Fixes review items

src/backend/distributed/commands/common.c

@@ -14,8 +14,10 @@
 #include "postgres.h"
 
 #include "catalog/objectaddress.h"
+#include "catalog/pg_database.h"
 #include "catalog/pg_ts_config.h"
 #include "catalog/pg_ts_dict.h"
+#include "commands/dbcommands.h"
 #include "nodes/parsenodes.h"
 #include "tcop/utility.h"
 
@@ -28,8 +30,6 @@
 #include "distributed/metadata/distobject.h"
 #include "distributed/multi_executor.h"
 #include "distributed/worker_transaction.h"
-#include "catalog/pg_database.h"
-#include "commands/dbcommands.h"
 
 
 /*

src/backend/distributed/commands/database.c

@@ -10,46 +10,53 @@
  */
 
 #include "postgres.h"
+#include "miscadmin.h"
 
+#include "access/heapam.h"
 #include "access/htup_details.h"
 #include "access/xact.h"
 #include "catalog/objectaddress.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_database.h"
+#include "catalog/pg_database_d.h"
+#include "catalog/pg_tablespace.h"
 #include "commands/dbcommands.h"
-#include "miscadmin.h"
 #include "nodes/parsenodes.h"
-#include "utils/syscache.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/relcache.h"
+#include "utils/syscache.h"
 
+#include "distributed/adaptive_executor.h"
 #include "distributed/commands.h"
 #include "distributed/commands/utility_hook.h"
+#include "distributed/deparse_shard_query.h"
 #include "distributed/deparser.h"
+#include "distributed/listutils.h"
+#include "distributed/metadata/distobject.h"
 #include "distributed/metadata_sync.h"
 #include "distributed/metadata_utility.h"
 #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/worker_transaction.h"
-#include "distributed/deparse_shard_query.h"
-#include "distributed/listutils.h"
-#include "distributed/adaptive_executor.h"
-#include "access/htup_details.h"
-#include "catalog/pg_tablespace.h"
-#include "access/heapam.h"
-#include "utils/relcache.h"
-#include "utils/rel.h"
-#include "utils/lsyscache.h"
-#include "catalog/pg_collation.h"
-#include "utils/relcache.h"
-#include "catalog/pg_database_d.h"
 
 
+/*
+ * DatabaseCollationInfo is used to store collation related information of a database
+ */
+typedef struct DatabaseCollationInfo
+{
+	char *collation;
+	char *ctype;
+	#if PG_VERSION_NUM >= PG_VERSION_15
+	char *icu_locale;
+	char *collversion;
+	#endif
+} DatabaseCollationInfo;
+
 static AlterOwnerStmt * RecreateAlterDatabaseOwnerStmt(Oid databaseOid);
-
-
-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);
@@ -264,6 +271,13 @@ PreprocessAlterDatabaseSetStmt(Node *node, const char *queryString,
 }
 
 
+/*
+ * PostprocessAlterDatabaseStmt is executed before the statement is applied to the local
+ * postgres instance.
+ *
+ * In this stage, we can perform validations and prepare the commands that need to
+ * be run on all workers to grant.
+ */
 List *
 PreprocessCreateDatabaseStmt(Node *node, const char *queryString,
 							 ProcessUtilityContext processUtilityContext)
@@ -304,82 +318,21 @@ PostprocessCreateDatabaseStmt(Node *node, const char *queryString)
 								(void *) createDatabaseCommand,
 								ENABLE_DDL_PROPAGATION);
 
-	return NontransactionalNodeDDLTask(NON_COORDINATOR_NODES, commands);
+	return NontransactionalNodeDDLTaskList(NON_COORDINATOR_NODES, commands);
 }
 
 
 /*
- * citus_internal_database_command is an internal UDF to
+ * PostprocessAlterDatabaseStmt is executed after the statement is applied to the local
- * create/drop a database in an idempotent maner without
+ * postgres instance. In this stage we can prepare the commands that need to be run on
- * transaction block restrictions.
+ * all workers to drop the database. Since the DROP DATABASE statement gives error in
+ * transaction context, we need to use NontransactionalNodeDDLTaskList to send the
+ * DROP DATABASE statement to the workers.
  */
-Datum
-citus_internal_database_command(PG_FUNCTION_ARGS)
-{
-	int saveNestLevel = NewGUCNestLevel();
-	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);
-
-	/*
-	 * createdb() / DropDatabase() uses ParseState to report the error position for the
-	 * input command and the position is reported to be 0 when it's provided as NULL.
-	 * We're okay with that because we don't expect this UDF to be called with an incorrect
-	 * DDL command.
-	 *
-	 */
-	ParseState *pstate = NULL;
-
-	if (IsA(parseTree, CreatedbStmt))
-	{
-		CreatedbStmt *stmt = castNode(CreatedbStmt, parseTree);
-
-		bool missingOk = true;
-		Oid databaseOid = get_database_oid(stmt->dbname, missingOk);
-
-		if (!OidIsValid(databaseOid))
-		{
-			createdb(pstate, (CreatedbStmt *) parseTree);
-		}
-	}
-	else if (IsA(parseTree, DropdbStmt))
-	{
-		DropdbStmt *stmt = castNode(DropdbStmt, parseTree);
-
-		bool missingOk = false;
-		Oid databaseOid = get_database_oid(stmt->dbname, missingOk);
-
-
-		if (OidIsValid(databaseOid))
-		{
-			DropDatabase(pstate, (DropdbStmt *) parseTree);
-		}
-	}
-	else
-	{
-		ereport(ERROR, (errmsg("unsupported command type %d", nodeTag(parseTree))));
-	}
-
-	/* Below command rollbacks flags to the state before this session*/
-	AtEOXact_GUC(true, saveNestLevel);
-
-	PG_RETURN_VOID();
-}
-
-
 List *
 PreprocessDropDatabaseStmt(Node *node, const char *queryString,
 						   ProcessUtilityContext processUtilityContext)
 {
-	bool isPostProcess = false;
 	if (!EnableCreateDatabasePropagation || !ShouldPropagate())
 	{
 		return NIL;
@@ -389,41 +342,50 @@ PreprocessDropDatabaseStmt(Node *node, const char *queryString,
 
 	DropdbStmt *stmt = (DropdbStmt *) node;
 
+	bool isPostProcess = false;
 	List *addresses = GetObjectAddressListFromParseTree(node, stmt->missing_ok,
 														isPostProcess);
 
-	if (list_length(addresses) == 0)
+	if (list_length(addresses) != 1)
 	{
-		return NIL;
+		ereport(ERROR, (errmsg("unexpected number of objects found when "
+							   "executing DROP DATABASE command")));
 	}
 
 	ObjectAddress *address = (ObjectAddress *) linitial(addresses);
-	if (address->objectId == InvalidOid || !IsObjectDistributed(address))
+	if (address->objectId == InvalidOid || !IsAnyObjectDistributed(list_make1(address)))
 	{
 		return NIL;
 	}
 
 	char *dropDatabaseCommand = DeparseTreeNode(node);
 
-
 	List *commands = list_make3(DISABLE_DDL_PROPAGATION,
 								(void *) dropDatabaseCommand,
 								ENABLE_DDL_PROPAGATION);
 
-	return NontransactionalNodeDDLTask(NON_COORDINATOR_NODES, commands);
+	return NontransactionalNodeDDLTaskList(NON_COORDINATOR_NODES, commands);
 }
 
 
+/*
+ * GetDatabaseAddressFromDatabaseName gets the database name and returns the ObjectAddress
+ * of the database.
+ */
 static ObjectAddress *
 GetDatabaseAddressFromDatabaseName(char *databaseName, bool missingOk)
 {
 	Oid databaseOid = get_database_oid(databaseName, missingOk);
-	ObjectAddress *dbAddress = palloc0(sizeof(ObjectAddress));
+	ObjectAddress *dbObjectAddress = palloc0(sizeof(ObjectAddress));
-	ObjectAddressSet(*dbAddress, DatabaseRelationId, databaseOid);
+	ObjectAddressSet(*dbObjectAddress, DatabaseRelationId, databaseOid);
-	return dbAddress;
+	return dbObjectAddress;
 }
 
 
+/*
+ * DropDatabaseStmtObjectAddress gets the ObjectAddress of the database that is the
+ * object of the DropdbStmt.
+ */
 List *
 DropDatabaseStmtObjectAddress(Node *node, bool missing_ok, bool isPostprocess)
 {
@@ -434,6 +396,10 @@ DropDatabaseStmtObjectAddress(Node *node, bool missing_ok, bool isPostprocess)
 }
 
 
+/*
+ * CreateDatabaseStmtObjectAddress gets the ObjectAddress of the database that is the
+ * object of the CreatedbStmt.
+ */
 List *
 CreateDatabaseStmtObjectAddress(Node *node, bool missing_ok, bool isPostprocess)
 {
@@ -444,6 +410,9 @@ CreateDatabaseStmtObjectAddress(Node *node, bool missing_ok, bool isPostprocess)
 }
 
 
+/*
+ * GetTablespaceName gets the tablespace oid and returns the tablespace name.
+ */
 static char *
 GetTablespaceName(Oid tablespaceOid)
 {
@@ -462,19 +431,6 @@ GetTablespaceName(Oid tablespaceOid)
 }
 
 
-/*
- * DatabaseCollationInfo is used to store collation related information of a database
- */
-typedef struct DatabaseCollationInfo
-{
-	char *collation;
-	char *ctype;
-	#if PG_VERSION_NUM >= PG_VERSION_15
-	char *icu_locale;
-	char *collversion;
-	#endif
-} DatabaseCollationInfo;
-
 /*
  * GetDatabaseCollation gets oid of a database and returns all the collation related information
  * We need this method since collation related info in Form_pg_database is not accessible
@@ -548,6 +504,9 @@ GetDatabaseCollation(Oid db_oid)
 }
 
 
+/*
+ * FreeDatabaseCollationInfo frees the memory allocated for DatabaseCollationInfo
+ */
 static void
 FreeDatabaseCollationInfo(DatabaseCollationInfo collInfo)
 {
@@ -569,8 +528,13 @@ FreeDatabaseCollationInfo(DatabaseCollationInfo collInfo)
 
 
 #if PG_VERSION_NUM >= PG_VERSION_15
+
+/*
+ * GetLocaleProviderString gets the datlocprovider stored in pg_database
+ * and returns the string representation of the datlocprovider
+ */
 static char *
-get_locale_provider_string(char datlocprovider)
+GetLocaleProviderString(char datlocprovider)
 {
 	switch (datlocprovider)
 	{
@@ -599,7 +563,8 @@ get_locale_provider_string(char datlocprovider)
 
 
 /*
- * GenerateCreateDatabaseStatementFromPgDatabase is gets the pg_database tuple and returns the CREATE DATABASE statement
+ * GenerateCreateDatabaseStatementFromPgDatabase gets the pg_database tuple and returns the
+ * CREATE DATABASE statement that can be used to create given database.
  */
 static char *
 GenerateCreateDatabaseStatementFromPgDatabase(Form_pg_database databaseForm)
@@ -642,7 +607,7 @@ GenerateCreateDatabaseStatementFromPgDatabase(Form_pg_database databaseForm)
 
 	if (databaseForm->datlocprovider != 0)
 	{
-		appendStringInfo(&str, " LOCALE_PROVIDER = '%s'", get_locale_provider_string(
+		appendStringInfo(&str, " LOCALE_PROVIDER = '%s'", GetLocaleProviderString(
 							 databaseForm->datlocprovider));
 	}
 
@@ -678,19 +643,21 @@ GenerateCreateDatabaseStatementFromPgDatabase(Form_pg_database databaseForm)
 
 
 /*
- * GenerateCreateDatabaseCommandList is gets the pg_database tuples and returns the CREATE DATABASE statement list
+ * GenerateCreateDatabaseCommandList gets a list of pg_database tuples and returns
- * for all the databases in the cluster.citus_internal_database_command UDF is used to send the CREATE DATABASE
+ * a list of CREATE DATABASE statements for all the databases.
- * statement to the workers since the CREATE DATABASE statement gives error in transaction context.
+ *
+ * Commands in the list are wrapped by citus_internal_database_command() UDF
+ * to avoid from transaction block restrictions that apply to database commands
  */
 List *
 GenerateCreateDatabaseCommandList(void)
 {
 	List *commands = NIL;
-	HeapTuple tuple;
 
 	Relation pgDatabaseRel = table_open(DatabaseRelationId, AccessShareLock);
 	TableScanDesc scan = table_beginscan_catalog(pgDatabaseRel, 0, NULL);
 
+	HeapTuple tuple = NULL;
 	while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
 	{
 		Form_pg_database databaseForm = (Form_pg_database) GETSTRUCT(tuple);
@@ -702,7 +669,7 @@ GenerateCreateDatabaseCommandList(void)
 
 		/* Generate the CREATE DATABASE statement */
 		appendStringInfo(outerDbStmt,
-						 "select pg_catalog.citus_internal_database_command( %s)",
+						 "SELECT pg_catalog.citus_internal_database_command( %s)",
 						 quote_literal_cstr(
 							 createStmt));
 

src/backend/distributed/commands/role.c

@@ -65,6 +65,7 @@ static DefElem * makeDefElemBool(char *name, bool value);
 static List * GenerateRoleOptionsList(HeapTuple tuple);
 static List * GenerateGrantRoleStmtsFromOptions(RoleSpec *roleSpec, List *options);
 static List * GenerateGrantRoleStmtsOfRole(Oid roleid);
+static void EnsureSequentialModeForRoleDDL(void);
 
 static char * GetRoleNameFromDbRoleSetting(HeapTuple tuple,
 										   TupleDesc DbRoleSettingDescription);

src/backend/distributed/commands/utility_hook.c

@@ -25,7 +25,6 @@
  *-------------------------------------------------------------------------
  */
 
-#include "distributed/pg_version_constants.h"
 
 #include "postgres.h"
 #include "miscadmin.h"
@@ -35,6 +34,7 @@
 #include "access/htup_details.h"
 #include "catalog/catalog.h"
 #include "catalog/dependency.h"
+#include "catalog/pg_database.h"
 #include "citus_version.h"
 #include "commands/dbcommands.h"
 #include "commands/defrem.h"
@@ -62,6 +62,7 @@
 #include "distributed/multi_executor.h"
 #include "distributed/multi_explain.h"
 #include "distributed/multi_physical_planner.h"
+#include "distributed/pg_version_constants.h"
 #include "distributed/reference_table_utils.h"
 #include "distributed/resource_lock.h"
 #include "distributed/string_utils.h"
@@ -80,7 +81,6 @@
 #include "utils/inval.h"
 #include "utils/lsyscache.h"
 #include "utils/syscache.h"
-#include "catalog/pg_database.h"
 
 
 bool EnableDDLPropagation = true; /* ddl propagation is enabled */
@@ -579,7 +579,6 @@ citus_ProcessUtilityInternal(PlannedStmt *pstmt,
 		PreprocessLockStatement((LockStmt *) parsetree, context);
 	}
 
-
 	/*
 	 * We only process ALTER TABLE ... ATTACH PARTITION commands in the function below
 	 * and distribute the partition if necessary.
@@ -726,12 +725,13 @@ citus_ProcessUtilityInternal(PlannedStmt *pstmt,
 	}
 
 	/*
-	 * Make sure that dropping the role and database deletes the pg_dist_object entries. There is a
+	 * Make sure that dropping node-wide objects deletes the pg_dist_object
-	 * separate logic for roles and database, since roles and database are not included as dropped objects in the
+	 * entries. There is a separate logic for node-wide objects (such as role
-	 * drop event trigger. To handle it both on worker and coordinator nodes, it is not
+	 * and databases), since they are not included as dropped objects in the
-	 * implemented as a part of process functions but here.
+	 * drop event trigger. To handle it both on worker and coordinator nodes,
+	 * it is not implemented as a part of process functions but here.
 	 */
-	UnmarkRolesAndDatabaseDistributed(parsetree);
+	UnmarkNodeWideObjectsDistributed(parsetree);
 
 	pstmt->utilityStmt = parsetree;
 
@@ -1265,10 +1265,12 @@ ExecuteDistributedDDLJob(DDLJob *ddlJob)
 			{
 				ereport(WARNING,
 						(errmsg(
-							 "Commands that are not transaction-safe may result in partial failure"
+							 "Commands that are not transaction-safe may result in "
-							 ", potentially leading to an inconsistent state.\nIf the problematic command"
+							 "partial failure, potentially leading to an inconsistent "
-							 " is a CREATE operation, consider using the 'IF EXISTS' syntax to drop the "
+							 "state.\nIf the problematic command is a CREATE operation, "
-							 "object,\nif applicable, and then reattempt the original command.")));
+							 "consider using the 'IF EXISTS' syntax to drop the object,"
+							 "\nif applicable, and then re-attempt the original command.")));
+
 				PG_RE_THROW();
 			}
 		}
@@ -1483,12 +1485,12 @@ DDLTaskList(Oid relationId, const char *commandString)
 
 
 /*
- * NontransactionalNodeDDLTask builds a list of tasks to execute a DDL command on a
+ * NontransactionalNodeDDLTaskList builds a list of tasks to execute a DDL command on a
  * given target set of nodes with cannotBeExecutedInTransaction is set to make sure
- * that list is being executed without a transaction.
+ * that task list is executed outside a transaction block.
  */
 List *
-NontransactionalNodeDDLTask(TargetWorkerSet targets, List *commands)
+NontransactionalNodeDDLTaskList(TargetWorkerSet targets, List *commands)
 {
 	List *ddlJobs = NodeDDLTaskList(targets, commands);
 	DDLJob *ddlJob = NULL;

src/backend/distributed/deparser/citus_deparseutils.c

@@ -1,56 +1,66 @@
-
+/*
+ * citus_deparseutils.c
+ * ---------------------
+ *
+ * This file contains common functions used for deparsing PostgreSQL statements
+ * to their equivalent SQL representation.
+ *
+ */
 #include "postgres.h"
-#include "utils/builtins.h"
+
 #include "commands/defrem.h"
+#include "distributed/deparser.h"
+#include "distributed/pg_version_constants.h"
+#include "utils/builtins.h"
 #include "utils/elog.h"
 #include "utils/rel.h"
 #include "utils/relcache.h"
 #include "utils/syscache.h"
 #include "utils/typcache.h"
-#include "distributed/deparser.h"
-#include "distributed/pg_version_constants.h"
 
 
 /**
- * Convert a DefElem option to a SQL statement and append it to the given StringInfo buffer.
+ * DefElemOptionToStatement converts a DefElem option to a SQL statement and
+ * appends it to the given StringInfo buffer.
  *
  * @param buf The StringInfo buffer to append the SQL statement to.
  * @param option The DefElem option to convert to a SQL statement.
- * @param opt_formats The option format specification to use for the conversion.
+ * @param optionFormats The option format specification to use for the conversion.
- * @param num_opt_formats The number of option formats in the opt_formats array.
+ * @param optionFormatsLen The number of option formats in the opt_formats array.
  */
 void
-optionToStatement(StringInfo buf, DefElem *option, const struct
+DefElemOptionToStatement(StringInfo buf, DefElem *option, const
-				  option_format *opt_formats, int
+						 DefElemOptionFormat *optionFormats, int
-				  opt_formats_len)
+						 optionFormatsLen)
 {
 	const char *name = option->defname;
 	int i;
 
-	for (i = 0; i < opt_formats_len; i++)
+	for (i = 0; i < optionFormatsLen; i++)
 	{
-		if (strcmp(name, opt_formats[i].name) == 0)
+		if (strcmp(name, optionFormats[i].name) == 0)
 		{
-			switch (opt_formats[i].type)
+			switch (optionFormats[i].type)
 			{
 				case OPTION_FORMAT_STRING:
 				{
 					char *value = defGetString(option);
-					appendStringInfo(buf, opt_formats[i].format, quote_identifier(value));
+					appendStringInfo(buf, optionFormats[i].format, quote_identifier(
+										 value));
 					break;
 				}
 
 				case OPTION_FORMAT_INTEGER:
 				{
 					int32 value = defGetInt32(option);
-					appendStringInfo(buf, opt_formats[i].format, value);
+					appendStringInfo(buf, optionFormats[i].format, value);
 					break;
 				}
 
 				case OPTION_FORMAT_BOOLEAN:
 				{
 					bool value = defGetBoolean(option);
-					appendStringInfo(buf, opt_formats[i].format, value ? "true" :
+					appendStringInfo(buf, optionFormats[i].format, value ? "true" :
 									 "false");
 					break;
 				}
@@ -59,7 +69,7 @@ optionToStatement(StringInfo buf, DefElem *option, const struct
 				case OPTION_FORMAT_OBJECT_ID:
 				{
 					Oid value = defGetObjectId(option);
-					appendStringInfo(buf, opt_formats[i].format, value);
+					appendStringInfo(buf, optionFormats[i].format, value);
 					break;
 				}
 
@@ -67,14 +77,14 @@ optionToStatement(StringInfo buf, DefElem *option, const struct
 				case OPTION_FORMAT_LITERAL_CSTR:
 				{
 					char *value = defGetString(option);
-					appendStringInfo(buf, opt_formats[i].format, quote_literal_cstr(
+					appendStringInfo(buf, optionFormats[i].format, quote_literal_cstr(
 										 value));
 					break;
 				}
 
 				default:
 				{
-					elog(ERROR, "unrecognized option type: %d", opt_formats[i].type);
+					elog(ERROR, "unrecognized option type: %d", optionFormats[i].type);
 					break;
 				}
 			}

src/backend/distributed/deparser/deparse_database_stmts.c

@@ -12,25 +12,25 @@
 #include "postgres.h"
 
 #include "pg_version_compat.h"
-
 #include "catalog/namespace.h"
 #include "lib/stringinfo.h"
 #include "nodes/parsenodes.h"
 #include "utils/builtins.h"
 
-#include "distributed/deparser.h"
-#include "distributed/citus_ruleutils.h"
 #include "commands/defrem.h"
 #include "distributed/deparser.h"
+#include "distributed/citus_ruleutils.h"
+#include "distributed/deparser.h"
+#include "distributed/listutils.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);
 static void AppendDefElemConnLimit(StringInfo buf, DefElem *def);
 
-const struct option_format create_database_option_formats[] = {
+const DefElemOptionFormat create_database_option_formats[] = {
 	{ "owner", " OWNER %s", OPTION_FORMAT_STRING },
 	{ "template", " TEMPLATE %s", OPTION_FORMAT_STRING },
 	{ "encoding", " ENCODING %s", OPTION_FORMAT_LITERAL_CSTR },
@@ -49,6 +49,22 @@ const struct option_format create_database_option_formats[] = {
 	{ "oid", " OID %d", OPTION_FORMAT_OBJECT_ID }
 };
 
+/*
+ * DeparseAlterDatabaseOwnerStmt
+ *      Deparse an AlterDatabaseOwnerStmt node
+ *
+ * This function is responsible for producing a string representation of an
+ * AlterDatabaseOwnerStmt node, which represents an ALTER DATABASE statement
+ * that changes the owner of a database. The output string includes the ALTER
+ * DATABASE keyword, the name of the database being altered, and the new owner
+ * of the database.
+ *
+ * Parameters:
+ *  - node: a pointer to the AlterDatabaseOwnerStmt node to be deparsed
+ *
+ * Returns:
+ *  - a string representation of the ALTER DATABASE statement
+ */
 char *
 DeparseAlterDatabaseOwnerStmt(Node *node)
 {
@@ -64,6 +80,15 @@ DeparseAlterDatabaseOwnerStmt(Node *node)
 }
 
 
+/*
+ *
+ * AppendAlterDatabaseOwnerStmt
+ * Append an ALTER DATABASE statement for changing the owner of a database to the given StringInfo buffer.
+ *
+ * Parameters:
+ *  - buf: The StringInfo buffer to append the statement to.
+ *  - stmt: The AlterOwnerStmt representing the ALTER DATABASE statement to append.
+ */
 static void
 AppendAlterDatabaseOwnerStmt(StringInfo buf, AlterOwnerStmt *stmt)
 {
@@ -226,6 +251,32 @@ DeparseAlterDatabaseSetStmt(Node *node)
 }
 
 
+/*
+ *  Validates for if option is template, lc_type, locale or lc_collate, propagation will
+ * not be supported since template and strategy options are not stored in the catalog
+ * and lc_type, locale and lc_collate options depends on template parameter.
+ */
+static void
+ValidateCreateDatabaseOptions(DefElem *option)
+{
+	if (strcmp(option->defname, "template") == 0 ||
+		strcmp(option->defname, "strategy") == 0 ||
+		strcmp(option->defname, "lc_ctype") == 0 ||
+		strcmp(option->defname, "locale") == 0 ||
+		strcmp(option->defname, "lc_collate") == 0 ||
+		strcmp(option->defname, "icu_locale") == 0 ||
+		strcmp(option->defname, "locale_provider") == 0)
+	{
+		ereport(ERROR,
+				errmsg("CREATE DATABASE option \"%s\" is not supported",
+					   option->defname));
+	}
+}
+
+
+/*
+ * Prepares a CREATE DATABASE statement with given empty StringInfo buffer and CreatedbStmt node.
+ */
 static void
 AppendCreateDatabaseStmt(StringInfo buf, CreatedbStmt *stmt)
 {
@@ -237,27 +288,18 @@ AppendCreateDatabaseStmt(StringInfo buf, CreatedbStmt *stmt)
 
 	foreach_ptr(option, stmt->options)
 	{
-		/*If option is template, lc_type, locale or lc_collate, propagation will not be supportted */
+		ValidateCreateDatabaseOptions(option);
-		/* since template database is not stored in the catalog */
-		if (strcmp(option->defname, "template") == 0 ||
-			strcmp(option->defname, "strategy") == 0 ||
-			strcmp(option->defname, "lc_ctype") == 0 ||
-			strcmp(option->defname, "locale") == 0 ||
-			strcmp(option->defname, "lc_collate") == 0 ||
-			strcmp(option->defname, "icu_locale") == 0 ||
-			strcmp(option->defname, "locale_provider") == 0)
-		{
-			ereport(ERROR,
-					errmsg("CREATE DATABASE option \"%s\" is not supported",
-						   option->defname));
-		}
 
-		optionToStatement(buf, option, create_database_option_formats, lengthof(
+		DefElemOptionToStatement(buf, option, create_database_option_formats,
-							  create_database_option_formats));
+								 lengthof(create_database_option_formats));
 	}
 }
 
 
+/*
+ * Converts a CreatedbStmt structure into a SQL command string.
+ * Used in the deparsing of Create database statement.
+ */
 char *
 DeparseCreateDatabaseStmt(Node *node)
 {
@@ -271,13 +313,16 @@ DeparseCreateDatabaseStmt(Node *node)
 }
 
 
+/*
+ * Prepares a DROP  DATABASE statement with given empty StringInfo buffer and DropdbStmt node.
+ */
 static void
 AppendDropDatabaseStmt(StringInfo buf, DropdbStmt *stmt)
 {
-	char *if_exists_statement = stmt->missing_ok ? "IF EXISTS" : "";
+	char *ifExistsStatement = stmt->missing_ok ? "IF EXISTS" : "";
 	appendStringInfo(buf,
 					 "DROP DATABASE %s %s",
-					 if_exists_statement,
+					 ifExistsStatement,
 					 quote_identifier(stmt->dbname));
 
 	DefElem *option = NULL;
@@ -298,6 +343,10 @@ AppendDropDatabaseStmt(StringInfo buf, DropdbStmt *stmt)
 }
 
 
+/*
+ * Converts a DropdbStmt structure into a SQL command string.
+ * Used in the deparsing of drop database statement.
+ */
 char *
 DeparseDropDatabaseStmt(Node *node)
 {

src/backend/distributed/metadata/distobject.c

@@ -55,6 +55,7 @@
 static char * CreatePgDistObjectEntryCommand(const ObjectAddress *objectAddress);
 static int ExecuteCommandAsSuperuser(char *query, int paramCount, Oid *paramTypes,
 									 Datum *paramValues);
+static bool IsObjectDistributed(const ObjectAddress *address);
 
 PG_FUNCTION_INFO_V1(citus_unmark_object_distributed);
 PG_FUNCTION_INFO_V1(master_unmark_object_distributed);
@@ -358,8 +359,12 @@ ExecuteCommandAsSuperuser(char *query, int paramCount, Oid *paramTypes,
 }
 
 
+/*
+ * Deletes all pg_dist_object records for distributed roles in `DROP ROLE` statement a
+ * and for all databases in `DROP DATABASE` statement
+ */
 void
-UnmarkRolesAndDatabaseDistributed(Node *node)
+UnmarkNodeWideObjectsDistributed(Node *node)
 {
 	if (IsA(node, DropRoleStmt))
 	{
@@ -378,9 +383,9 @@ UnmarkRolesAndDatabaseDistributed(Node *node)
 		char *dbName = stmt->dbname;
 
 		Oid dbOid = get_database_oid(dbName, stmt->missing_ok);
-		ObjectAddress *dbAddress = palloc0(sizeof(ObjectAddress));
+		ObjectAddress *dbObjectAddress = palloc0(sizeof(ObjectAddress));
-		ObjectAddressSet(*dbAddress, DatabaseRelationId, dbOid);
+		ObjectAddressSet(*dbObjectAddress, DatabaseRelationId, dbOid);
-		UnmarkObjectDistributed(dbAddress);
+		UnmarkObjectDistributed(dbObjectAddress);
 	}
 }
 
@@ -420,7 +425,7 @@ UnmarkObjectDistributed(const ObjectAddress *address)
  * IsObjectDistributed returns if the object addressed is already distributed in the
  * cluster. This performs a local indexed lookup in pg_dist_object.
  */
-bool
+static bool
 IsObjectDistributed(const ObjectAddress *address)
 {
 	ScanKeyData key[3];

src/backend/distributed/metadata/metadata_sync.c

@@ -30,12 +30,15 @@
 #include "catalog/pg_attrdef.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_constraint.h"
+#include "catalog/pg_database.h"
+#include "catalog/pg_database_d.h"
 #include "catalog/pg_depend.h"
 #include "catalog/pg_foreign_server.h"
 #include "catalog/pg_namespace.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_type.h"
 #include "commands/async.h"
+#include "commands/dbcommands.h"
 #include "distributed/argutils.h"
 #include "distributed/backend_data.h"
 #include "distributed/citus_ruleutils.h"
@@ -179,6 +182,7 @@ PG_FUNCTION_INFO_V1(citus_internal_delete_colocation_metadata);
 PG_FUNCTION_INFO_V1(citus_internal_add_tenant_schema);
 PG_FUNCTION_INFO_V1(citus_internal_delete_tenant_schema);
 PG_FUNCTION_INFO_V1(citus_internal_update_none_dist_table_metadata);
+PG_FUNCTION_INFO_V1(citus_internal_database_command);
 
 
 static bool got_SIGTERM = false;
@@ -3895,6 +3899,80 @@ citus_internal_update_none_dist_table_metadata(PG_FUNCTION_ARGS)
 }
 
 
+/*
+ * 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)
+{
+	CheckCitusVersion(ERROR);
+	if (!ShouldSkipMetadataChecks())
+	{
+		EnsureCoordinatorInitiatedOperation();
+	}
+	PG_ENSURE_ARGNOTNULL(0, "database command");
+
+	text *commandText = PG_GETARG_TEXT_P(0);
+	char *command = text_to_cstring(commandText);
+	Node *parseTree = ParseTreeNode(command);
+
+	int saveNestLevel = NewGUCNestLevel();
+
+	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);
+
+	/*
+	 * createdb() / DropDatabase() uses ParseState to report the error position for the
+	 * input command and the position is reported to be 0 when it's provided as NULL.
+	 * We're okay with that because we don't expect this UDF to be called with an incorrect
+	 * DDL command.
+	 */
+	ParseState *pstate = NULL;
+
+	if (IsA(parseTree, CreatedbStmt))
+	{
+		CreatedbStmt *stmt = castNode(CreatedbStmt, parseTree);
+
+		bool missingOk = true;
+		Oid databaseOid = get_database_oid(stmt->dbname, missingOk);
+
+		if (!OidIsValid(databaseOid))
+		{
+			createdb(pstate, (CreatedbStmt *) parseTree);
+		}
+	}
+	else if (IsA(parseTree, DropdbStmt))
+	{
+		DropdbStmt *stmt = castNode(DropdbStmt, parseTree);
+
+		bool missingOk = false;
+		Oid databaseOid = get_database_oid(stmt->dbname, missingOk);
+
+
+		if (OidIsValid(databaseOid))
+		{
+			DropDatabase(pstate, (DropdbStmt *) parseTree);
+		}
+	}
+	else
+	{
+		ereport(ERROR, (errmsg("unsupported command type %d", nodeTag(parseTree))));
+	}
+
+	/* Rollbacks GUCs to the state before this session */
+	AtEOXact_GUC(true, saveNestLevel);
+
+	PG_RETURN_VOID();
+}
+
+
 /*
  * SyncNewColocationGroup synchronizes a new pg_dist_colocation entry to a worker.
  */
@@ -4503,7 +4581,7 @@ PropagateNodeWideObjectsCommandList(void)
 
 	if (EnableCreateDatabasePropagation)
 	{
-		/* Get commands for database creation */
+		/* get commands for database creation */
 		List *createDatabaseCommands = GenerateCreateDatabaseCommandList();
 		ddlCommands = list_concat(ddlCommands, createDatabaseCommands);
 	}

src/backend/distributed/shared_library_init.c

@@ -1266,7 +1266,7 @@ RegisterCitusConfigVariables(void)
 	DefineCustomBoolVariable(
 		"citus.enable_create_database_propagation",
 		gettext_noop("Enables propagating CREATE DATABASE "
-					 "and DROP DATABASE statements to workers"),
+					 "and DROP DATABASE statements to workers."),
 		NULL,
 		&EnableCreateDatabasePropagation,
 		false,

src/backend/distributed/sql/udfs/citus_internal_database_command/12.2-1.sql

@@ -4,7 +4,7 @@
 CREATE OR REPLACE FUNCTION pg_catalog.citus_internal_database_command(command text)
  RETURNS void
  LANGUAGE C
- STRICT
+ VOLATILE
 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';

src/backend/distributed/sql/udfs/citus_internal_database_command/latest.sql

@@ -4,7 +4,7 @@
 CREATE OR REPLACE FUNCTION pg_catalog.citus_internal_database_command(command text)
  RETURNS void
  LANGUAGE C
- STRICT
+ VOLATILE
 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';

src/include/distributed/commands.h

@@ -230,9 +230,6 @@ extern List * PreprocessAlterDatabaseRefreshCollStmt(Node *node, const char *que
 													 ProcessUtilityContext
 													 processUtilityContext);
 
-extern List * CreateDatabaseStmtObjectAddress(Node *node, bool missing_ok, bool
-											  isPostprocess);
-
 
 extern List * PreprocessAlterDatabaseSetStmt(Node *node, const char *queryString,
 											 ProcessUtilityContext processUtilityContext);
@@ -242,10 +239,10 @@ extern List * PreprocessCreateDatabaseStmt(Node *node, const char *queryString,
 extern List * PostprocessCreateDatabaseStmt(Node *node, const char *queryString);
 extern List * PreprocessDropDatabaseStmt(Node *node, const char *queryString,
 										 ProcessUtilityContext processUtilityContext);
-extern List * DropDatabaseStmtObjectAddress(Node *node, bool missing_ok, bool
+extern List * DropDatabaseStmtObjectAddress(Node *node, bool missing_ok,
-											isPostprocess);
+											bool isPostprocess);
-extern List * CreateDatabaseStmtObjectAddress(Node *node, bool missing_ok, bool
+extern List * CreateDatabaseStmtObjectAddress(Node *node, bool missing_ok,
-											  isPostprocess);
+											  bool isPostprocess);
 extern List * GenerateCreateDatabaseCommandList(void);
 
 
@@ -518,7 +515,6 @@ extern List * RenameRoleStmtObjectAddress(Node *stmt, bool missing_ok, bool
 
 extern void UnmarkRolesDistributed(List *roles);
 extern List * FilterDistributedRoles(List *roles);
-extern void EnsureSequentialModeForRoleDDL(void);
 
 /* schema.c - forward declarations */
 extern List * PostprocessCreateSchemaStmt(Node *node, const char *queryString);

src/include/distributed/commands/utility_hook.h

@@ -94,7 +94,7 @@ extern void ProcessUtilityParseTree(Node *node, const char *queryString,
 extern void MarkInvalidateForeignKeyGraph(void);
 extern void InvalidateForeignKeyGraphForDDL(void);
 extern List * DDLTaskList(Oid relationId, const char *commandString);
-extern List * NontransactionalNodeDDLTask(TargetWorkerSet targets, List *commands);
+extern List * NontransactionalNodeDDLTaskList(TargetWorkerSet targets, List *commands);
 extern List * NodeDDLTaskList(TargetWorkerSet targets, List *commands);
 extern bool AlterTableInProgress(void);
 extern bool DropSchemaOrDBInProgress(void);

src/include/distributed/deparser.h

@@ -123,12 +123,12 @@ extern void AppendGrantSharedSuffix(StringInfo buf, GrantStmt *stmt);
 
 /* Common deparser utils */
 
-struct option_format
+typedef struct DefElemOptionFormat
 {
-	const char *name;
+	char *name;
-	const char *format;
+	char *format;
-	const int type;
+	int type;
-};
+} DefElemOptionFormat;
 
 typedef enum OptionFormatType
 {
@@ -140,9 +140,9 @@ typedef enum OptionFormatType
 } OptionFormatType;
 
 
-extern void optionToStatement(StringInfo buf, DefElem *option, const struct
+extern void DefElemOptionToStatement(StringInfo buf, DefElem *option, const
-							  option_format *opt_formats, int
+									 DefElemOptionFormat *opt_formats, int
-							  opt_formats_len);
+									 opt_formats_len);
 
 
 /* forward declarations for deparse_statistics_stmts.c */

src/include/distributed/metadata/distobject.h

@@ -21,13 +21,12 @@
 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);
 extern void MarkObjectDistributedLocally(const ObjectAddress *distAddress);
 extern void UnmarkObjectDistributed(const ObjectAddress *address);
-extern void UnmarkRolesAndDatabaseDistributed(Node *node);
+extern void UnmarkNodeWideObjectsDistributed(Node *node);
 extern bool IsTableOwnedByExtension(Oid relationId);
 extern bool ObjectAddressDependsOnExtension(const ObjectAddress *target);
 extern bool IsAnyObjectAddressOwnedByExtension(const List *targets,

src/test/regress/citus_tests/run_test.py

@@ -151,8 +151,6 @@ DEPS = {
         ],
         worker_count=6,
     ),
-    "create_drop_database_propagation": TestDeps("minimal_schedule"),
-    "create_drop_database_propagation_pg15": TestDeps("minimal_schedule"),
     "function_propagation": TestDeps("minimal_schedule"),
     "citus_shards": TestDeps("minimal_schedule"),
     "grant_on_foreign_server_propagation": TestDeps("minimal_schedule"),