/
qdifference.cpp
49 lines (42 loc) · 1.29 KB
/
qdifference.cpp
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// Copyright (c) 2000 Suneido Software Corp. All rights reserved
// Licensed under GPLv2
#include "qdifference.h"
Query* Query::make_difference(Query* s1, Query* s2) {
return new Difference(s1, s2);
}
Difference::Difference(Query* s1, Query* s2) : Compatible(s1, s2) {
}
void Difference::out(Ostream& os) const {
os << "(" << *source << ") MINUS";
if (disjoint != "")
os << "-DISJOINT";
if (!nil(ki))
os << "^" << ki;
os << " (" << *source2 << ") ";
}
Query* Difference::transform() {
// remove disjoint difference
if (disjoint != "")
return source->transform();
else
return Compatible::transform();
}
double Difference::optimize2(const Fields& index, const Fields& needs,
const Fields& firstneeds, bool is_cursor, bool freeze) {
if (disjoint != "")
return 0;
Fields cols1 = source->columns();
Fields cols2 = source2->columns();
Fields needs1 = intersect(needs, cols1);
Fields needs2 = intersect(needs, cols2);
ki = source2->key_index(needs2);
Fields needs1_k = intersect(cols1, ki);
return source->optimize(index, needs1, needs1_k, is_cursor, freeze) +
source2->optimize(ki, needs2, Fields(), is_cursor, freeze);
}
Row Difference::get(Dir dir) {
Row row;
while (Eof != (row = source->get(dir)) && isdup(row))
;
return row;
}