[DNM] sql: combine DDecimal alloc with big.Int coefficient alloc

Similar to the previous commit, but for non-vectorized execution.

Needs polish.

pkg/ccl/importccl/read_import_mysql.go

@@ -264,7 +264,7 @@ func mysqlValueToDatum(
 				return tree.NewDFloat(-*i), nil
 			case *tree.DDecimal:
 				dec := &i.Decimal
-				dd := &tree.DDecimal{}
+				dd := tree.NewDDecimal()
 				dd.Decimal.Neg(dec)
 				return dd, nil
 			default:

pkg/ccl/importccl/read_import_workload.go

@@ -17,7 +17,6 @@ import (
 	"sync/atomic"
 	"unsafe"
 
-	"github.com/cockroachdb/apd/v2"
 	"github.com/cockroachdb/cockroach/pkg/cloud"
 	"github.com/cockroachdb/cockroach/pkg/col/coldata"
 	"github.com/cockroachdb/cockroach/pkg/roachpb"
@@ -73,8 +72,9 @@ func makeDatumFromColOffset(
 			case types.IntFamily:
 				return alloc.NewDInt(tree.DInt(col.Int64()[rowIdx])), nil
 			case types.DecimalFamily:
-				d := *apd.New(col.Int64()[rowIdx], 0)
-				return alloc.NewDDecimal(tree.DDecimal{Decimal: d}), nil
+				d := alloc.NewDDecimal(tree.DDecimal{})
+				d.SetInt64(col.Int64()[rowIdx])
+				return d, nil
 			case types.DateFamily:
 				date, err := pgdate.MakeDateFromUnixEpoch(col.Int64()[rowIdx])
 				if err != nil {
@@ -93,11 +93,11 @@ func makeDatumFromColOffset(
 		case types.FloatFamily:
 			return alloc.NewDFloat(tree.DFloat(col.Float64()[rowIdx])), nil
 		case types.DecimalFamily:
-			var d apd.Decimal
+			d := alloc.NewDDecimal(tree.DDecimal{})
 			if _, err := d.SetFloat64(col.Float64()[rowIdx]); err != nil {
 				return nil, err
 			}
-			return alloc.NewDDecimal(tree.DDecimal{Decimal: d}), nil
+			return d, nil
 		}
 	case types.BytesFamily:
 		switch hint.Family() {

pkg/sql/colexec/colexectestutils/utils.go

@@ -1401,8 +1401,15 @@ func tupleEquals(expected Tuple, actual Tuple, evalCtx *tree.EvalContext) bool {
 			}
 			// Special case for decimals.
 			if d1, ok := actual[i].(apd.Decimal); ok {
-				if f2, ok := expected[i].(float64); ok {
-					d2, _, err := apd.NewFromString(fmt.Sprintf("%f", f2))
+				switch t := expected[i].(type) {
+				case apd.Decimal:
+					if d1.Cmp(&t) == 0 {
+						continue
+					} else {
+						return false
+					}
+				case float64:
+					d2, _, err := apd.NewFromString(fmt.Sprintf("%f", t))
 					if err == nil && d1.Cmp(d2) == 0 {
 						continue
 					} else {

pkg/sql/colexec/execgen/cmd/execgen/vec_to_datum_gen.go

@@ -67,14 +67,10 @@ var vecToDatumConversionTmpls = map[types.Family]string{
 	types.BoolFamily: `%[1]s := tree.MakeDBool(tree.DBool(%[2]s))`,
 	// Note that currently, regardless of the integer's width, we always return
 	// INT8, so there is a single conversion template for IntFamily.
-	types.IntFamily:   `%[1]s := %[3]s.NewDInt(tree.DInt(%[2]s))`,
-	types.FloatFamily: `%[1]s := %[3]s.NewDFloat(tree.DFloat(%[2]s))`,
-	types.DecimalFamily: `  %[1]s := %[3]s.NewDDecimal(tree.DDecimal{Decimal: %[2]s})
-							// Clear the Coeff so that the Set below allocates a new slice for the
-							// Coeff.abs field.
-							%[1]s.Coeff = big.Int{}
-							%[1]s.Coeff.Set(&%[2]s.Coeff)`,
-	types.DateFamily: `%[1]s := %[3]s.NewDDate(tree.DDate{Date: pgdate.MakeCompatibleDateFromDisk(%[2]s)})`,
+	types.IntFamily:     `%[1]s := %[3]s.NewDInt(tree.DInt(%[2]s))`,
+	types.FloatFamily:   `%[1]s := %[3]s.NewDFloat(tree.DFloat(%[2]s))`,
+	types.DecimalFamily: `%[1]s := %[3]s.NewDDecimal(tree.DDecimal{Decimal: %[2]s})`,
+	types.DateFamily:    `%[1]s := %[3]s.NewDDate(tree.DDate{Date: pgdate.MakeCompatibleDateFromDisk(%[2]s)})`,
 	types.BytesFamily: `// Note that there is no need for a copy since DBytes uses a string
 						// as underlying storage, which will perform the copy for us.
 						%[1]s := %[3]s.NewDBytes(tree.DBytes(%[2]s))`,

pkg/sql/exec_util.go

@@ -1554,7 +1554,7 @@ func golangFillQueryArguments(args ...interface{}) (tree.Datums, error) {
 		case bitarray.BitArray:
 			d = &tree.DBitArray{BitArray: t}
 		case *apd.Decimal:
-			dd := &tree.DDecimal{}
+			dd := tree.NewDDecimal()
 			dd.Set(t)
 			d = dd
 		case security.SQLUsername:

pkg/sql/randgen/datum.go

@@ -116,7 +116,7 @@ func RandDatumWithNullChance(rng *rand.Rand, typ *types.T, nullChance int) tree.
 		}
 		return tree.NewDGeometry(geogen.RandomGeometry(rng, gm.SRID))
 	case types.DecimalFamily:
-		d := &tree.DDecimal{}
+		d := tree.NewDDecimal()
 		// int64(rng.Uint64()) to get negative numbers, too
 		d.Decimal.SetFinite(int64(rng.Uint64()), int32(rng.Intn(40)-20))
 		return d

pkg/sql/rowenc/datum_alloc.go

@@ -34,7 +34,7 @@ type DatumAlloc struct {
 	dstringAlloc      []tree.DString
 	dbytesAlloc       []tree.DBytes
 	dbitArrayAlloc    []tree.DBitArray
-	ddecimalAlloc     []tree.DDecimal
+	ddecimalAlloc     []tree.DDecimalAlloc
 	ddateAlloc        []tree.DDate
 	denumAlloc        []tree.DEnum
 	dbox2dAlloc       []tree.DBox2D
@@ -170,10 +170,10 @@ func (a *DatumAlloc) NewDDecimal(v tree.DDecimal) *tree.DDecimal {
 	}
 	buf := &a.ddecimalAlloc
 	if len(*buf) == 0 {
-		*buf = make([]tree.DDecimal, a.AllocSize)
+		*buf = make([]tree.DDecimalAlloc, a.AllocSize)
 	}
-	r := &(*buf)[0]
-	*r = v
+	r := (*buf)[0].Get()
+	r.Set(&v.Decimal)
 	*buf = (*buf)[1:]
 	return r
 }

pkg/sql/rowexec/processor_utils_test.go

@@ -60,7 +60,7 @@ func toEncDatum(datumType *types.T, v interface{}) rowenc.EncDatum {
 		switch concreteType := v.(type) {
 		case int:
 			if datumType.Family() == types.DecimalFamily {
-				dd := &tree.DDecimal{}
+				dd := tree.NewDDecimal()
 				dd.SetInt64(int64(v.(int)))
 				return dd
 			}

pkg/sql/sem/builtins/aggregate_builtins.go

@@ -2577,7 +2577,7 @@ func (a *intSumAggregate) Result() (tree.Datum, error) {
 	if !a.seenNonNull {
 		return tree.DNull, nil
 	}
-	dd := &tree.DDecimal{}
+	dd := tree.NewDDecimal()
 	if a.large {
 		dd.Set(&a.decSum)
 	} else {
@@ -2644,7 +2644,7 @@ func (a *decimalSumAggregate) Result() (tree.Datum, error) {
 	if !a.sawNonNull {
 		return tree.DNull, nil
 	}
-	dd := &tree.DDecimal{}
+	dd := tree.NewDDecimal()
 	dd.Set(&a.sum)
 	return dd, nil
 }
@@ -2947,7 +2947,7 @@ func (a *decimalSqrDiffAggregate) Result() (tree.Datum, error) {
 	if a.count.Cmp(decimalOne) < 0 {
 		return tree.DNull, nil
 	}
-	dd := &tree.DDecimal{}
+	dd := tree.NewDDecimal()
 	dd.Set(&a.sqrDiff)
 	// Remove trailing zeros. Depending on the order in which the input
 	// is processed, some number of trailing zeros could be added to the
@@ -3267,7 +3267,7 @@ func (a *decimalVarianceAggregate) Result() (tree.Datum, error) {
 	if _, err = tree.IntermediateCtx.Sub(a.agg.Tmp(), a.agg.Count(), decimalOne); err != nil {
 		return nil, err
 	}
-	dd := &tree.DDecimal{}
+	dd := tree.NewDDecimal()
 	if _, err = tree.DecimalCtx.Quo(&dd.Decimal, &sqrDiff.(*tree.DDecimal).Decimal, a.agg.Tmp()); err != nil {
 		return nil, err
 	}
@@ -3382,7 +3382,7 @@ func (a *decimalVarPopAggregate) Result() (tree.Datum, error) {
 	if err != nil {
 		return nil, err
 	}
-	dd := &tree.DDecimal{}
+	dd := tree.NewDDecimal()
 	if _, err = tree.DecimalCtx.Quo(&dd.Decimal, &sqrDiff.(*tree.DDecimal).Decimal, a.agg.Count()); err != nil {
 		return nil, err
 	}

pkg/sql/sem/builtins/aggregate_builtins_test.go

@@ -499,7 +499,7 @@ func makeDecimalTestDatum(count int) []tree.Datum {
 
 	vals := make([]tree.Datum, count)
 	for i := range vals {
-		dd := &tree.DDecimal{}
+		dd := tree.NewDDecimal()
 		if _, err := dd.SetFloat64(rng.Float64()); err != nil {
 			panic(err)
 		}

pkg/sql/sem/builtins/math_builtins.go

@@ -53,7 +53,7 @@ var mathBuiltins = map[string]builtinDefinition{
 			return tree.NewDFloat(tree.DFloat(math.Abs(x))), nil
 		}, "Calculates the absolute value of `val`.", tree.VolatilityImmutable),
 		decimalOverload1(func(x *apd.Decimal) (tree.Datum, error) {
-			dd := &tree.DDecimal{}
+			dd := tree.NewDDecimal()
 			dd.Abs(x)
 			return dd, nil
 		}, "Calculates the absolute value of `val`.", tree.VolatilityImmutable),
@@ -197,7 +197,7 @@ var mathBuiltins = map[string]builtinDefinition{
 			if y.Sign() == 0 {
 				return nil, tree.ErrDivByZero
 			}
-			dd := &tree.DDecimal{}
+			dd := tree.NewDDecimal()
 			_, err := tree.HighPrecisionCtx.QuoInteger(&dd.Decimal, x, y)
 			return dd, err
 		}, "Calculates the integer quotient of `x`/`y`.", tree.VolatilityImmutable),
@@ -222,7 +222,7 @@ var mathBuiltins = map[string]builtinDefinition{
 			return tree.NewDFloat(tree.DFloat(math.Exp(x))), nil
 		}, "Calculates *e* ^ `val`.", tree.VolatilityImmutable),
 		decimalOverload1(func(x *apd.Decimal) (tree.Datum, error) {
-			dd := &tree.DDecimal{}
+			dd := tree.NewDDecimal()
 			_, err := tree.DecimalCtx.Exp(&dd.Decimal, x)
 			return dd, err
 		}, "Calculates *e* ^ `val`.", tree.VolatilityImmutable),
@@ -233,7 +233,7 @@ var mathBuiltins = map[string]builtinDefinition{
 			return tree.NewDFloat(tree.DFloat(math.Floor(x))), nil
 		}, "Calculates the largest integer not greater than `val`.", tree.VolatilityImmutable),
 		decimalOverload1(func(x *apd.Decimal) (tree.Datum, error) {
-			dd := &tree.DDecimal{}
+			dd := tree.NewDDecimal()
 			_, err := tree.ExactCtx.Floor(&dd.Decimal, x)
 			return dd, err
 		}, "Calculates the largest integer not greater than `val`.", tree.VolatilityImmutable),
@@ -322,7 +322,7 @@ var mathBuiltins = map[string]builtinDefinition{
 				return nil, err
 			}
 
-			dd := &tree.DDecimal{}
+			dd := tree.NewDDecimal()
 			_, err := tree.DecimalCtx.Quo(&dd.Decimal, top, bot)
 			return dd, err
 		}, "Calculates the base `b` log of `val`.", tree.VolatilityImmutable),
@@ -336,7 +336,7 @@ var mathBuiltins = map[string]builtinDefinition{
 			if y.Sign() == 0 {
 				return nil, tree.ErrDivByZero
 			}
-			dd := &tree.DDecimal{}
+			dd := tree.NewDDecimal()
 			_, err := tree.HighPrecisionCtx.Rem(&dd.Decimal, x, y)
 			return dd, err
 		}, "Calculates `x`%`y`.", tree.VolatilityImmutable),
@@ -462,7 +462,7 @@ var mathBuiltins = map[string]builtinDefinition{
 		}, "Determines the sign of `val`: **1** for positive; **0** for 0 values; **-1** for "+
 			"negative.", tree.VolatilityImmutable),
 		decimalOverload1(func(x *apd.Decimal) (tree.Datum, error) {
-			d := &tree.DDecimal{}
+			d := tree.NewDDecimal()
 			d.Decimal.SetInt64(int64(x.Sign()))
 			return d, nil
 		}, "Determines the sign of `val`: **1** for positive; **0** for 0 values; **-1** for "+
@@ -518,7 +518,7 @@ var mathBuiltins = map[string]builtinDefinition{
 			return tree.NewDFloat(tree.DFloat(math.Trunc(x))), nil
 		}, "Truncates the decimal values of `val`.", tree.VolatilityImmutable),
 		decimalOverload1(func(x *apd.Decimal) (tree.Datum, error) {
-			dd := &tree.DDecimal{}
+			dd := tree.NewDDecimal()
 			x.Modf(&dd.Decimal, nil)
 			return dd, nil
 		}, "Truncates the decimal values of `val`.", tree.VolatilityImmutable),
@@ -593,7 +593,7 @@ var ceilImpl = makeBuiltin(defProps(),
 		return tree.NewDFloat(tree.DFloat(math.Ceil(x))), nil
 	}, "Calculates the smallest integer not smaller than `val`.", tree.VolatilityImmutable),
 	decimalOverload1(func(x *apd.Decimal) (tree.Datum, error) {
-		dd := &tree.DDecimal{}
+		dd := tree.NewDDecimal()
 		_, err := tree.ExactCtx.Ceil(&dd.Decimal, x)
 		if dd.IsZero() {
 			dd.Negative = false
@@ -616,7 +616,7 @@ var powImpls = makeBuiltin(defProps(),
 		return tree.NewDFloat(tree.DFloat(math.Pow(x, y))), nil
 	}, "Calculates `x`^`y`.", tree.VolatilityImmutable),
 	decimalOverload2("x", "y", func(x, y *apd.Decimal) (tree.Datum, error) {
-		dd := &tree.DDecimal{}
+		dd := tree.NewDDecimal()
 		_, err := tree.DecimalCtx.Pow(&dd.Decimal, x, y)
 		return dd, err
 	}, "Calculates `x`^`y`.", tree.VolatilityImmutable),
@@ -646,7 +646,7 @@ func decimalLogFn(
 		case 0:
 			return nil, errLogOfZero
 		}
-		dd := &tree.DDecimal{}
+		dd := tree.NewDDecimal()
 		_, err := logFn(&dd.Decimal, x)
 		return dd, err
 	}, info, tree.VolatilityImmutable)
@@ -730,7 +730,7 @@ func roundDDecimal(d *tree.DDecimal, scale int32) (tree.Datum, error) {
 }
 
 func roundDecimal(x *apd.Decimal, scale int32) (tree.Datum, error) {
-	dd := &tree.DDecimal{}
+	dd := tree.NewDDecimal()
 	_, err := tree.HighPrecisionCtx.Quantize(&dd.Decimal, x, -scale)
 	return dd, err
 }

pkg/sql/sem/builtins/window_frame_builtins.go

@@ -246,9 +246,9 @@ func (w *slidingWindowSumFunc) removeAllBefore(
 		case *tree.DInt:
 			err = w.agg.Add(ctx, tree.NewDInt(-*v))
 		case *tree.DDecimal:
-			d := tree.DDecimal{}
+			d := tree.NewDDecimal()
 			d.Neg(&v.Decimal)
-			err = w.agg.Add(ctx, &d)
+			err = w.agg.Add(ctx, d)
 		case *tree.DFloat:
 			err = w.agg.Add(ctx, tree.NewDFloat(-*v))
 		case *tree.DInterval:
@@ -405,7 +405,7 @@ func (w *avgWindowFunc) Compute(
 		_, err := tree.DecimalCtx.Quo(&avg.Decimal, &t.Decimal, count)
 		return &avg, err
 	case *tree.DInt:
-		dd := tree.DDecimal{}
+		dd := tree.NewDDecimal()
 		dd.SetInt64(int64(*t))
 		var avg tree.DDecimal
 		count := apd.New(int64(frameSize), 0)

pkg/sql/sem/tree/datum.go

@@ -996,6 +996,35 @@ type DDecimal struct {
 	apd.Decimal
 }
 
+// DDecimalAlloc attempts to minimize heap allocations when using a DDecimal.
+// Each Decimal maintains (through an embedded big.Int) an internal reference
+// to a variable-length coefficient, which is represented by a []big.Word. To
+// minimize the number of individual heap allocations, we allocate a small
+// []big.Word alongside the DDecimal and wire the two up. big.Int will avoid
+// re-allocating unless its coefficient exceeds the initial capacity. We set
+// this capacity to accommodate any coefficient that would fit in a 64-bit
+// integer.
+type DDecimalAlloc struct {
+	d DDecimal
+	w [unsafe.Sizeof(uint64(0)) / unsafe.Sizeof(big.Word(0))]big.Word
+}
+
+// Get returns the allocated DDecimal.
+func (d *DDecimalAlloc) Get() *DDecimal {
+	if d.d.Coeff.Bits() == nil {
+		d.d.Coeff.SetBits(d.w[:])
+	}
+	return &d.d
+}
+
+// NewDDecimal is a helper routine to create a *DDecimal. The function attempts
+// to allocate the Decimal and its internal, variable-length references in a
+// single heap allocation.
+func NewDDecimal() *DDecimal {
+	a := new(DDecimalAlloc)
+	return a.Get()
+}
+
 // MustBeDDecimal attempts to retrieve a DDecimal from an Expr, panicking if the
 // assertion fails.
 func MustBeDDecimal(e Expr) DDecimal {
@@ -1009,7 +1038,7 @@ func MustBeDDecimal(e Expr) DDecimal {
 // ParseDDecimal parses and returns the *DDecimal Datum value represented by the
 // provided string, or an error if parsing is unsuccessful.
 func ParseDDecimal(s string) (*DDecimal, error) {
-	dd := &DDecimal{}
+	dd := NewDDecimal()
 	err := dd.SetString(s)
 	return dd, err
 }