Create an arbitrary-precision decimal encoding scheme

The encoding is based on sqlite4's key encoding:
http://sqlite.org/src4/doc/trunk/www/key_encoding.wiki

GLOCKFILE

@@ -19,6 +19,7 @@ github.com/cockroachdb/c-lz4 c40aaae2fc50293eb8750b34632bc3efe813e23f
 github.com/cockroachdb/c-protobuf 4feb192131ea08dfbd7253a00868ad69cbb61b81
 github.com/cockroachdb/c-rocksdb b7fb7bddcb55be35eacdf67e9e2c931083ce02c4
 github.com/cockroachdb/c-snappy 5c6d0932e0adaffce4bfca7bdf2ac37f79952ccf
+github.com/cockroachdb/decimal 0fab2d0647ef3cdf007d2c3fa1f56efebfb365c9
 github.com/cockroachdb/yacc 443154b1852a8702b07d675da6cd97cd9177a316
 github.com/codahale/hdrhistogram 954f16e8b9ef0e5d5189456aa4c1202758e04f17
 github.com/coreos/etcd 8199147cf859882f625523446c28ae2e53b2432f
@@ -45,7 +46,6 @@ github.com/peterh/liner d5e5aeeb67ca5aeeddeb0b6c3af05421ff63a0b6
 github.com/rcrowley/go-metrics 51425a2415d21afadfd55cd93432c0bc69e9598d
 github.com/robfig/glock cb3c3ec56de988289cab7bbd284eddc04dfee6c9
 github.com/samalba/dockerclient 548a5825c12336eb640190d7eb253e155fc286ad
-github.com/shopspring/decimal af95951b3f91e0748623df28c8756ed65f805161
 github.com/spf13/cobra 9c9300901990faada0c5fb3b5730f452585c7c2b
 github.com/spf13/pflag 7f60f83a2c81bc3c3c0d5297f61ddfa68da9d3b7
 github.com/tebeka/go2xunit fff0d031ea2b81ed06c367293219e4bc005235d0

client/util.go

@@ -22,8 +22,8 @@ import (
 	"time"
 
 	"github.com/cockroachdb/cockroach/roachpb"
+	"github.com/cockroachdb/decimal"
 	"github.com/gogo/protobuf/proto"
-	"github.com/shopspring/decimal"
 )
 
 // TODO(pmattis): The methods in this file needs tests.
@@ -67,8 +67,8 @@ func marshalValue(v interface{}) (roachpb.Value, error) {
 		return r, nil
 
 	case decimal.Decimal:
-		r.SetDecimal(t)
-		return r, nil
+		err := r.SetDecimal(t)
+		return r, err
 
 	case roachpb.Key:
 		r.SetBytes([]byte(t))

keys/printer.go

@@ -21,7 +21,6 @@ import (
 	"fmt"
 	"strconv"
 	"strings"
-	"time"
 
 	"github.com/cockroachdb/cockroach/roachpb"
 	"github.com/cockroachdb/cockroach/util/encoding"
@@ -203,64 +202,7 @@ func print(key roachpb.Key) string {
 }
 
 func decodeKeyPrint(key roachpb.Key) string {
-	var buf bytes.Buffer
-	for k := 0; len(key) > 0; k++ {
-		var err error
-		switch encoding.PeekType(key) {
-		case encoding.Null:
-			key, _ = encoding.DecodeIfNull(key)
-			fmt.Fprintf(&buf, "/NULL")
-		case encoding.NotNull:
-			key, _ = encoding.DecodeIfNotNull(key)
-			fmt.Fprintf(&buf, "/#")
-		case encoding.Int:
-			var i int64
-			key, i, err = encoding.DecodeVarintAscending(key)
-			if err == nil {
-				fmt.Fprintf(&buf, "/%d", i)
-			}
-		case encoding.Float:
-			var f float64
-			key, f, err = encoding.DecodeFloatAscending(key, nil)
-			if err == nil {
-				fmt.Fprintf(&buf, "/%f", f)
-			}
-		case encoding.Bytes:
-			var s string
-			key, s, err = encoding.DecodeStringAscending(key, nil)
-			if err == nil {
-				fmt.Fprintf(&buf, "/%q", s)
-			}
-		case encoding.BytesDesc:
-			var s string
-			key, s, err = encoding.DecodeStringDescending(key, nil)
-			if err == nil {
-				fmt.Fprintf(&buf, "/%q", s)
-			}
-		case encoding.Time:
-			var t time.Time
-			key, t, err = encoding.DecodeTimeAscending(key)
-			if err == nil {
-				fmt.Fprintf(&buf, "/%s", t.UTC().Format(time.UnixDate))
-			}
-		case encoding.TimeDesc:
-			var t time.Time
-			key, t, err = encoding.DecodeTimeDescending(key)
-			if err == nil {
-				fmt.Fprintf(&buf, "/%s", t.UTC().Format(time.UnixDate))
-			}
-		default:
-			// This shouldn't ever happen, but if it does let the loop exit.
-			fmt.Fprintf(&buf, "/%q", []byte(key))
-			key = nil
-		}
-
-		if err != nil {
-			fmt.Fprintf(&buf, "/<%v>", err)
-			continue
-		}
-	}
-	return buf.String()
+	return encoding.PrettyPrintValue(key, "/")
 }
 
 // PrettyPrint prints the key in a human readable format:

keys/printer_test.go

@@ -17,12 +17,14 @@
 package keys
 
 import (
+	"math"
 	"testing"
 	"time"
 
 	"github.com/cockroachdb/cockroach/roachpb"
 	"github.com/cockroachdb/cockroach/util/encoding"
 	"github.com/cockroachdb/cockroach/util/leaktest"
+	"github.com/cockroachdb/decimal"
 )
 
 func TestPrettyPrint(t *testing.T) {
@@ -75,6 +77,12 @@ func TestPrettyPrint(t *testing.T) {
 		{MakeKey(MakeTablePrefix(42),
 			roachpb.RKey(encoding.EncodeFloatDescending(nil, float64(-233.221112)))),
 			"/Table/42/233.221112"},
+		{MakeKey(MakeTablePrefix(42),
+			roachpb.RKey(encoding.EncodeFloatAscending(nil, math.Inf(1)))),
+			"/Table/42/+Inf"},
+		{MakeKey(MakeTablePrefix(42),
+			roachpb.RKey(encoding.EncodeFloatAscending(nil, math.NaN()))),
+			"/Table/42/NaN"},
 		{MakeKey(MakeTablePrefix(42),
 			roachpb.RKey(encoding.EncodeVarintAscending(nil, 1222)),
 			roachpb.RKey(encoding.EncodeStringAscending(nil, "handsome man"))),
@@ -104,6 +112,12 @@ func TestPrettyPrint(t *testing.T) {
 		{MakeKey(MakeTablePrefix(42),
 			roachpb.RKey(encoding.EncodeTimeDescending(nil, tm))),
 			"/Table/42/Sat Mar  7 11:06:39 UTC 2015"},
+		{MakeKey(MakeTablePrefix(42),
+			roachpb.RKey(encoding.EncodeDecimalAscending(nil, decimal.New(1234, -2)))),
+			"/Table/42/12.34"},
+		{MakeKey(MakeTablePrefix(42),
+			roachpb.RKey(encoding.EncodeDecimalDescending(nil, decimal.New(1234, -2)))),
+			"/Table/42/-12.34"},
 
 		// others
 		{MakeKey([]byte("")), "/Min"},

roachpb/data.go

@@ -23,6 +23,7 @@ import (
 	"hash"
 	"hash/crc32"
 	"math"
+	"math/big"
 	"math/rand"
 	"sort"
 	"strconv"
@@ -33,8 +34,8 @@ import (
 	"github.com/cockroachdb/cockroach/util"
 	"github.com/cockroachdb/cockroach/util/encoding"
 	"github.com/cockroachdb/cockroach/util/uuid"
+	"github.com/cockroachdb/decimal"
 	"github.com/gogo/protobuf/proto"
-	"github.com/shopspring/decimal"
 )
 
 const (
@@ -421,17 +422,26 @@ func (v *Value) SetProto(msg proto.Message) error {
 // SetTime encodes the specified time value into the bytes field of the
 // receiver, sets the tag and clears the checksum.
 func (v *Value) SetTime(t time.Time) {
-	v.RawBytes = make([]byte, headerSize, 16)
-	v.RawBytes = encoding.EncodeTimeAscending(v.RawBytes[:headerSize], t)
+	const encodingSizeOverestimate = 11
+	v.RawBytes = make([]byte, headerSize, headerSize+encodingSizeOverestimate)
+	v.RawBytes = encoding.EncodeTimeAscending(v.RawBytes, t)
 	v.setTag(ValueType_TIME)
 }
 
 // SetDecimal encodes the specified decimal value into the bytes field of
 // the receiver, sets the tag and clears the checksum.
-func (v *Value) SetDecimal(d decimal.Decimal) {
-	v.RawBytes = make([]byte, headerSize, 16)
-	v.RawBytes = encoding.EncodeDecimalAscending(v.RawBytes[:headerSize], d)
+func (v *Value) SetDecimal(d decimal.Decimal) error {
+	// TODO(nvanbenschoten) Deal with exponent normalization.
+	bb, err := d.BigInt().GobEncode()
+	if err != nil {
+		return fmt.Errorf("failed to Gob encode decimal's big.Int: %v", err)
+	}
+	v.RawBytes = make([]byte, headerSize+binary.MaxVarintLen64+len(bb))
+	n := binary.PutVarint(v.RawBytes[headerSize:], int64(d.Exponent()))
+	copy(v.RawBytes[headerSize+n:], bb)
+	v.RawBytes = v.RawBytes[:headerSize+n+len(bb)]
 	v.setTag(ValueType_DECIMAL)
+	return nil
 }
 
 // GetBytes returns the bytes field of the receiver. If the tag is not
@@ -507,8 +517,17 @@ func (v Value) GetDecimal() (decimal.Decimal, error) {
 	if tag := v.GetTag(); tag != ValueType_DECIMAL {
 		return decimal.Decimal{}, fmt.Errorf("value type is not %s: %s", ValueType_DECIMAL, tag)
 	}
-	_, d, err := encoding.DecodeDecimalAscending(v.dataBytes())
-	return d, err
+	data := v.dataBytes()
+	i, n := binary.Varint(data)
+	if n <= 0 {
+		return decimal.Decimal{}, fmt.Errorf("int64 varint decoding failed: %d", n)
+	}
+	bi := new(big.Int)
+	err := bi.GobDecode(data[n:])
+	if err != nil {
+		return decimal.Decimal{}, err
+	}
+	return decimal.NewFromBigInt(bi, int32(i)), nil
 }
 
 // GetTimeseries decodes an InternalTimeSeriesData value from the bytes

roachpb/data_test.go

@@ -25,6 +25,7 @@ import (
 
 	"github.com/cockroachdb/cockroach/util"
 	"github.com/cockroachdb/cockroach/util/uuid"
+	"github.com/cockroachdb/decimal"
 )
 
 // TestKeyNext tests that the method for creating lexicographic
@@ -297,14 +298,30 @@ func TestSetGetChecked(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	v.SetFloat(1.1)
-	if _, err := v.GetFloat(); err != nil {
+	f := 1.1
+	v.SetFloat(f)
+	if r, err := v.GetFloat(); err != nil {
 		t.Fatal(err)
+	} else if f != r {
+		t.Errorf("set %f on a value and extracted it, expected %f back, but got %f", f, f, r)
 	}
 
-	v.SetInt(1)
-	if _, err := v.GetInt(); err != nil {
+	i := int64(1)
+	v.SetInt(i)
+	if r, err := v.GetInt(); err != nil {
 		t.Fatal(err)
+	} else if i != r {
+		t.Errorf("set %d on a value and extracted it, expected %d back, but got %d", i, i, r)
+	}
+
+	d := decimal.New(11, -1)
+	if err := v.SetDecimal(d); err != nil {
+		t.Fatal(err)
+	}
+	if r, err := v.GetDecimal(); err != nil {
+		t.Fatal(err)
+	} else if !d.Equals(r) {
+		t.Errorf("set %s on a value and extracted it, expected %s back, but got %s", d, d, r)
 	}
 
 	if err := v.SetProto(&Value{}); err != nil {
@@ -324,9 +341,12 @@ func TestSetGetChecked(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	v.SetTime(time.Time{})
-	if _, err := v.GetTime(); err != nil {
+	ti := time.Time{}
+	v.SetTime(ti)
+	if r, err := v.GetTime(); err != nil {
 		t.Fatal(err)
+	} else if !ti.Equal(r) {
+		t.Errorf("set %s on a value and extracted it, expected %s back, but got %s", ti, ti, r)
 	}
 }
 

sql/executor.go

@@ -26,7 +26,6 @@ import (
 	"time"
 
 	"github.com/gogo/protobuf/proto"
-	"github.com/shopspring/decimal"
 
 	"github.com/cockroachdb/cockroach/client"
 	"github.com/cockroachdb/cockroach/config"
@@ -38,6 +37,7 @@ import (
 	"github.com/cockroachdb/cockroach/util/metric"
 	"github.com/cockroachdb/cockroach/util/retry"
 	"github.com/cockroachdb/cockroach/util/stop"
+	"github.com/cockroachdb/decimal"
 )
 
 var testingWaitForMetadata bool

sql/group.go

@@ -26,7 +26,7 @@ import (
 	"github.com/cockroachdb/cockroach/util"
 	"github.com/cockroachdb/cockroach/util/encoding"
 	"github.com/cockroachdb/cockroach/util/log"
-	"github.com/shopspring/decimal"
+	"github.com/cockroachdb/decimal"
 )
 
 var aggregates = map[string]func() aggregateImpl{