slave_status.patch

diff --git a/collector/slave_status.go b/collector/slave_status.go
index e343258..1fea965 100644
--- a/collector/slave_status.go
+++ b/collector/slave_status.go
@@ -18,7 +18,6 @@ package collector
 import (
 	"context"
 	"database/sql"
-	"fmt"
 	"strings"
 
 	"github.com/go-kit/kit/log"
@@ -30,8 +29,16 @@ const (
 	slaveStatus = "slave_status"
 )
 
-var slaveStatusQueries = [2]string{"SHOW ALL SLAVES STATUS", "SHOW SLAVE STATUS"}
-var slaveStatusQuerySuffixes = [3]string{" NONBLOCKING", " NOLOCK", ""}
+var slaveStatusQueries = [4]string{
+	// Only valid for Percona
+	"SHOW SLAVE STATUS NONBLOCKING",
+	"SHOW SLAVE STATUS NOLOCK",
+	// Only valid for MariaDB
+	"SHOW ALL SLAVE STATUS",
+	// Valid for all
+	"SHOW SLAVE STATUS",
+}
+var slaveStatusQueryIndex = len(slaveStatusQueries)
 
 func columnIndex(slaveCols []string, colName string) int {
 	for idx := range slaveCols {
@@ -74,19 +81,18 @@ func (ScrapeSlaveStatus) Scrape(ctx context.Context, db *sql.DB, ch chan<- prome
 		slaveStatusRows *sql.Rows
 		err             error
 	)
-	// Try the both syntax for MySQL/Percona and MariaDB
-	for _, query := range slaveStatusQueries {
+	// Try the syntax for Percona, MariaDB, and MySQL
+	// and cache the index of the successful query.
+	if slaveStatusQueryIndex < len(slaveStatusQueries) {
+		query := slaveStatusQueries[slaveStatusQueryIndex]
 		slaveStatusRows, err = db.QueryContext(ctx, query)
-		if err != nil { // MySQL/Percona
-			// Leverage lock-free SHOW SLAVE STATUS by guessing the right suffix
-			for _, suffix := range slaveStatusQuerySuffixes {
-				slaveStatusRows, err = db.QueryContext(ctx, fmt.Sprint(query, suffix))
-				if err == nil {
-					break
-				}
+	} else {
+		for i, query := range slaveStatusQueries {
+			slaveStatusRows, err = db.QueryContext(ctx, query)
+			if err == nil {
+				slaveStatusQueryIndex = i
+				break
 			}
-		} else { // MariaDB
-			break
 		}
 	}
 	if err != nil {