public SortRel copy(
RelTraitSet traitSet,
RelNode newInput,
RelCollation newCollation,
RexNode offset,
RexNode fetch) {
assert traitSet.containsIfApplicable(Convention.NONE);
return new SortRel(getCluster(), traitSet, newInput, newCollation, offset, fetch);
}
/**
* Creates a sorter.
*
* @param cluster Cluster this relational expression belongs to
* @param traits Traits
* @param child input relational expression
* @param collation array of sort specifications
* @param offset Expression for number of rows to discard before returning first row
* @param fetch Expression for number of rows to fetch
*/
public SortRel(
RelOptCluster cluster,
RelTraitSet traits,
RelNode child,
RelCollation collation,
RexNode offset,
RexNode fetch) {
super(cluster, traits, child);
this.collation = collation;
this.offset = offset;
this.fetch = fetch;
assert traits.containsIfApplicable(collation) : "traits=" + traits + ", collation=" + collation;
assert !(fetch == null && offset == null && collation.getFieldCollations().isEmpty())
: "trivial sort";
ImmutableList.Builder<RexNode> builder = ImmutableList.builder();
for (RelFieldCollation field : collation.getFieldCollations()) {
int index = field.getFieldIndex();
builder.add(cluster.getRexBuilder().makeInputRef(child, index));
}
fieldExps = builder.build();
}