Log and ignore the error in reading udfs in schema tracker

go/mysql/fakesqldb/server.go

@@ -592,6 +592,13 @@ func (db *DB) AddQueryPattern(queryPattern string, expectedResult *sqltypes.Resu
 	db.patternData[queryPattern] = exprResult{queryPattern: queryPattern, expr: expr, result: &result}
 }
 
+// RemoveQueryPattern removes a query pattern that was previously added.
+func (db *DB) RemoveQueryPattern(queryPattern string) {
+	db.mu.Lock()
+	defer db.mu.Unlock()
+	delete(db.patternData, queryPattern)
+}
+
 // RejectQueryPattern allows a query pattern to be rejected with an error
 func (db *DB) RejectQueryPattern(queryPattern, error string) {
 	expr := regexp.MustCompile("(?is)^" + queryPattern + "$")

go/vt/logutil/throttled.go

@@ -54,6 +54,11 @@ var (
 	errorDepth   = log.ErrorDepth
 )
 
+// GetLastLogTime gets the last log time for the throttled logger.
+func (tl *ThrottledLogger) GetLastLogTime() time.Time {
+	return tl.lastlogTime
+}
+
 func (tl *ThrottledLogger) log(logF logFunc, format string, v ...any) {
 	now := time.Now()
 

go/vt/vttablet/tabletserver/schema/engine.go

@@ -40,6 +40,7 @@ import (
 	"vitess.io/vitess/go/vt/dbconfigs"
 	"vitess.io/vitess/go/vt/dbconnpool"
 	"vitess.io/vitess/go/vt/log"
+	"vitess.io/vitess/go/vt/logutil"
 	"vitess.io/vitess/go/vt/mysqlctl/tmutils"
 	"vitess.io/vitess/go/vt/schema"
 	"vitess.io/vitess/go/vt/servenv"
@@ -85,9 +86,10 @@ type Engine struct {
 
 	historian *historian
 
-	conns         *connpool.Pool
-	ticks         *timer.Timer
-	reloadTimeout time.Duration
+	conns           *connpool.Pool
+	ticks           *timer.Timer
+	reloadTimeout   time.Duration
+	throttledLogger *logutil.ThrottledLogger
 
 	// dbCreationFailed is for preventing log spam.
 	dbCreationFailed bool
@@ -109,7 +111,8 @@ func NewEngine(env tabletenv.Env) *Engine {
 			Size:        3,
 			IdleTimeout: env.Config().OltpReadPool.IdleTimeout,
 		}),
-		ticks: timer.NewTimer(reloadTime),
+		ticks:           timer.NewTimer(reloadTime),
+		throttledLogger: logutil.NewThrottledLogger("schema-tracker", 1*time.Minute),
 	}
 	se.schemaCopy = env.Config().SignalWhenSchemaChange
 	_ = env.Exporter().NewGaugeDurationFunc("SchemaReloadTime", "vttablet keeps table schemas in its own memory and periodically refreshes it from MySQL. This config controls the reload time.", se.ticks.Interval)
@@ -448,7 +451,7 @@ func (se *Engine) reload(ctx context.Context, includeStats bool) error {
 
 	udfsChanged, err := getChangedUserDefinedFunctions(ctx, conn.Conn, shouldUseDatabase)
 	if err != nil {
-		return err
+		se.throttledLogger.Errorf("error in getting changed UDFs: %v", err)
 	}
 
 	rec := concurrency.AllErrorRecorder{}

go/vt/vttablet/tabletserver/schema/engine_test.go

@@ -1331,7 +1331,8 @@ func TestEngineReload(t *testing.T) {
 	}
 
 	// adding query pattern for udfs
-	db.AddQueryPattern("SELECT name.*", &sqltypes.Result{})
+	udfQueryPattern := "SELECT name.*"
+	db.AddQueryPattern(udfQueryPattern, &sqltypes.Result{})
 
 	// Verify the list of created, altered and dropped tables seen.
 	se.RegisterNotifier("test", func(full map[string]*Table, created, altered, dropped []*Table, _ bool) {
@@ -1344,6 +1345,16 @@ func TestEngineReload(t *testing.T) {
 	err = se.reload(context.Background(), false)
 	require.NoError(t, err)
 	require.NoError(t, db.LastError())
+	require.Zero(t, se.throttledLogger.GetLastLogTime())
+
+	// Now if we remove the query pattern for udfs, schema engine shouldn't fail.
+	// Instead we should see a log message with the error.
+	db.RemoveQueryPattern(udfQueryPattern)
+	se.UnregisterNotifier("test")
+	err = se.reload(context.Background(), false)
+	require.NoError(t, err)
+	// Check for the udf error being logged. The last log time should be less than a second.
+	require.Less(t, time.Since(se.throttledLogger.GetLastLogTime()), 1*time.Second)
 }
 
 // TestEngineReload tests the vreplication specific GetTableForPos function to ensure