get(i));
if (projExpr instanceof RexInputRef) {
projOrdinals.add(((RexInputRef) projExpr).getIndex());
types[i] = projExpr.getType();
fieldNames[i] = projFields[i].getName();
continue;
} else if (!(projExpr instanceof RexCall)) {
return null;
}
RexCall rexCall = (RexCall) projExpr;
if (rexCall.getOperator() != SqlStdOperatorTable.castFunc) {
return null;
}
RexNode castOperand = rexCall.getOperands()[0];
if (!(castOperand instanceof RexInputRef)) {
return null;
}
RelDataType castType = projExpr.getType();
RelDataType origType = castOperand.getType();
if (isCastSimple(origType, castType)) {
projOrdinals.add(((RexInputRef) castOperand).getIndex());
types[i] = castType;
fieldNames[i] = projFields[i].getName();
} else {
return null;
}
}
// return the rowtype corresponding to the output of the projection
return calcRel.getCluster().getTypeFactory().createStructType(types, fieldNames);
}
// override RexShuttle
public RexNode visitCall(final RexCall call) {
int i = reducibleExps.indexOf(call);
if (i == -1) {
return super.visitCall(call);
}
RexNode replacement = reducedValues.get(i);
if (addCasts.get(i) && (replacement.getType() != call.getType())) {
// Handle change from nullable to NOT NULL by claiming
// that the result is still nullable, even though
// we know it isn't.
//
// Also, we cannot reduce CAST('abc' AS VARCHAR(4)) to 'abc'.
// If we make 'abc' of type VARCHAR(4), we may later encounter
// the same expression in a ProjectRel's digest where it has
// type VARCHAR(3), and that's wrong.
replacement = rexBuilder.makeCast(call.getType(), replacement);
}
return replacement;
}
protected void executeImpl() throws Exception {
SqlCall call = (SqlCall) subq;
SqlSelect select = (SqlSelect) call.getOperands()[0];
// Convert the SqlNode tree to a RelNode tree; we need to do this
// here so the RelNode tree is associated with the new preparing
// stmt.
FarragoPreparingStmt preparingStmt = (FarragoPreparingStmt) getPreparingStmt();
SqlValidator validator = preparingStmt.getSqlValidator();
SqlToRelConverter sqlConverter = preparingStmt.getSqlToRelConverter(validator, preparingStmt);
preparingStmt.setParentStmt(FennelRelUtil.getPreparingStmt(parentConverter.getCluster()));
// Add to the new converter any subqueries that have already been
// converted by the parent so we can avoid re-executing them
sqlConverter.addConvertedNonCorrSubqs(parentConverter.getMapConvertedNonCorrSubqs());
RelNode plan = sqlConverter.convertQuery(select, true, true);
// The subquery cannot have dynamic parameters
if (sqlConverter.getDynamicParamCount() > 0) {
failed = true;
return;
}
List<RexNode> exprs = new ArrayList<RexNode>();
RelDataType resultType = null;
if (!isExists) {
// Non-EXISTS subqueries need to be converted to single-value
// subqueries
plan = sqlConverter.convertToSingleValueSubq(select, plan);
// Create a dummy expression to store the type of the result.
// When setting the type, derive the type based on what a
// scalar subquery should return and create the type from the
// type factory of the parent query.
resultType = call.getOperator().deriveType(validator, validator.getFromScope(select), call);
resultType = rexBuilder.getTypeFactory().copyType(resultType);
exprs.add(rexBuilder.makeInputRef(resultType, 0));
}
plan = sqlConverter.decorrelate(select, plan);
// If the subquery is part of an EXPLAIN PLAN statement, don't
// execute the subquery, but instead just return a dynamic parameter
// as a placeholder for the subquery result. Otherwise, execute
// the query to produce the constant expression. Cast the expression
// as needed so the type matches the expected result type.
RexNode constExpr;
if (isExplain) {
if (isExists) {
resultType = rexBuilder.getTypeFactory().createSqlType(SqlTypeName.BOOLEAN);
}
constExpr =
rexBuilder.makeDynamicParam(
resultType, parentConverter.getDynamicParamCountInExplain(true));
results.add(constExpr);
} else {
executePlan(plan, exprs, isExists, false);
if (!failed && !isExists) {
constExpr = results.get(0);
if (constExpr.getType() != resultType) {
constExpr = rexBuilder.makeCast(resultType, constExpr);
results.set(0, constExpr);
}
}
}
}