Adds first commit

src/backend/distributed/Makefile

@@ -18,7 +18,7 @@ generated_downgrade_sql_files += $(patsubst %,$(citus_abs_srcdir)/build/sql/%,$(
 DATA_built = $(generated_sql_files)
 
 # directories with source files
-SUBDIRS = . commands connection ddl deparser executor metadata operations planner progress relay safeclib shardsplit test transaction utils worker clock
+SUBDIRS = . commands connection database ddl deparser executor metadata operations planner progress relay safeclib shardsplit test transaction utils worker clock
 # enterprise modules
 SUBDIRS += replication
 

src/backend/distributed/commands/database.c

@@ -19,6 +19,7 @@
 #include "miscadmin.h"
 #include "nodes/parsenodes.h"
 #include "utils/syscache.h"
+#include "utils/builtins.h"
 
 #include "distributed/commands.h"
 #include "distributed/commands/utility_hook.h"
@@ -28,13 +29,42 @@
 #include "distributed/multi_executor.h"
 #include "distributed/relation_access_tracking.h"
 #include "distributed/worker_transaction.h"
+#include "distributed/deparser.h"
+#include "distributed/worker_protocol.h"
+#include "distributed/metadata/distobject.h"
+#include "distributed/database/database_sharding.h"
+#include "distributed/deparse_shard_query.h"
+
+
+
+/* macros to add DefElems to a list  */
+#define DEFELEM_ADD_STRING(options, key, value) { \
+		DefElem *elem = makeDefElem(key, (Node *) makeString(value), -1); \
+		options = lappend(options, elem); \
+}
+
+#define DEFELEM_ADD_BOOL(options, key, value) { \
+		DefElem *elem = makeDefElem(key, (Node *) makeBoolean(value), -1); \
+		options = lappend(options, elem); \
+}
+
+#define DEFELEM_ADD_INT(options, key, value) { \
+		DefElem *elem = makeDefElem(key, (Node *) makeInteger(value), -1); \
+		options = lappend(options, elem); \
+}
 
 static AlterOwnerStmt * RecreateAlterDatabaseOwnerStmt(Oid databaseOid);
+
+static List * CreateDDLTaskList(char *command, List *workerNodeList,
+								bool outsideTransaction);
+
+PG_FUNCTION_INFO_V1(citus_internal_database_command);
 static Oid get_database_owner(Oid db_oid);
 List * PreprocessGrantOnDatabaseStmt(Node *node, const char *queryString,
 									 ProcessUtilityContext processUtilityContext);
 
 /* controlled via GUC */
+bool EnableCreateDatabasePropagation = true;
 bool EnableAlterDatabaseOwner = true;
 
 
@@ -148,6 +178,78 @@ PreprocessGrantOnDatabaseStmt(Node *node, const char *queryString,
 	return NodeDDLTaskList(NON_COORDINATOR_NODES, commands);
 }
 
+/*
+ * citus_internal_database_command is an internal UDF to
+ * create/drop a database in an idempotent maner without
+ * transaction block restrictions.
+ */
+Datum
+citus_internal_database_command(PG_FUNCTION_ARGS)
+{
+	text *commandText = PG_GETARG_TEXT_P(0);
+	char *command = text_to_cstring(commandText);
+	Node *parseTree = ParseTreeNode(command);
+
+	set_config_option("citus.enable_ddl_propagation", "off",
+					  (superuser() ? PGC_SUSET : PGC_USERSET), PGC_S_SESSION,
+					  GUC_ACTION_LOCAL, true, 0, false);
+
+	set_config_option("citus.enable_create_database_propagation", "off",
+					  (superuser() ? PGC_SUSET : PGC_USERSET), PGC_S_SESSION,
+					  GUC_ACTION_LOCAL, true, 0, false);
+
+	if (IsA(parseTree, CreatedbStmt))
+	{
+		CreatedbStmt *stmt = castNode(CreatedbStmt, parseTree);
+
+		bool missingOk = true;
+		Oid databaseOid = get_database_oid(stmt->dbname, missingOk);
+
+		if (!OidIsValid(databaseOid))
+		{
+			createdb(NULL, (CreatedbStmt *) parseTree);
+		}
+		else
+		{
+			/* TODO: check database properties */
+		}
+	}
+	else if (IsA(parseTree, DropdbStmt))
+	{
+		DropdbStmt *stmt = castNode(DropdbStmt, parseTree);
+
+		bool missingOk = true;
+		Oid databaseOid = get_database_oid(stmt->dbname, missingOk);
+
+		if (!OidIsValid(databaseOid))
+		{
+			/* already dropped? */
+		}
+		else
+		{
+			/* remove database from pg_dist_object */
+			ObjectAddress dbAddress = { 0 };
+			ObjectAddressSet(dbAddress, DatabaseRelationId, databaseOid);
+
+			if (IsObjectDistributed(&dbAddress))
+			{
+				UnmarkObjectDistributed(&dbAddress);
+			}
+
+			/* remove database from database shards */
+			DeleteDatabaseShardByDatabaseIdLocally(databaseOid);
+
+			DropDatabase(NULL, (DropdbStmt *) parseTree);
+		}
+	}
+	else
+	{
+		ereport(ERROR, (errmsg("unsupported command type %d", nodeTag(parseTree))));
+	}
+
+	PG_RETURN_VOID();
+}
+
 
 /*
  * PreprocessAlterDatabaseStmt is executed before the statement is applied to the local
@@ -213,6 +315,35 @@ PreprocessAlterDatabaseRefreshCollStmt(Node *node, const char *queryString,
 
 #endif
 
+/*
+ * CreateDDLTaskList creates a task list for running a single DDL command.
+ */
+static List *
+CreateDDLTaskList(char *command, List *workerNodeList, bool outsideTransaction)
+{
+	List *commandList = list_make3(DISABLE_DDL_PROPAGATION,
+								   command,
+								   ENABLE_DDL_PROPAGATION);
+
+	Task *task = CitusMakeNode(Task);
+	task->taskType = DDL_TASK;
+	SetTaskQueryStringList(task, commandList);
+	task->cannotBeExecutedInTransction = outsideTransaction;
+
+	WorkerNode *workerNode = NULL;
+	foreach_ptr(workerNode, workerNodeList)
+	{
+		ShardPlacement *targetPlacement = CitusMakeNode(ShardPlacement);
+		targetPlacement->nodeName = workerNode->workerName;
+		targetPlacement->nodePort = workerNode->workerPort;
+		targetPlacement->groupId = workerNode->groupId;
+		task->taskPlacementList = lappend(task->taskPlacementList,
+										  targetPlacement);
+	}
+
+	return list_make1(task);
+}
+
 
 /*
  * PreprocessAlterDatabaseSetStmt is executed before the statement is applied to the local
@@ -242,3 +373,111 @@ PreprocessAlterDatabaseSetStmt(Node *node, const char *queryString,
 
 	return NodeDDLTaskList(NON_COORDINATOR_NODES, commands);
 }
+
+
+/*
+ * PostprocessCreatedbStmt creates the plan to synchronize CREATE DATABASE
+ * across nodes. We use the cannotBeExecutedInTransction option to avoid
+ * u* sending transaction blocks.
+ */
+List *
+PostprocessCreateDatabaseStmt(Node *node, const char *queryString)
+{
+	if (!EnableCreateDatabasePropagation || !ShouldPropagate())
+	{
+		return NIL;
+	}
+
+	CreatedbStmt *stmt = castNode(CreatedbStmt, node);
+	char *databaseName = stmt->dbname;
+	bool missingOk = false;
+	Oid databaseOid = get_database_oid(databaseName, missingOk);
+
+	/*
+	 * TODO: try to reuse regular DDL infrastructure
+	 *
+	 * We do not do this right now because of the AssignDatabaseToShard at the end.
+	 */
+	List *workerNodes = TargetWorkerSetNodeList(NON_COORDINATOR_METADATA_NODES, RowShareLock);
+	if (list_length(workerNodes) > 0)
+	{
+		char *createDatabaseCommand = DeparseTreeNode(node);
+
+		StringInfo internalCreateCommand = makeStringInfo();
+		appendStringInfo(internalCreateCommand,
+						 "SELECT pg_catalog.citus_internal_database_command(%s)",
+						 quote_literal_cstr(createDatabaseCommand));
+
+		/*
+		 * For the moment, we run CREATE DATABASE in 2PC, though that prevents
+		 * us from immediately doing a pg_dump | pg_restore when dealing with
+		 * a remote template database.
+		 */
+		bool outsideTransaction = false;
+
+		List *taskList = CreateDDLTaskList(internalCreateCommand->data, workerNodes,
+										   outsideTransaction);
+
+		bool localExecutionSupported = false;
+		ExecuteUtilityTaskList(taskList, localExecutionSupported);
+	}
+
+	/* synchronize pg_dist_object records */
+	ObjectAddress dbAddress = { 0 };
+	ObjectAddressSet(dbAddress, DatabaseRelationId, databaseOid);
+	MarkObjectDistributed(&dbAddress);
+
+
+	return NIL;
+}
+
+List *
+PreprocessDropDatabaseStmt(Node *node, const char *queryString,
+					 ProcessUtilityContext processUtilityContext)
+{
+	if (!EnableCreateDatabasePropagation || !ShouldPropagate())
+	{
+		return NIL;
+	}
+
+	DropdbStmt *stmt = (DropdbStmt *) node;
+	char *databaseName = stmt->dbname;
+	bool missingOk = true;
+	Oid databaseOid = get_database_oid(databaseName, missingOk);
+	if (databaseOid == InvalidOid)
+	{
+		/* let regular ProcessUtility deal with IF NOT EXISTS */
+		return NIL;
+	}
+
+	ObjectAddress dbAddress = { 0 };
+	ObjectAddressSet(dbAddress, DatabaseRelationId, databaseOid);
+	if (!IsObjectDistributed(&dbAddress))
+	{
+		return NIL;
+	}
+
+	List *workerNodes = TargetWorkerSetNodeList(NON_COORDINATOR_METADATA_NODES, RowShareLock);
+	if (list_length(workerNodes) == 0)
+	{
+		return NIL;
+	}
+
+	char *dropDatabaseCommand = DeparseTreeNode(node);
+
+	StringInfo internalDropCommand = makeStringInfo();
+	appendStringInfo(internalDropCommand,
+					 "SELECT pg_catalog.citus_internal_database_command(%s)",
+					 quote_literal_cstr(dropDatabaseCommand));
+
+
+	/* we execute here to avoid EnsureCoordinator check in ExecuteDistributedDDLJob */
+	bool outsideTransaction = false;
+	List *taskList = CreateDDLTaskList(internalDropCommand->data, workerNodes,
+									   outsideTransaction);
+
+	bool localExecutionSupported = false;
+	ExecuteUtilityTaskList(taskList, localExecutionSupported);
+
+	return NIL;
+}

src/backend/distributed/commands/distribute_object_ops.c

@@ -466,6 +466,28 @@ static DistributeObjectOps Database_Alter = {
 	.markDistributed = false,
 };
 
+static DistributeObjectOps Database_Create = {
+	.deparse = DeparseCreateDatabaseStmt,
+	.qualify = NULL,
+	.preprocess = NULL,
+	.postprocess = PostprocessCreateDatabaseStmt,
+	.objectType = OBJECT_DATABASE,
+	.operationType = DIST_OPS_CREATE,
+	.address = NULL,
+	.markDistributed = false,
+};
+
+static DistributeObjectOps Database_Drop = {
+	.deparse = DeparseDropDatabaseStmt,
+	.qualify = NULL,
+	.preprocess = PreprocessDropDatabaseStmt,
+	.postprocess = NULL,
+	.objectType = OBJECT_DATABASE,
+	.operationType = DIST_OPS_DROP,
+	.address = NULL,
+	.markDistributed = false,
+};
+
 #if PG_VERSION_NUM >= PG_VERSION_15
 static DistributeObjectOps Database_RefreshColl = {
 	.deparse = DeparseAlterDatabaseRefreshCollStmt,
@@ -1333,6 +1355,15 @@ GetDistributeObjectOps(Node *node)
 		{
 			return &Database_Alter;
 		}
+		case T_CreatedbStmt:
+		{
+			return &Database_Create;
+		}
+
+		case T_DropdbStmt:
+		{
+			return &Database_Drop;
+		}
 
 #if PG_VERSION_NUM >= PG_VERSION_15
 		case T_AlterDatabaseRefreshCollStmt:

src/backend/distributed/database/database_sharding.h

@@ -0,0 +1,53 @@
+/*
+ * database_sharding.h
+ *
+ * Data structure definition for managing backend data and related function
+ *
+ * Copyright (c) Microsoft, Inc.
+ */
+
+#ifndef DATABASE_SHARDING_H
+#define DATABASE_SHARDING_H
+
+
+#include "tcop/utility.h"
+
+
+/* attributes of citus_catalog.database_shard */
+#define Natts_database_shard 3
+#define Anum_database_shard_database_id 1
+#define Anum_database_shard_node_group_id 2
+#define Anum_database_shard_is_available 3
+
+
+typedef struct DatabaseShard
+{
+	/* database oid */
+	Oid databaseOid;
+
+	/* node group on which the database shard is placed */
+	int nodeGroupId;
+
+	/* whether the database shard is available */
+	bool isAvailable;
+} DatabaseShard;
+
+/* citus.enable_database_sharding setting */
+extern bool EnableDatabaseSharding;
+
+void PreProcessUtilityInDatabaseShard(Node *parseTree, const char *queryString,
+									  ProcessUtilityContext context,
+									  bool *runPreviousUtilityHook);
+void PostProcessUtilityInDatabaseShard(Node *parseTree, const char *queryString,
+									   ProcessUtilityContext context);
+bool DatabaseShardingEnabled(void);
+void AssignDatabaseToShard(Oid databaseOid);
+void UpdateDatabaseShard(Oid databaseOid, int targetNodeGroupId);
+void DeleteDatabaseShardByDatabaseIdLocally(Oid databaseOid);
+DatabaseShard * GetDatabaseShardByOid(Oid databaseOid);
+List * ListDatabaseShards(void);
+int64 CitusDatabaseSize(Oid databaseId);
+char * InsertDatabaseShardAssignmentCommand(Oid databaseOid, int nodeGroupId);
+
+
+#endif

src/backend/distributed/deparser/deparse_database_stmts.c

@@ -24,7 +24,7 @@
 #include "distributed/deparser.h"
 #include "distributed/log_utils.h"
 #include "parser/parse_type.h"
-
+#include "distributed/listutils.h"
 
 static void AppendAlterDatabaseOwnerStmt(StringInfo buf, AlterOwnerStmt *stmt);
 static void AppendAlterDatabaseStmt(StringInfo buf, AlterDatabaseStmt *stmt);
@@ -34,7 +34,7 @@ char *
 DeparseAlterDatabaseOwnerStmt(Node *node)
 {
 	AlterOwnerStmt *stmt = castNode(AlterOwnerStmt, node);
-	StringInfoData str = { 0 };
+	StringInfoData str = {0};
 	initStringInfo(&str);
 
 	Assert(stmt->objectType == OBJECT_DATABASE);
@@ -44,7 +44,6 @@ DeparseAlterDatabaseOwnerStmt(Node *node)
 	return str.data;
 }
 
-
 static void
 AppendAlterDatabaseOwnerStmt(StringInfo buf, AlterOwnerStmt *stmt)
 {
@@ -52,18 +51,17 @@ AppendAlterDatabaseOwnerStmt(StringInfo buf, AlterOwnerStmt *stmt)
 
 	appendStringInfo(buf,
 					 "ALTER DATABASE %s OWNER TO %s;",
-					 quote_identifier(strVal((String *) stmt->object)),
+					 quote_identifier(strVal((String *)stmt->object)),
 					 RoleSpecString(stmt->newowner, true));
 }
 
-
 static void
 AppendGrantDatabases(StringInfo buf, GrantStmt *stmt)
 {
 	ListCell *cell = NULL;
 	appendStringInfo(buf, " ON DATABASE ");
 
-	foreach(cell, stmt->objects)
+	foreach (cell, stmt->objects)
 	{
 		char *database = strVal(lfirst(cell));
 		appendStringInfoString(buf, quote_identifier(database));
@@ -74,7 +72,6 @@ AppendGrantDatabases(StringInfo buf, GrantStmt *stmt)
 	}
 }
 
-
 static void
 AppendGrantOnDatabaseStmt(StringInfo buf, GrantStmt *stmt)
 {
@@ -87,14 +84,12 @@ AppendGrantOnDatabaseStmt(StringInfo buf, GrantStmt *stmt)
 	AppendGrantSharedSuffix(buf, stmt);
 }
 
-
 static void
 AppendDefElemConnLimit(StringInfo buf, DefElem *def)
 {
-	appendStringInfo(buf, " CONNECTION LIMIT %ld", (long int) defGetNumeric(def));
+	appendStringInfo(buf, " CONNECTION LIMIT %ld", (long int)defGetNumeric(def));
 }
 
-
 static void
 AppendAlterDatabaseStmt(StringInfo buf, AlterDatabaseStmt *stmt)
 {
@@ -104,7 +99,7 @@ AppendAlterDatabaseStmt(StringInfo buf, AlterDatabaseStmt *stmt)
 	{
 		ListCell *cell = NULL;
 		appendStringInfo(buf, "WITH ");
-		foreach(cell, stmt->options)
+		foreach (cell, stmt->options)
 		{
 			DefElem *def = castNode(DefElem, lfirst(cell));
 			if (strcmp(def->defname, "is_template") == 0)
@@ -133,14 +128,13 @@ AppendAlterDatabaseStmt(StringInfo buf, AlterDatabaseStmt *stmt)
 	appendStringInfo(buf, ";");
 }
 
-
 char *
 DeparseGrantOnDatabaseStmt(Node *node)
 {
 	GrantStmt *stmt = castNode(GrantStmt, node);
 	Assert(stmt->objtype == OBJECT_DATABASE);
 
-	StringInfoData str = { 0 };
+	StringInfoData str = {0};
 	initStringInfo(&str);
 
 	AppendGrantOnDatabaseStmt(&str, stmt);
@@ -148,13 +142,12 @@ DeparseGrantOnDatabaseStmt(Node *node)
 	return str.data;
 }
 
-
 char *
 DeparseAlterDatabaseStmt(Node *node)
 {
 	AlterDatabaseStmt *stmt = castNode(AlterDatabaseStmt, node);
 
-	StringInfoData str = { 0 };
+	StringInfoData str = {0};
 	initStringInfo(&str);
 
 	AppendAlterDatabaseStmt(&str, stmt);
@@ -162,12 +155,11 @@ DeparseAlterDatabaseStmt(Node *node)
 	return str.data;
 }
 
-
 #if PG_VERSION_NUM >= PG_VERSION_15
 char *
 DeparseAlterDatabaseRefreshCollStmt(Node *node)
 {
-	AlterDatabaseRefreshCollStmt *stmt = (AlterDatabaseRefreshCollStmt *) node;
+	AlterDatabaseRefreshCollStmt *stmt = (AlterDatabaseRefreshCollStmt *)node;
 
 	StringInfoData str;
 	initStringInfo(&str);
@@ -179,7 +171,6 @@ DeparseAlterDatabaseRefreshCollStmt(Node *node)
 	return str.data;
 }
 
-
 #endif
 
 static void
@@ -192,16 +183,193 @@ AppendAlterDatabaseSetStmt(StringInfo buf, AlterDatabaseSetStmt *stmt)
 	AppendVariableSet(buf, varSetStmt);
 }
 
-
 char *
 DeparseAlterDatabaseSetStmt(Node *node)
 {
 	AlterDatabaseSetStmt *stmt = castNode(AlterDatabaseSetStmt, node);
 
-	StringInfoData str = { 0 };
+	StringInfoData str = {0};
 	initStringInfo(&str);
 
 	AppendAlterDatabaseSetStmt(&str, stmt);
 
 	return str.data;
 }
+
+char *
+DeparseCreateDatabaseSetStmt(Node *node)
+{
+	CreatedbStmt *stmt = castNode(CreatedbStmt, node);
+	StringInfoData str = {0};
+	initStringInfo(&str);
+
+	AppendCreatedbStmt(&str, stmt);
+
+	return str.data;
+}
+
+static void
+AppendCreatedbStmt(StringInfo buf, CreatedbStmt *stmt)
+{
+	appendStringInfo(buf,
+					 "CREATE DATABASE %s",
+					 quote_identifier(stmt->dbname));
+
+	DefElem *option = NULL;
+
+	foreach_ptr(option, stmt->options)
+	{
+		if (strcmp(option->defname, "tablespace") == 0)
+		{
+			char *tablespaceName = defGetString(option);
+
+			appendStringInfo(buf, " TABLESPACE %s",
+							 quote_identifier(tablespaceName));
+		}
+		else if (strcmp(option->defname, "owner") == 0)
+		{
+			char *owner = defGetString(option);
+
+			appendStringInfo(buf, " OWNER %s",
+							 quote_identifier(owner));
+		}
+		else if (strcmp(option->defname, "template") == 0)
+		{
+			char *template = defGetString(option);
+
+			appendStringInfo(buf, " TEMPLATE %s",
+							 quote_identifier(template));
+		}
+		else if (strcmp(option->defname, "encoding") == 0)
+		{
+			char *encoding = defGetString(option);
+
+			appendStringInfo(buf, " ENCODING %s",
+							 quote_literal_cstr(encoding));
+		}
+		else if (strcmp(option->defname, "locale") == 0)
+		{
+			char *locale = defGetString(option);
+
+			appendStringInfo(buf, " LOCALE %s",
+							 quote_literal_cstr(locale));
+		}
+		else if (strcmp(option->defname, "lc_collate") == 0)
+		{
+			char *lc_collate = defGetString(option);
+
+			appendStringInfo(buf, " LC_COLLATE %s",
+							 quote_literal_cstr(lc_collate));
+		}
+		else if (strcmp(option->defname, "lc_ctype") == 0)
+		{
+			char *lc_ctype = defGetString(option);
+
+			appendStringInfo(buf, " LC_CTYPE %s",
+							 quote_literal_cstr(lc_ctype));
+		}
+		else if (strcmp(option->defname, "icu_locale") == 0)
+		{
+			char *icuLocale = defGetString(option);
+
+			appendStringInfo(buf, " ICU_LOCALE %s",
+							 quote_literal_cstr(icuLocale));
+		}
+		else if (strcmp(option->defname, "locale_provider") == 0)
+		{
+			char *localeProvider = defGetString(option);
+
+			appendStringInfo(buf, " LOCALE_PROVIDER %s",
+							 quote_literal_cstr(localeProvider));
+		}
+		else if (strcmp(option->defname, "is_template") == 0)
+		{
+			bool isTemplate = defGetBoolean(option);
+
+			appendStringInfo(buf, " IS_TEMPLATE %s",
+							 isTemplate ? "true" : "false");
+		}
+		else if (strcmp(option->defname, "allow_connections") == 0)
+		{
+			bool allowConnections = defGetBoolean(option);
+
+			appendStringInfo(buf, " ALLOW_CONNECTIONS %s",
+							 allowConnections ? "true" : "false");
+		}
+		else if (strcmp(option->defname, "connection_limit") == 0)
+		{
+			int connectionLimit = defGetInt32(option);
+
+			appendStringInfo(buf, " CONNECTION_LIMIT %d", connectionLimit);
+		}
+#if PG_VERSION_NUM >= PG_VERSION_15
+		else if (strcmp(option->defname, "collation_version") == 0)
+		{
+			char *collationVersion = defGetString(option);
+
+			appendStringInfo(buf, " COLLATION_VERSION %s",
+							 quote_literal_cstr(collationVersion));
+		}
+		else if (strcmp(option->defname, "oid") == 0)
+		{
+			Oid objectId = defGetObjectId(option);
+
+			appendStringInfo(buf, " OID %d", objectId);
+		}
+		else if (strcmp(option->defname, "strategy") == 0)
+		{
+			char *strategy = defGetString(option);
+
+			appendStringInfo(buf, " STRATEGY %s",
+							 quote_literal_cstr(strategy));
+		}
+#endif
+		else if (strcmp(option->defname, "location") == 0)
+		{
+			/* deprecated option */
+		}
+		else
+		{
+			ereport(ERROR, (errcode(ERRCODE_SYNTAX_ERROR),
+							errmsg("unrecognized CREATE DATABASE option \"%s\"",
+								   option->defname)));
+		}
+	}
+}
+
+char *
+DeparseDropDatabaseStmt(Node *node)
+{
+	DropdbStmt *stmt = castNode(DropdbStmt, node);
+	StringInfoData str = { 0 };
+	initStringInfo(&str);
+
+	AppendDropDatabaseStmt(&str, stmt);
+
+	return str.data;
+}
+
+
+static void
+AppendDropDatabaseStmt(StringInfo buf, DropdbStmt *stmt)
+{
+	appendStringInfo(buf,
+					 "DROP DATABASE %s",
+					 quote_identifier(stmt->dbname));
+
+	DefElem *option = NULL;
+
+	foreach_ptr(option, stmt->options)
+	{
+		if (strcmp(option->defname, "force") == 0)
+		{
+			appendStringInfo(buf, " FORCE");
+		}
+		else
+		{
+			ereport(ERROR, (errcode(ERRCODE_SYNTAX_ERROR),
+							errmsg("unrecognized DROP DATABASE option \"%s\"",
+								   option->defname)));
+		}
+	}
+}

src/backend/distributed/sql/citus--12.1-1--12.2-1.sql

@@ -1,3 +1,14 @@
 -- citus--12.1-1--12.2-1
 
+/*
+ * citus_internal_database_command creates a database according to the given command.
+ */
+CREATE OR REPLACE FUNCTION pg_catalog.citus_internal_database_command(command text)
+ RETURNS void
+ LANGUAGE C
+ STRICT
+AS 'MODULE_PATHNAME', $$citus_internal_database_command$$;
+COMMENT ON FUNCTION pg_catalog.citus_internal_database_command(text) IS
+ 'run a database command without transaction block restrictions';
+
 -- bump version to 12.2-1

src/backend/distributed/sql/downgrades/citus--12.2-1--12.1-1.sql

@@ -1,2 +1,3 @@
 -- citus--12.2-1--12.1-1
+DROP FUNCTION pg_catalog.citus_internal_database_command(text);
 -- this is an empty downgrade path since citus--12.2-1--12.1-1.sql is empty for now

src/include/distributed/deparser.h

@@ -227,6 +227,9 @@ extern char * DeparseGrantOnDatabaseStmt(Node *node);
 extern char * DeparseAlterDatabaseStmt(Node *node);
 extern char * DeparseAlterDatabaseRefreshCollStmt(Node *node);
 extern char * DeparseAlterDatabaseSetStmt(Node *node);
+extern char * DeparseCreateDatabaseStmt(Node *node);
+extern char * DeparseDropDatabaseStmt(Node *node);
+
 
 
 /* forward declaration for deparse_publication_stmts.c */

src/include/distributed/metadata/distobject.h

@@ -21,6 +21,7 @@
 extern bool ObjectExists(const ObjectAddress *address);
 extern bool CitusExtensionObject(const ObjectAddress *objectAddress);
 extern bool IsAnyObjectDistributed(const List *addresses);
+extern bool IsObjectDistributed(const ObjectAddress *address);
 extern bool ClusterHasDistributedFunctionWithDistArgument(void);
 extern void MarkObjectDistributed(const ObjectAddress *distAddress);
 extern void MarkObjectDistributedViaSuperUser(const ObjectAddress *distAddress);