get pg version revisited

stat_wal_receiver.go

@@ -3,7 +3,6 @@ package pgstats
 import (
 	"database/sql"
 	"github.com/lib/pq"
-	"github.com/pkg/errors"
 )
 
 // PgStatWalReceiverView represents content of pg_stat_wal_receiver view
@@ -49,13 +48,11 @@ func (s *PgStats) fetchWalReceiver() (PgStatWalReceiverView, error) {
 	if err != nil {
 		return PgStatWalReceiverView{}, err
 	}
-	switch version {
-	case "11":
-		return s.fetchWalReceiver11()
-	case "10":
+	if version < 11 {
 		return s.fetchWalReceiver10()
+	} else {
+		return s.fetchWalReceiver11()
 	}
-	return PgStatWalReceiverView{}, errors.New("Unsupported PG version " + version)
 }
 
 func (s *PgStats) fetchWalReceiver11() (PgStatWalReceiverView, error) {

version.go

@@ -3,28 +3,32 @@ package pgstats
 import (
 	"github.com/pkg/errors"
 	"regexp"
+	"strconv"
 )
 
-func (s *PgStats) getPgVersion() (string, error) {
+func (s *PgStats) getPgVersion() (float64, error) {
 	db := s.conn.db
 	query := "show server_version;"
 	row := db.QueryRow(query)
 	version := new(string)
-	err := row.Scan(&version)
-	if err != nil {
-		return "", err
-	}
-	v := extractMajorVersion(*version)
-	if v == "" {
-		err = errors.New("Regex error")
+	if err := row.Scan(&version); err != nil {
+		return 0, err
 	}
-	return v, err
+	return extractMajorVersion(*version)
 }
 
-func extractMajorVersion(fullVersion string) string {
+func extractMajorVersion(fullVersion string) (float64, error) {
 	r, err := regexp.Compile(`(^9\.\d)|(^\d\d)`)
 	if err != nil {
-		return ""
+		return 0, errors.New("Regex compile error")
+	}
+	strv := r.FindString(fullVersion)
+	if strv == "" {
+		return 0, errors.New("Regex parse error")
+	}
+	version, err := strconv.ParseFloat(strv, 64)
+	if err != nil {
+		return 0, err
 	}
-	return r.FindString(fullVersion)
+	return version, nil
 }

version_test.go

@@ -4,20 +4,23 @@ import "testing"
 
 var versionTests = []struct {
 	input  string
-	output string
+	output float64
 }{
-	{"11.3", "11"},
-	{"10.12", "10"},
-	{"9.6.13", "9.6"},
-	{"9.5.17", "9.5"},
-	{"9.4.22", "9.4"},
+	{"11.3", 11},
+	{"10.12", 10},
+	{"9.6.13", 9.6},
+	{"9.5.17", 9.5},
+	{"9.4.22", 9.4},
 }
 
 func TestExtractMajorVersion(t *testing.T) {
 	for _, tt := range versionTests {
-		actual := extractMajorVersion(tt.input)
+		actual, err := extractMajorVersion(tt.input)
+		if err != nil {
+			t.Error(err)
+		}
 		if actual != tt.output {
-			t.Errorf("Expected '%s'; actual '%s'", tt.output, actual)
+			t.Errorf("Expected '%f'; actual '%f'", tt.output, actual)
 		}
 	}
 }