do not cascade DROP commands always

src/backend/distributed/commands/utility_hook.c

@@ -70,6 +70,8 @@ static bool shouldInvalidateForeignKeyGraph = false;
 static int activeAlterTables = 0;
 static int activeDropSchemaOrDBs = 0;
 
+/* assume always cascading for the direct usage of master_drop_all_shards */
+bool isDropCommandCascading = true;
 
 /* Local functions forward declarations for helper functions */
 static void ExecuteDistributedDDLJob(DDLJob *ddlJob);
@@ -455,6 +457,14 @@ multi_ProcessUtility(PlannedStmt *pstmt,
 		StopMaintenanceDaemon(MyDatabaseId);
 	}
 
+	if (IsA(parsetree, DropStmt))
+	{
+		DropStmt *dropStmt = castNode(DropStmt, parsetree);
+
+		/* to set DROP behaviors of the DROP shard commands accordingly */
+		isDropCommandCascading = (dropStmt->behavior == DROP_CASCADE);
+	}
+
 	pstmt->utilityStmt = parsetree;
 
 	PG_TRY();
@@ -487,6 +497,9 @@ multi_ProcessUtility(PlannedStmt *pstmt,
 		standard_ProcessUtility(pstmt, queryString, context,
 								params, queryEnv, dest, completionTag);
 
+		/* assume always cascading for the direct usage of master_drop_all_shards */
+		isDropCommandCascading = true;
+
 		/*
 		 * if we are running ALTER EXTENSION citus UPDATE (to "<version>") command, we may need
 		 * to mark existing objects as distributed depending on the "version" parameter if

src/backend/distributed/master/master_delete_protocol.c

@@ -609,6 +609,11 @@ CreateDropShardPlacementCommand(const char *schemaName, const char *shardRelatio
 		Assert(false);
 	}
 
+	if (isDropCommandCascading)
+	{
+		appendStringInfo(workerDropQuery, " CASCADE");
+	}
+
 	return workerDropQuery->data;
 }
 

src/include/distributed/commands/utility_hook.h

@@ -32,6 +32,9 @@ extern bool EnableDependencyCreation;
 extern bool EnableCreateTypePropagation;
 extern bool EnableAlterRolePropagation;
 
+/* whether current DROP command is cascading or not */
+extern bool isDropCommandCascading;
+
 /*
  * A DDLJob encapsulates the remote tasks and commands needed to process all or
  * part of a distributed DDL command. It hold the distributed relation's oid,

src/include/distributed/master_protocol.h

@@ -67,8 +67,8 @@
 #define SHARD_RANGE_QUERY "SELECT min(%s), max(%s) FROM %s"
 #define SHARD_TABLE_SIZE_QUERY "SELECT pg_table_size(%s)"
 #define SHARD_CSTORE_TABLE_SIZE_QUERY "SELECT cstore_table_size(%s)"
-#define DROP_REGULAR_TABLE_COMMAND "DROP TABLE IF EXISTS %s CASCADE"
-#define DROP_FOREIGN_TABLE_COMMAND "DROP FOREIGN TABLE IF EXISTS %s CASCADE"
+#define DROP_REGULAR_TABLE_COMMAND "DROP TABLE IF EXISTS %s"
+#define DROP_FOREIGN_TABLE_COMMAND "DROP FOREIGN TABLE IF EXISTS %s"
 #define CREATE_SCHEMA_COMMAND "CREATE SCHEMA IF NOT EXISTS %s AUTHORIZATION %s"
 
 /* Enumeration that defines the shard placement policy to use while staging */