changefeedccl/schemafeed: add verbose logging to table event filter

This patch adds some verbose logging to the schema feed table event
filter to make it easier to debug missing schema feed events.

Release note: None

Author: andyyang890

pkg/ccl/changefeedccl/changefeed_test.go

@@ -6253,6 +6253,8 @@ func TestChangefeedTruncateOrDrop(t *testing.T) {
 	defer leaktest.AfterTest(t)()
 	defer log.Scope(t).Close(t)
 
+	require.NoError(t, log.SetVModule("table_event_filter=2"))
+
 	assertFailuresCounter := func(t *testing.T, m *Metrics, exp int64) {
 		t.Helper()
 		// If this changefeed is running as a job, we anticipate that it will move

pkg/ccl/changefeedccl/schemafeed/table_event_filter.go

@@ -14,6 +14,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/descpb"
 	"github.com/cockroachdb/cockroach/pkg/sql/schemachanger/scpb"
 	"github.com/cockroachdb/cockroach/pkg/util/intsets"
+	"github.com/cockroachdb/cockroach/pkg/util/log"
 	"github.com/cockroachdb/errors"
 )
 
@@ -123,9 +124,16 @@ type tableEventFilter map[tableEventType]bool
 
 func (filter tableEventFilter) shouldFilter(
 	ctx context.Context, e TableEvent, targets changefeedbase.Targets,
-) (bool, error) {
+) (ok bool, _ error) {
 	et := classifyTableEvent(e)
 
+	if log.V(2) {
+		log.Infof(ctx, "table event %v classified as %v", e, et)
+		defer func() {
+			log.Infof(ctx, "should filter table event %v: %t", e, ok)
+		}()
+	}
+
 	// Truncation events are not ignored and return an error.
 	if et.Contains(tableEventTruncate) {
 		return false, errors.Errorf(`"%s" was truncated`, e.Before.GetName())