diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c
index 78b9ca48c7..05b9c41e88 100644
--- a/src/backend/replication/logical/decode.c
+++ b/src/backend/replication/logical/decode.c
@@ -629,11 +629,13 @@ DecodeCommit(LogicalDecodingContext *ctx, XLogRecordBuffer *buf,
 
 	/*
 	 * If the COMMIT record has invalidation messages, it could have catalog
-	 * changes. We check if it's in the list of the initial running transactions
-	 * and then mark it as containing catalog change.
+	 * changes. It is possible that we didn't mark this transaction as
+	 * containing catalog changes when the decoding starts from a commit record
+	 * without decoding the transaction's other changes. So, we ensure to mark
+	 * such transactions as containing catalog change.
 	 *
 	 * This must be done before SnapBuildCommitTxn() so that we can include
-	 * catalog change transactions to the historic snapshot.
+	 * these transactions in the historic snapshot.
 	 */
 	if (parsed->xinfo & XACT_XINFO_HAS_INVALS)
 		SnapBuildInitialXactSetCatalogChanges(ctx->snapshot_builder,
diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index 2585922dad..3cdee00b9b 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -253,10 +253,10 @@ static bool ExportInProgress = false;
 /*
  * Array of transactions and subtransactions that were running when
  * the xl_running_xacts record that we decoded first was written.
- * The array is sorted in xidComparator order. Xids are only removed
- * from the array when decoding xl_running_xacts record, and then
- * the array eventually becomes an empty. This array is allocated in
- * builder->context so its lifetime is the same as the snapshot builder.
+ * The array is sorted in xidComparator order. We remove Xids from
+ * this array when they become old enough to matter. This array is
+ * allocated in builder->context so its lifetime is the same as the
+ * snapshot builder.
  *
  * We rely on HEAP2_NEW_CID records and XACT_INVALIDATIONS to know
  * if the transaction has changed the catalog, and that information
@@ -2095,8 +2095,9 @@ CheckPointSnapBuild(void)
 }
 
 /*
- * If the given xid is in the list of the initial running xacts, we mark both it
- * and its subtransactions as containing catalog changes if not yet.
+ * If the given xid is in the list of the initial running xacts, we mark the
+ * transaction and its subtransactions as containing catalog changes. See
+ * comments
  */
 void
 SnapBuildInitialXactSetCatalogChanges(SnapBuild *builder, TransactionId xid,