sql/pgwire: change formatting of floating point infinity values

Postgres drivers such as JDBC rely on infinite values to be formatted as full words in order to be able to parse the value. Release note (sql change): Floating point infinity values are now formatted as `Infinity` (or `-Infinity` if negative). This is for compatibility with Postgres
cockroachdb · May 11, 2021 · a4a8e23 · a4a8e23
1 parent 97e3a2e
commit a4a8e23
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Showing 3 changed files with 45 additions and 6 deletions.
diff --git a/pkg/cmd/generate-binary/main.go b/pkg/cmd/generate-binary/main.go
@@ -213,8 +213,8 @@ var inputs = map[string][]string{
 		// float encodings. These deviations are still correct, and it's not worth
 		// special casing them into the code, so they are commented out here.
 		//"NaN",
-		//"Inf",
-		//"-Inf",
+		"Inf",
+		"-Inf",
 		"-000.000",
 		"-0000021234.23246346000000",
 		"-1.2",
@@ -234,8 +234,8 @@ var inputs = map[string][]string{
 		// float encodings. These deviations are still correct, and it's not worth
 		// special casing them into the code, so they are commented out here.
 		//"NaN",
-		//"Inf",
-		//"-Inf",
+		"Inf",
+		"-Inf",
 		"-000.000",
 		"-0000021234.2",
 		"-1.2",

diff --git a/pkg/sql/pgwire/testdata/encodings.json b/pkg/sql/pgwire/testdata/encodings.json
@@ -692,6 +692,20 @@
 		"TextAsBinary": [123, 50, 46, 50, 50, 56, 57, 57, 55, 49, 49, 53, 57, 49, 48, 48, 50, 56, 52, 44, 51, 52, 48, 57, 53, 56, 57, 50, 54, 56, 53, 50, 48, 57, 53, 54, 57, 51, 52, 50, 53, 48, 46, 50, 51, 52, 48, 57, 56, 55, 51, 50, 48, 52, 53, 49, 50, 48, 57, 51, 52, 55, 48, 49, 50, 51, 57, 56, 52, 54, 44, 52, 50, 125],
 		"Binary": [0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 6, 164, 0, 0, 0, 3, 0, 0, 0, 1, 0, 0, 0, 18, 0, 5, 0, 0, 0, 0, 0, 16, 0, 2, 8, 241, 37, 239, 23, 22, 1, 28, 0, 0, 0, 34, 0, 13, 0, 5, 0, 0, 0, 27, 0, 34, 3, 190, 36, 52, 20, 89, 22, 61, 16, 154, 9, 36, 38, 145, 7, 253, 4, 185, 13, 142, 4, 215, 33, 12, 0, 0, 0, 10, 0, 1, 0, 0, 0, 0, 0, 0, 0, 42]
 	},
+	{
+		"SQL": "'Inf'::float4",
+		"Oid": 700,
+		"Text": "Infinity",
+		"TextAsBinary": [73, 110, 102, 105, 110, 105, 116, 121],
+		"Binary": [127, 128, 0, 0]
+	},
+	{
+		"SQL": "'-Inf'::float4",
+		"Oid": 700,
+		"Text": "-Infinity",
+		"TextAsBinary": [45, 73, 110, 102, 105, 110, 105, 116, 121],
+		"Binary": [255, 128, 0, 0]
+	},
 	{
 		"SQL": "'-000.000'::float4",
 		"Oid": 700,
@@ -755,6 +769,20 @@
 		"TextAsBinary": [49, 46, 52, 48, 49, 51, 101, 45, 52, 53],
 		"Binary": [0, 0, 0, 1]
 	},
+	{
+		"SQL": "'Inf'::float8",
+		"Oid": 701,
+		"Text": "Infinity",
+		"TextAsBinary": [73, 110, 102, 105, 110, 105, 116, 121],
+		"Binary": [127, 240, 0, 0, 0, 0, 0, 0]
+	},
+	{
+		"SQL": "'-Inf'::float8",
+		"Oid": 701,
+		"Text": "-Infinity",
+		"TextAsBinary": [45, 73, 110, 102, 105, 110, 105, 116, 121],
+		"Binary": [255, 240, 0, 0, 0, 0, 0, 0]
+	},
 	{
 		"SQL": "'-000.000'::float8",
 		"Oid": 701,

diff --git a/pkg/sql/pgwire/types.go b/pkg/sql/pgwire/types.go
@@ -98,8 +98,19 @@ func (b *writeBuffer) writeTextDatum(
 		b.write(s)
 
 	case *tree.DFloat:
-		// Start at offset 4 because `putInt32` clobbers the first 4 bytes.
-		s := strconv.AppendFloat(b.putbuf[4:4], float64(*v), 'g', conv.GetFloatPrec(), 64)
+		fl := float64(*v)
+		var s []byte
+		// PostgreSQL supports 'Inf' as a valid literal for the floating point
+		// special value Infinity, therefore handling the special cases for them.
+		// (https://github.com/cockroachdb/cockroach/issues/62601)
+		if math.IsInf(fl, 1) {
+			s = []byte("Infinity")
+		} else if math.IsInf(fl, -1) {
+			s = []byte("-Infinity")
+		} else {
+			// Start at offset 4 because `putInt32` clobbers the first 4 bytes.
+			s = strconv.AppendFloat(b.putbuf[4:4], fl, 'g', conv.GetFloatPrec(), 64)
+		}
 		b.putInt32(int32(len(s)))
 		b.write(s)