public Double getPercentageOriginalRows(UnionRelBase rel) {
double numerator = 0.0;
double denominator = 0.0;
// Ignore rel.isDistinct() because it's the same as an aggregate.
// REVIEW jvs 28-Mar-2006: The original Broadbase formula was broken.
// It was multiplying percentage into the numerator term rather than
// than dividing it out of the denominator term, which would be OK if
// there weren't summation going on. Probably the cause of the error
// was the desire to avoid division by zero, which I don't know how to
// handle so I punt, meaning we return a totally wrong answer in the
// case where a huge table has been completely filtered away.
for (RelNode input : rel.getInputs()) {
double rowCount = RelMetadataQuery.getRowCount(input);
double percentage = RelMetadataQuery.getPercentageOriginalRows(input);
if (percentage != 0.0) {
denominator += rowCount / percentage;
numerator += rowCount;
}
}
return quotientForPercentage(numerator, denominator);
}
// Ditto for getNonCumulativeCost
public RelOptCost getCumulativeCost(RelNode rel) {
RelOptCost cost = RelMetadataQuery.getNonCumulativeCost(rel);
List<RelNode> inputs = rel.getInputs();
for (RelNode input : inputs) {
cost = cost.plus(RelMetadataQuery.getCumulativeCost(input));
}
return cost;
}
public Double getPercentageOriginalRows(JoinRelBase rel) {
// Assume any single-table filter conditions have already
// been pushed down.
// REVIEW jvs 28-Mar-2006: As with aggregation, this is
// oversimplified.
// REVIEW jvs 28-Mar-2006: need any special casing for SemiJoinRel?
double left = RelMetadataQuery.getPercentageOriginalRows(rel.getLeft());
double right = RelMetadataQuery.getPercentageOriginalRows(rel.getRight());
return left * right;
}
public Double getPercentageOriginalRows(AggregateRelBase rel) {
// REVIEW jvs 28-Mar-2006: The assumption here seems to be that
// aggregation does not apply any filtering, so it does not modify the
// percentage. That's very much oversimplified.
return RelMetadataQuery.getPercentageOriginalRows(rel.getChild());
}
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);
}
// Catch-all rule when none of the others apply.
public Double getPercentageOriginalRows(RelNode rel) {
if (rel.getInputs().size() > 1) {
// No generic formula available for multiple inputs.
return null;
}
if (rel.getInputs().size() == 0) {
// Assume no filtering happening at leaf.
return 1.0;
}
RelNode child = rel.getInputs().get(0);
Double childPercentage = RelMetadataQuery.getPercentageOriginalRows(child);
if (childPercentage == null) {
return null;
}
// Compute product of percentage filtering from this rel (assuming any
// filtering is the effect of single-table filters) with the percentage
// filtering performed by the child.
Double relPercentage =
quotientForPercentage(
RelMetadataQuery.getRowCount(rel), RelMetadataQuery.getRowCount(child));
if (relPercentage == null) {
return null;
}
double percent = relPercentage * childPercentage;
// this check is needed in cases where this method is called on a
// physical rel
if ((percent < 0.0) || (percent > 1.0)) {
return null;
}
return relPercentage * childPercentage;
}
public RelOptCost computeSelfCost(RelOptPlanner planner) {
double dRows = RelMetadataQuery.getRowCount(this);
double dCpu = RelMetadataQuery.getRowCount(getChild()) * program.getExprCount();
double dIo = 0;
return planner.makeCost(dRows, dCpu, dIo);
}
public Boolean areColumnsUnique(CorrelatorRel rel, BitSet columns, boolean ignoreNulls) {
return RelMetadataQuery.areColumnsUnique(rel.getLeft(), columns, ignoreNulls);
}
public Boolean areColumnsUnique(SortRel rel, BitSet columns, boolean ignoreNulls) {
return RelMetadataQuery.areColumnsUnique(rel.getChild(), columns, ignoreNulls);
}
public Boolean areColumnsUnique(SemiJoinRel rel, BitSet columns, boolean ignoreNulls) {
// only return the unique keys from the LHS since a semijoin only
// returns the LHS
return RelMetadataQuery.areColumnsUnique(rel.getLeft(), columns, ignoreNulls);
}
public Boolean areColumnsUnique(JoinRelBase rel, BitSet columns, boolean ignoreNulls) {
if (columns.cardinality() == 0) {
return false;
}
final RelNode left = rel.getLeft();
final RelNode right = rel.getRight();
// Divide up the input column mask into column masks for the left and
// right sides of the join
BitSet leftColumns = new BitSet();
BitSet rightColumns = new BitSet();
int nLeftColumns = left.getRowType().getFieldCount();
for (int bit : BitSets.toIter(columns)) {
if (bit < nLeftColumns) {
leftColumns.set(bit);
} else {
rightColumns.set(bit - nLeftColumns);
}
}
// If the original column mask contains columns from both the left and
// right hand side, then the columns are unique if and only if they're
// unique for their respective join inputs
Boolean leftUnique = RelMetadataQuery.areColumnsUnique(left, leftColumns, ignoreNulls);
Boolean rightUnique = RelMetadataQuery.areColumnsUnique(right, rightColumns, ignoreNulls);
if ((leftColumns.cardinality() > 0) && (rightColumns.cardinality() > 0)) {
if ((leftUnique == null) || (rightUnique == null)) {
return null;
} else {
return leftUnique && rightUnique;
}
}
// If we're only trying to determine uniqueness for columns that
// originate from one join input, then determine if the equijoin
// columns from the other join input are unique. If they are, then
// the columns are unique for the entire join if they're unique for
// the corresponding join input, provided that input is not null
// generating.
final JoinInfo joinInfo = rel.analyzeCondition();
if (leftColumns.cardinality() > 0) {
if (rel.getJoinType().generatesNullsOnLeft()) {
return false;
}
Boolean rightJoinColsUnique =
RelMetadataQuery.areColumnsUnique(right, joinInfo.rightSet(), ignoreNulls);
if ((rightJoinColsUnique == null) || (leftUnique == null)) {
return null;
}
return rightJoinColsUnique && leftUnique;
} else if (rightColumns.cardinality() > 0) {
if (rel.getJoinType().generatesNullsOnRight()) {
return false;
}
Boolean leftJoinColsUnique =
RelMetadataQuery.areColumnsUnique(left, joinInfo.leftSet(), ignoreNulls);
if ((leftJoinColsUnique == null) || (rightUnique == null)) {
return null;
}
return leftJoinColsUnique && rightUnique;
}
throw new AssertionError();
}
