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 @@ err_exit:
 @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 (fk == RENAME_ALTER_COPY && !old_is_tmp && new_is_tmp) {
-	} else if (use_fk && !old_is_tmp && new_is_tmp) {
+		/* Non-native ALTER TABLE is renaming the
-		/* MySQL is doing an ALTER TABLE command and it renames the
+		original table to a temporary name. We want to preserve
-		original table to a temporary table 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);