Use dbversion as 5.7.0 when failing to retrive using query or parsing…

… the query output

src/metrics_parse.go

@@ -62,7 +62,9 @@ func asValue(value string) interface{} {
 func getRawData(db dataSource) (map[string]interface{}, map[string]interface{}, string, error) {
 	dbVersion, err := collectDBVersion(db)
 	if err != nil {
-		return nil, nil, "", fmt.Errorf("metrics collection failed: error collecting version number: %w", err)
+		log.Warn(err.Error())
+		log.Warn("Assuming the mysql version to be less than 8.0 and proceeding further")
+		dbVersion = "5.7.0"
 	}
 
 	inventory, err := db.query(inventoryQuery)

src/metrics_parse_test.go

@@ -77,3 +77,31 @@ func TestExtractSanitizedVersion(t *testing.T) {
 		})
 	}
 }
+
+func TestGetRawDataWithoutDBVersion(t *testing.T) {
+	database := testdb{
+		inventory: map[string]interface{}{
+			"key_cache_block_size": 10,
+			"key_buffer_size":      10,
+			"version_comment":      "mysql",
+			"version":              "5.7.0",
+		},
+		metrics: map[string]interface{}{},
+		replica: map[string]interface{}{},
+		version: map[string]interface{}{},
+	}
+	inventory, metrics, dbVersion, err := getRawData(database)
+	assert.Equal(t, "5.7.0", dbVersion)
+	if err != nil {
+		t.Error()
+	}
+	if metrics == nil {
+		t.Error()
+	}
+	if inventory == nil {
+		t.Error()
+	}
+	if dbVersion == "" {
+		t.Error()
+	}
+}