introduces ByteSortable method in Revision

This helps determine if the string representation
of the revision is byte-sortable. This helps
being able to determine if a revision can be
serialized to databases that rely on byte-sorting.

internal/datastore/postgres/revisions.go

@@ -279,6 +279,10 @@ type postgresRevision struct {
 	optionalMetadata       map[string]any
 }
 
+func (pr postgresRevision) ByteSortable() bool {
+	return false
+}
+
 func (pr postgresRevision) Equal(rhsRaw datastore.Revision) bool {
 	rhs, ok := rhsRaw.(postgresRevision)
 	return ok && pr.snapshot.Equal(rhs.snapshot)

internal/datastore/revisions/commonrevision_test.go

@@ -1,6 +1,8 @@
 package revisions
 
 import (
+	"bytes"
+	"sort"
 	"strings"
 	"testing"
 
@@ -246,3 +248,84 @@ func TestHLCRevisionParsing(t *testing.T) {
 		})
 	}
 }
+
+func TestRevisionByteSortable(t *testing.T) {
+	tcs := []struct {
+		left      string
+		right     string
+		leftFirst bool
+	}{
+		{
+			"1",
+			"2",
+			true,
+		},
+		{
+			"2",
+			"1",
+			false,
+		},
+		{
+			"1",
+			"1",
+			true,
+		},
+		{
+			"1.0000000004",
+			"1",
+			false,
+		},
+		{
+			"1",
+			"1.0000000004",
+			true,
+		},
+		{
+			"1.0000000004",
+			"1.0000000004",
+			true,
+		},
+		{
+			"1.1000000000",
+			"1.0000000001",
+			false,
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.left+"_"+tc.right, func(t *testing.T) {
+			for kind, supportsDecimals := range kinds {
+				t.Run(string(kind), func(t *testing.T) {
+					if !supportsDecimals && strings.Contains(tc.left, ".") {
+						t.Skip("does not support decimals")
+					}
+
+					if !supportsDecimals && strings.Contains(tc.right, ".") {
+						t.Skip("does not support decimals")
+					}
+					parser := RevisionParser(kind)
+
+					leftRev, err := parser(tc.left)
+					require.NoError(t, err)
+
+					rightRev, err := parser(tc.right)
+					require.NoError(t, err)
+
+					if !leftRev.ByteSortable() || !rightRev.ByteSortable() {
+						t.Skip("does not support byt sorting")
+					}
+
+					toSort := []string{leftRev.String(), rightRev.String()}
+					sort.Strings(toSort)
+					if tc.leftFirst {
+						require.Equal(t, leftRev.String(), toSort[0])
+						require.Equal(t, 0, bytes.Compare([]byte(leftRev.String()), []byte(toSort[0])))
+					} else {
+						require.Equal(t, rightRev.String(), toSort[0])
+						require.Equal(t, 0, bytes.Compare([]byte(rightRev.String()), []byte(toSort[0])))
+					}
+				})
+			}
+		})
+	}
+}

internal/datastore/revisions/hlcrevision.go

@@ -98,6 +98,10 @@ func NewHLCForTime(time time.Time) HLCRevision {
 	return HLCRevision{time.UnixNano(), logicalClockOffset}
 }
 
+func (hlc HLCRevision) ByteSortable() bool {
+	return true
+}
+
 func (hlc HLCRevision) Equal(rhs datastore.Revision) bool {
 	if rhs == datastore.NoRevision {
 		rhs = zeroHLC

internal/datastore/revisions/timestamprevision.go

@@ -33,6 +33,10 @@ func parseTimestampRevisionString(revisionStr string) (rev datastore.Revision, e
 	return TimestampRevision(parsed), nil
 }
 
+func (ir TimestampRevision) ByteSortable() bool {
+	return true
+}
+
 func (ir TimestampRevision) Equal(rhs datastore.Revision) bool {
 	if rhs == datastore.NoRevision {
 		rhs = zeroTimestampRevision

internal/datastore/revisions/txidrevision.go

@@ -27,6 +27,10 @@ func parseTransactionIDRevisionString(revisionStr string) (rev datastore.Revisio
 	return TransactionIDRevision(parsed), nil
 }
 
+func (ir TransactionIDRevision) ByteSortable() bool {
+	return true
+}
+
 func (ir TransactionIDRevision) Equal(rhs datastore.Revision) bool {
 	if rhs == datastore.NoRevision {
 		rhs = zeroTransactionIDRevision

pkg/datastore/datastore.go

@@ -817,10 +817,17 @@ type Revision interface {
 
 	// LessThan returns whether the receiver is probably less than the right hand side.
 	LessThan(Revision) bool
+
+	// ByteSortable returns true if the string representation of the Revision is byte sortable, false otherwise.
+	ByteSortable() bool
 }
 
 type nilRevision struct{}
 
+func (nilRevision) ByteSortable() bool {
+	return false
+}
+
 func (nilRevision) Equal(rhs Revision) bool {
 	return rhs == NoRevision
 }