func (n *valuesNode) Less(i, j int) bool {
// TODO(pmattis): An alternative to this type of field-based comparison would
// be to construct a sort-key per row using encodeTableKey(). Using a
// sort-key approach would likely fit better with a disk-based sort.
ra, rb := n.rows[i], n.rows[j]
for _, c := range n.ordering {
var da, db parser.Datum
if c.direction == encoding.Ascending {
da = ra[c.colIdx]
db = rb[c.colIdx]
} else {
da = rb[c.colIdx]
db = ra[c.colIdx]
}
// TODO(pmattis): This is assuming that the datum types are compatible. I'm
// not sure this always holds as `CASE` expressions can return different
// types for a column for different rows. Investigate how other RDBMs
// handle this.
if c := da.Compare(db); c < 0 {
return true
} else if c > 0 {
return false
}
}
return true
}
func TestEncDatumCompare(t *testing.T) {
a := &DatumAlloc{}
rng, _ := randutil.NewPseudoRand()
for typ := ColumnType_Kind(0); int(typ) < len(ColumnType_Kind_value); typ++ {
// Generate two datums d1 < d2
var d1, d2 parser.Datum
for {
d1 = RandDatum(rng, typ, false)
d2 = RandDatum(rng, typ, false)
if cmp := d1.Compare(d2); cmp < 0 {
break
}
}
v1 := &EncDatum{}
v1.SetDatum(typ, d1)
v2 := &EncDatum{}
v2.SetDatum(typ, d2)
if val, err := v1.Compare(a, v2); err != nil {
t.Fatal(err)
} else if val != -1 {
t.Errorf("compare(1, 2) = %d", val)
}
asc := DatumEncoding_ASCENDING_KEY
desc := DatumEncoding_DESCENDING_KEY
noncmp := DatumEncoding_VALUE
checkEncDatumCmp(t, a, v1, v2, asc, asc, -1, false)
checkEncDatumCmp(t, a, v2, v1, asc, asc, +1, false)
checkEncDatumCmp(t, a, v1, v1, asc, asc, 0, false)
checkEncDatumCmp(t, a, v2, v2, asc, asc, 0, false)
checkEncDatumCmp(t, a, v1, v2, desc, desc, -1, false)
checkEncDatumCmp(t, a, v2, v1, desc, desc, +1, false)
checkEncDatumCmp(t, a, v1, v1, desc, desc, 0, false)
checkEncDatumCmp(t, a, v2, v2, desc, desc, 0, false)
checkEncDatumCmp(t, a, v1, v2, noncmp, noncmp, -1, true)
checkEncDatumCmp(t, a, v2, v1, desc, noncmp, +1, true)
checkEncDatumCmp(t, a, v1, v1, asc, desc, 0, true)
checkEncDatumCmp(t, a, v2, v2, desc, asc, 0, true)
}
}