logictest: introduce a separate matcher for floats

This commit adds another type annotation `F` intended to be used for
floating point numbers which have a separate matcher that allows for
some deviation in the precision. Namely, the matcher checks that the
expected and the actual numbers match in 15 significant decimal
digits. Note that I think the matching algorithm introduces some
rounding errors, so it might not work perfectly in all scenarios, yet it
should be good enough in rare test cases when we need it.

Release note: None

pkg/sql/logictest/logic.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"go/build"
 	"io"
+	"math"
 	"math/rand"
 	"net/url"
 	"os"
@@ -163,7 +164,9 @@ import (
 //      - T for text; also used for various types which get converted
 //        to string (arrays, timestamps, etc.).
 //      - I for integer
-//      - R for floating point or decimal
+//      - F for floating point (matches 15 significant decimal digits,
+//        https://www.postgresql.org/docs/9.0/datatype-numeric.html)
+//      - R for decimal
 //      - B for boolean
 //      - O for oid
 //
@@ -2497,11 +2500,11 @@ func (t *logicTest) execQuery(query logicQuery) error {
 								query.pos, i, val, val,
 							)
 						}
-					case 'R':
+					case 'F', 'R':
 						if valT != reflect.Float64 && valT != reflect.Slice {
 							if *flexTypes && (valT == reflect.Int64) {
 								t.signalIgnoredError(
-									fmt.Errorf("result type mismatch: expected R, got %T", val), query.pos, query.sql,
+									fmt.Errorf("result type mismatch: expected F or R, got %T", val), query.pos, query.sql,
 								)
 								return nil
 							}
@@ -2583,7 +2586,14 @@ func (t *logicTest) execQuery(query logicQuery) error {
 			return fmt.Errorf("%s: expected %d results, but found %d", query.pos, query.expectedValues, n)
 		}
 		if query.expectedHash != hash {
-			return fmt.Errorf("%s: expected %s, but found %s", query.pos, query.expectedHash, hash)
+			var suffix string
+			for _, colT := range query.colTypes {
+				if colT == 'F' {
+					suffix = "\tthis might be due to floating numbers precision deviation"
+					break
+				}
+			}
+			return fmt.Errorf("%s: expected %s, but found %s%s", query.pos, query.expectedHash, hash, suffix)
 		}
 	}
 
@@ -2613,25 +2623,47 @@ func (t *logicTest) execQuery(query logicQuery) error {
 		return nil
 	}
 
-	if query.checkResults && !reflect.DeepEqual(query.expectedResults, actualResults) {
-		var buf bytes.Buffer
-		fmt.Fprintf(&buf, "%s: %s\nexpected:\n", query.pos, query.sql)
-		for _, line := range query.expectedResultsRaw {
-			fmt.Fprintf(&buf, "    %s\n", line)
-		}
-		sortMsg := ""
-		if query.sorter != nil {
-			// We performed an order-insensitive comparison of "actual" vs "expected"
-			// rows by sorting both, but we'll display the error with the expected
-			// rows in the order in which they were put in the file, and the actual
-			// rows in the order in which the query returned them.
-			sortMsg = " -> ignore the following ordering of rows"
+	if query.checkResults {
+		makeError := func() error {
+			var buf bytes.Buffer
+			fmt.Fprintf(&buf, "%s: %s\nexpected:\n", query.pos, query.sql)
+			for _, line := range query.expectedResultsRaw {
+				fmt.Fprintf(&buf, "    %s\n", line)
+			}
+			sortMsg := ""
+			if query.sorter != nil {
+				// We performed an order-insensitive comparison of "actual" vs "expected"
+				// rows by sorting both, but we'll display the error with the expected
+				// rows in the order in which they were put in the file, and the actual
+				// rows in the order in which the query returned them.
+				sortMsg = " -> ignore the following ordering of rows"
+			}
+			fmt.Fprintf(&buf, "but found (query options: %q%s) :\n", query.rawOpts, sortMsg)
+			for _, line := range t.formatValues(actualResultsRaw, query.valsPerLine) {
+				fmt.Fprintf(&buf, "    %s\n", line)
+			}
+			return errors.Newf("%s", buf.String())
 		}
-		fmt.Fprintf(&buf, "but found (query options: %q%s) :\n", query.rawOpts, sortMsg)
-		for _, line := range t.formatValues(actualResultsRaw, query.valsPerLine) {
-			fmt.Fprintf(&buf, "    %s\n", line)
+		if len(query.expectedResults) == 0 || len(actualResults) == 0 {
+			if len(query.expectedResults) != len(actualResults) {
+				return makeError()
+			}
+		} else {
+			for i, colT := range query.colTypes {
+				expected, actual := query.expectedResults[i], actualResults[i]
+				resultMatches := expected == actual
+				if !resultMatches && colT == 'F' {
+					var err error
+					resultMatches, err = floatsMatch(expected, actual)
+					if err != nil {
+						return errors.CombineErrors(makeError(), err)
+					}
+				}
+				if !resultMatches {
+					return makeError()
+				}
+			}
 		}
-		return errors.Newf("%s", buf.String())
 	}
 
 	if query.label != "" {
@@ -2648,6 +2680,70 @@ func (t *logicTest) execQuery(query logicQuery) error {
 	return nil
 }
 
+// floatsMatch returns whether two floating point numbers represented as
+// strings have matching 15 significant decimal digits (this is the precision
+// that Postgres supports for 'double precision' type).
+func floatsMatch(expectedString, actualString string) (bool, error) {
+	expected, err := strconv.ParseFloat(expectedString, 64 /* bitSize */)
+	if err != nil {
+		return false, errors.Wrap(err, "when parsing expected")
+	}
+	actual, err := strconv.ParseFloat(actualString, 64 /* bitSize */)
+	if err != nil {
+		return false, errors.Wrap(err, "when parsing actual")
+	}
+	// Check special values - NaN, +Inf, -Inf, 0.
+	if math.IsNaN(expected) || math.IsNaN(actual) {
+		return math.IsNaN(expected) == math.IsNaN(actual), nil
+	}
+	if math.IsInf(expected, 0 /* sign */) || math.IsInf(actual, 0 /* sign */) {
+		bothNegativeInf := math.IsInf(expected, -1 /* sign */) == math.IsInf(actual, -1 /* sign */)
+		bothPositiveInf := math.IsInf(expected, 1 /* sign */) == math.IsInf(actual, 1 /* sign */)
+		return bothNegativeInf || bothPositiveInf, nil
+	}
+	if expected == 0 || actual == 0 {
+		return expected == actual, nil
+	}
+	// Check that the numbers have the same sign.
+	if expected*actual < 0 {
+		return false, nil
+	}
+	expected = math.Abs(expected)
+	actual = math.Abs(actual)
+	// Check that 15 significant digits match. We do so by normalizing the
+	// numbers and then checking one digit at a time.
+	//
+	// normalize converts f to base * 10**power representation where base is in
+	// [1.0, 10.0) range.
+	normalize := func(f float64) (base float64, power int) {
+		for f >= 10 {
+			f = f / 10
+			power++
+		}
+		for f < 1 {
+			f *= 10
+			power--
+		}
+		return f, power
+	}
+	var expPower, actPower int
+	expected, expPower = normalize(expected)
+	actual, actPower = normalize(actual)
+	if expPower != actPower {
+		return false, nil
+	}
+	for i := 0; i < 15; i++ {
+		expDigit := int(expected)
+		actDigit := int(actual)
+		if expDigit != actDigit {
+			return false, nil
+		}
+		expected -= (expected - float64(expDigit)) * 10
+		actual -= (actual - float64(actDigit)) * 10
+	}
+	return true, nil
+}
+
 func (t *logicTest) formatValues(vals []string, valsPerLine int) []string {
 	var buf bytes.Buffer
 	tw := tabwriter.NewWriter(&buf, 2, 1, 2, ' ', 0)

pkg/sql/logictest/logic_test.go

@@ -35,3 +35,32 @@ func TestSqlLiteLogic(t *testing.T) {
 	defer leaktest.AfterTest(t)()
 	RunSQLLiteLogicTest(t, "" /* configOverride */)
 }
+
+// TestFloatsMatch is a unit test for floatsMatch() function.
+func TestFloatsMatch(t *testing.T) {
+	defer leaktest.AfterTest(t)()
+	for _, tc := range []struct {
+		f1, f2 string
+		match  bool
+	}{
+		{f1: "NaN", f2: "+Inf", match: false},
+		{f1: "+Inf", f2: "+Inf", match: true},
+		{f1: "NaN", f2: "NaN", match: true},
+		{f1: "+Inf", f2: "-Inf", match: false},
+		{f1: "-0.0", f2: "0.0", match: true},
+		{f1: "0.0", f2: "NaN", match: false},
+		{f1: "123.45", f2: "12.345", match: false},
+		{f1: "0.1234567890123456", f2: "0.1234567890123455", match: true},
+		{f1: "0.1234567890123456", f2: "0.1234567890123457", match: true},
+		{f1: "-0.1234567890123456", f2: "0.1234567890123456", match: false},
+		{f1: "-0.1234567890123456", f2: "-0.1234567890123455", match: true},
+	} {
+		match, err := floatsMatch(tc.f1, tc.f2)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if match != tc.match {
+			t.Fatalf("wrong result on %v", tc)
+		}
+	}
+}

pkg/sql/logictest/testdata/logic_test/crdb_internal

@@ -144,7 +144,7 @@ SELECT * FROM crdb_internal.leases WHERE node_id < 0
 ----
 node_id  table_id  name  parent_id  expiration  deleted
 
-query ITTTTIIITFFFFFFFFFFFFFFFFF colnames
+query ITTTTIIITRRRRRRRRRRRRRRRRR colnames
 SELECT * FROM crdb_internal.node_statement_statistics WHERE node_id < 0
 ----
 node_id  application_name  flags  key  anonymized  count  first_attempt_count  max_retries  last_error  rows_avg  rows_var  parse_lat_avg  parse_lat_var  plan_lat_avg  plan_lat_var  run_lat_avg  run_lat_var  service_lat_avg  service_lat_var  overhead_lat_avg  overhead_lat_var  bytes_read_avg  bytes_read_var  rows_read_avg  rows_read_var  implicit_txn

pkg/sql/logictest/testdata/logic_test/float

@@ -132,3 +132,10 @@ DROP TABLE vals
 
 statement ok
 RESET extra_float_digits
+
+# Test that floating point numbers are compared with 15 decimal digits
+# precision.
+query FFF
+SELECT -0.1234567890123456, 123456789012345.6, 1234567.890123456
+----
+-0.1234567890123457 123456789012345.7 1234567.890123457

pkg/sql/logictest/testdata/logic_test/select

@@ -688,7 +688,7 @@ CREATE TABLE wide (id INT4 NOT NULL, a INT4, b VARCHAR(255), c INT4, d VARCHAR(2
 statement ok
 INSERT INTO wide(id, n) VALUES(0, 10)
 
-query IITITTITTTTIFFI
+query IITITTITTTTIRRI
 SELECT * FROM wide
 ----
 0  NULL  NULL  NULL  NULL  NULL  NULL  NULL  NULL  NULL  NULL  NULL  NULL  NULL  10