MDEV-35854: Clarify row_rename_table_for_mysql()

enum rename_fk: Replaces the "bool use_fk" parameter of
row_rename_table_for_mysql() and innobase_rename_table():

RENAME_IGNORE_FK: Replaces use_fk=false when the operation cannot
involve any FOREIGN KEY constraints, that is, it is a partitioned
table or an internal table for FULLTEXT INDEX.

RENAME_REBUILD: Replaces use_fk=false when the table may contain
FOREIGN KEY constraints, which must not be modified in the data
dictionary tables SYS_FOREIGN and SYS_FOREIGN_COLS.

RENAME_ALTER_COPY: Replaces use_fk=true. This is only specified
in ha_innobase::rename_table(), which may be invoked as part of
ALTER TABLE…ALGORITHM=COPY, but also during RENAME TABLE.

An alternative value RENAME_FK could be useful to specify in
ha_innobase::rename_table() when it is executed as part of
CREATE OR REPLACE TABLE, which currently is not an atomic operation.

Reviewed by: Debarun Banerjee

storage/innobase/fts/fts0fts.cc

@@ -1392,7 +1392,7 @@ static dberr_t fts_drop_table(trx_t *trx, const char *table_name, bool rename)
       char *tmp= dict_mem_create_temporary_tablename(heap, table->name.m_name,
                                                      table->id);
       dberr_t err= row_rename_table_for_mysql(table->name.m_name, tmp, trx,
-                                              false);
+                                              RENAME_IGNORE_FK);
       mem_heap_free(heap);
       if (err != DB_SUCCESS)
       {
@@ -1450,7 +1450,7 @@ fts_rename_one_aux_table(
 	fts_table_new_name[table_new_name_len] = 0;
 
 	return row_rename_table_for_mysql(
-		fts_table_old_name, fts_table_new_name, trx, false);
+		fts_table_old_name, fts_table_new_name, trx, RENAME_IGNORE_FK);
 }
 
 /****************************************************************//**

storage/innobase/handler/ha_innodb.cc

@@ -13889,10 +13889,10 @@ int ha_innobase::delete_table(const char *name)
 @param[in,out]	trx	InnoDB data dictionary transaction
 @param[in]	from	old table name
 @param[in]	to	new table name
-@param[in]	use_fk	whether to enforce FOREIGN KEY
+@param[in]	fk	how to handle FOREIGN KEY
 @return DB_SUCCESS or error code */
 static dberr_t innobase_rename_table(trx_t *trx, const char *from,
-                                     const char *to, bool use_fk)
+                                     const char *to, rename_fk fk)
 {
 	dberr_t	error;
 	char	norm_to[FN_REFLEN];
@@ -13910,7 +13910,7 @@ static dberr_t innobase_rename_table(trx_t *trx, const char *from,
 
 	ut_ad(trx->will_lock);
 
-	error = row_rename_table_for_mysql(norm_from, norm_to, trx, use_fk);
+	error = row_rename_table_for_mysql(norm_from, norm_to, trx, fk);
 
 	if (error != DB_SUCCESS) {
 		if (error == DB_TABLE_NOT_FOUND
@@ -13936,7 +13936,8 @@ static dberr_t innobase_rename_table(trx_t *trx, const char *from,
 #endif /* _WIN32 */
 				trx_start_if_not_started(trx, true);
 				error = row_rename_table_for_mysql(
-					par_case_name, norm_to, trx, false);
+					par_case_name, norm_to, trx,
+					RENAME_IGNORE_FK);
 			}
 		}
 
@@ -14132,7 +14133,8 @@ int ha_innobase::truncate()
 
   if (error == DB_SUCCESS)
   {
-    error= innobase_rename_table(trx, ib_table->name.m_name, temp_name, false);
+    error= innobase_rename_table(trx, ib_table->name.m_name, temp_name,
+                                 RENAME_REBUILD);
     if (error == DB_SUCCESS)
       error= trx->drop_table(*ib_table);
   }
@@ -14330,7 +14332,8 @@ ha_innobase::rename_table(
 	row_mysql_lock_data_dictionary(trx);
 
 	if (error == DB_SUCCESS) {
-		error = innobase_rename_table(trx, from, to, true);
+		error = innobase_rename_table(trx, from, to,
+					      RENAME_ALTER_COPY);
 	}
 
 	DEBUG_SYNC(thd, "after_innobase_rename_table");

storage/innobase/handler/handler0alter.cc

@@ -10414,10 +10414,12 @@ commit_try_rebuild(
 	char* old_name= mem_heap_strdup(ctx->heap, user_table->name.m_name);
 
 	dberr_t error = row_rename_table_for_mysql(user_table->name.m_name,
-						   ctx->tmp_name, trx, false);
+						   ctx->tmp_name, trx,
+						   RENAME_REBUILD);
 	if (error == DB_SUCCESS) {
 		error = row_rename_table_for_mysql(
-			rebuilt_table->name.m_name, old_name, trx, false);
+			rebuilt_table->name.m_name, old_name, trx,
+			RENAME_REBUILD);
 		if (error == DB_SUCCESS) {
 			/* The statistics for the surviving indexes will be
 			re-inserted in alter_stats_rebuild(). */

storage/innobase/include/row0mysql.h

@@ -370,6 +370,15 @@ row_import_tablespace_for_mysql(
 	row_prebuilt_t*	prebuilt)	/*!< in: prebuilt struct in MySQL */
         MY_ATTRIBUTE((nonnull, warn_unused_result));
 
+enum rename_fk {
+  /** ignore FOREIGN KEY constraints */
+  RENAME_IGNORE_FK= 0,
+  /** Rename a table as part of a native table-rebuilding DDL operation */
+  RENAME_REBUILD,
+  /** Rename as part of ALTER TABLE...ALGORITHM=COPY */
+  RENAME_ALTER_COPY
+};
+
 /*********************************************************************//**
 Renames a table for MySQL.
 @return error code or DB_SUCCESS */
@@ -379,7 +388,7 @@ row_rename_table_for_mysql(
 	const char*	old_name,	/*!< in: old table name */
 	const char*	new_name,	/*!< in: new table name */
 	trx_t*		trx,		/*!< in/out: transaction */
-	bool		use_fk)		/*!< in: whether to parse and enforce
+	rename_fk	fk)		/*!< in: how to handle
 					FOREIGN KEY constraints */
 	MY_ATTRIBUTE((nonnull, warn_unused_result));
 

storage/innobase/row/row0mysql.cc

@@ -2554,7 +2554,7 @@ row_rename_table_for_mysql(
 	const char*	old_name,	/*!< in: old table name */
 	const char*	new_name,	/*!< in: new table name */
 	trx_t*		trx,		/*!< in/out: transaction */
-	bool		use_fk)		/*!< in: whether to parse and enforce
+	rename_fk	fk)		/*!< in: how to handle
 					FOREIGN KEY constraints */
 {
 	dict_table_t*	table			= NULL;
@@ -2579,6 +2579,8 @@ row_rename_table_for_mysql(
 	old_is_tmp = dict_table_t::is_temporary_name(old_name);
 	new_is_tmp = dict_table_t::is_temporary_name(new_name);
 
+	ut_ad(fk != RENAME_IGNORE_FK || !new_is_tmp);
+
 	table = dict_table_open_on_name(old_name, true,
 					DICT_ERR_IGNORE_FK_NOKEY);
 
@@ -2638,10 +2640,9 @@ row_rename_table_for_mysql(
 			<< TROUBLESHOOTING_MSG;
 
 		goto funct_exit;
-
-	} else if (use_fk && !old_is_tmp && new_is_tmp) {
-		/* MySQL is doing an ALTER TABLE command and it renames the
-		original table to a temporary table name. We want to preserve
+	} else if (fk == RENAME_ALTER_COPY && !old_is_tmp && new_is_tmp) {
+		/* Non-native ALTER TABLE is renaming the
+		original table to a temporary name. We want to preserve
 		the original foreign key constraint definitions despite the
 		name change. An exception is those constraints for which
 		the ALTER TABLE contained DROP FOREIGN KEY <foreign key id>.*/
@@ -2685,7 +2686,7 @@ row_rename_table_for_mysql(
 		goto rollback_and_exit;
 	}
 
-	if (!new_is_tmp) {
+	if (/* fk == RENAME_IGNORE_FK || */ !new_is_tmp) {
 		/* Rename all constraints. */
 		char	new_table_name[MAX_TABLE_NAME_LEN + 1];
 		char	old_table_utf8[MAX_TABLE_NAME_LEN + 1];
@@ -2859,7 +2860,7 @@ row_rename_table_for_mysql(
 		err = dict_load_foreigns(
 			new_name, nullptr, trx->id,
 			!old_is_tmp || trx->check_foreigns,
-			use_fk
+			fk == RENAME_ALTER_COPY
 			? DICT_ERR_IGNORE_NONE
 			: DICT_ERR_IGNORE_FK_NOKEY,
 			fk_tables);