Ejemplo n.º 1
0
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
}
Ejemplo n.º 2
0
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)
	}
}