From a4a8e2329421767bcecce6ca2179d418d607903f Mon Sep 17 00:00:00 2001
From: Mohammad Aziz <mdaziz067@gmail.com>
Date: Thu, 6 May 2021 08:10:22 +0530
Subject: [PATCH] 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
---
 pkg/cmd/generate-binary/main.go        |  8 ++++----
 pkg/sql/pgwire/testdata/encodings.json | 28 ++++++++++++++++++++++++++
 pkg/sql/pgwire/types.go                | 15 ++++++++++++--
 3 files changed, 45 insertions(+), 6 deletions(-)

diff --git a/pkg/cmd/generate-binary/main.go b/pkg/cmd/generate-binary/main.go
index 4e9d5b0f172d..180f26ca66e5 100644
--- 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
index e1827a2d978c..8fc92ee74347 100644
--- 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
index 0e46e5a8c074..17e1a2595cfa 100644
--- 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)