fix canal.GetMasterPos() for mariadb (#1030)

* fix canal.GetMasterPos() for mariadb

* add getShowBinaryLogQuery

* add test

* improve docs

---------

Co-authored-by: Guillem <[email protected]>

Author: alarbada

canal/sync.go

@@ -324,13 +324,34 @@ func (c *Canal) WaitUntilPos(pos mysql.Position, timeout time.Duration) error {
 	}
 }
 
-func (c *Canal) GetMasterPos() (mysql.Position, error) {
-	showBinlogStatus := "SHOW BINARY LOG STATUS"
-	if eq, err := c.conn.CompareServerVersion("8.4.0"); (err == nil) && (eq < 0) {
-		showBinlogStatus = "SHOW MASTER STATUS"
+// getShowBinaryLogQuery returns the correct SQL statement to query binlog status
+// for the given database flavor and server version.
+//
+// Sources:
+//
+//	MySQL:   https://dev.mysql.com/doc/relnotes/mysql/8.4/en/news-8-4-0.html
+//	MariaDB: https://mariadb.com/kb/en/show-binlog-status
+func getShowBinaryLogQuery(flavor, serverVersion string) string {
+	switch flavor {
+	case mysql.MariaDBFlavor:
+		eq, err := mysql.CompareServerVersions(serverVersion, "10.5.2")
+		if (err == nil) && (eq >= 0) {
+			return "SHOW BINLOG STATUS"
+		}
+	case mysql.MySQLFlavor:
+		eq, err := mysql.CompareServerVersions(serverVersion, "8.4.0")
+		if (err == nil) && (eq >= 0) {
+			return "SHOW BINARY LOG STATUS"
+		}
 	}
 
-	rr, err := c.Execute(showBinlogStatus)
+	return "SHOW MASTER STATUS"
+}
+
+func (c *Canal) GetMasterPos() (mysql.Position, error) {
+	query := getShowBinaryLogQuery(c.cfg.Flavor, c.conn.GetServerVersion())
+
+	rr, err := c.Execute(query)
 	if err != nil {
 		return mysql.Position{}, errors.Trace(err)
 	}

canal/sync_test.go

@@ -0,0 +1,31 @@
+package canal
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestGetShowBinaryLogQuery(t *testing.T) {
+	tests := []struct {
+		flavor        string
+		serverVersion string
+		expected      string
+	}{
+		{flavor: "mariadb", serverVersion: "10.5.2", expected: "SHOW BINLOG STATUS"},
+		{flavor: "mariadb", serverVersion: "10.6.0", expected: "SHOW BINLOG STATUS"},
+		{flavor: "mariadb", serverVersion: "10.4.0", expected: "SHOW MASTER STATUS"},
+		{flavor: "mysql", serverVersion: "8.4.0", expected: "SHOW BINARY LOG STATUS"},
+		{flavor: "mysql", serverVersion: "8.4.1", expected: "SHOW BINARY LOG STATUS"},
+		{flavor: "mysql", serverVersion: "8.0.33", expected: "SHOW MASTER STATUS"},
+		{flavor: "mysql", serverVersion: "5.7.41", expected: "SHOW MASTER STATUS"},
+		{flavor: "other", serverVersion: "1.0.0", expected: "SHOW MASTER STATUS"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.flavor+"_"+tt.serverVersion, func(t *testing.T) {
+			got := getShowBinaryLogQuery(tt.flavor, tt.serverVersion)
+			require.Equal(t, tt.expected, got)
+		})
+	}
+}