public Double getDistinctRowCount(SemiJoin rel, ImmutableBitSet groupKey, RexNode predicate) {
if (predicate == null || predicate.isAlwaysTrue()) {
if (groupKey.isEmpty()) {
return 1D;
}
}
// create a RexNode representing the selectivity of the
// semijoin filter and pass it to getDistinctRowCount
RexNode newPred = RelMdUtil.makeSemiJoinSelectivityRexNode(rel);
if (predicate != null) {
RexBuilder rexBuilder = rel.getCluster().getRexBuilder();
newPred = rexBuilder.makeCall(SqlStdOperatorTable.AND, newPred, predicate);
}
return RelMetadataQuery.getDistinctRowCount(rel.getLeft(), groupKey, newPred);
}
