MDEV-17938 ALTER TABLE reports ER_TABLESPACE_EXISTS after failed ALTER TABLE

There was a race condition in the error handling of ALTER TABLE when
the table contains FULLTEXT INDEX.

During the error handling of an erroneous ALTER TABLE statement,
when InnoDB would drop the internally created tables for FULLTEXT INDEX,
it could happen that one of the hidden tables was being concurrently
accessed by a background thread. Because of this, InnoDB would defer
the drop operation to the background.

However, related to MDEV-13564 backup-safe TRUNCATE TABLE and its
prerequisite MDEV-14585, we had to make the background drop table queue
crash-safe by renaming the table to a temporary name before enqueueing it.
This renaming was introduced in a follow-up of the MDEV-13407 fix.
As part of this rename operation, we were unnecessarily parsing the
current SQL statement, because the same rename operation could also be
executed as part of ALTER TABLE via ha_innobase::rename_table().

If an ALTER TABLE statement was being refused due to incorrectly formed
FOREIGN KEY constraint, then it could happen that the renaming of the hidden
internal tables for FULLTEXT INDEX could also fail, triggering a host of
error log messages, and causing a subsequent table-rebuilding ALTER TABLE
operation to fail due to the tablespace already existing.

innobase_rename_table(), row_rename_table_for_mysql(): Add the parameter
use_fk for suppressing the parsing of FOREIGN KEY constraints. It
will only be passed as use_fk=true by ha_innobase::rename_table(),
which can be invoked as part of ALTER TABLE...ALGORITHM=COPY.

storage/innobase/fts/fts0fts.cc

@@ -1511,8 +1511,8 @@ fts_rename_one_aux_table(
 	       table_new_name_len - new_db_name_len);
 	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));
+	return row_rename_table_for_mysql(
+		fts_table_old_name, fts_table_new_name, trx, false, false);
 }
 
 /****************************************************************//**
@@ -6256,7 +6256,7 @@ fts_rename_one_aux_table_to_hex_format(
 	}
 
 	error = row_rename_table_for_mysql(aux_table->name, new_name, trx,
-					   FALSE);
+					   false, false);
 
 	if (error != DB_SUCCESS) {
 		ib::warn() << "Failed to rename aux table '"
@@ -6395,7 +6395,7 @@ fts_rename_aux_tables_to_hex_format_low(
 			DICT_TF2_FLAG_UNSET(table, DICT_TF2_FTS_AUX_HEX_NAME);
 			err = row_rename_table_for_mysql(table->name.m_name,
 							 aux_table->name,
-							 trx_bg, FALSE);
+							 trx_bg, false, false);
 
 			trx_bg->dict_operation_lock_mode = 0;
 			dict_table_close(table, TRUE, FALSE);

storage/innobase/handler/ha_innodb.cc

@@ -13315,6 +13315,7 @@ innobase_drop_database(
 @param[in]	from	old table name
 @param[in]	to	new table name
 @param[in]	commit	whether to commit trx
+@param[in]	use_fk	whether to parse and enforce FOREIGN KEY constraints
 @return DB_SUCCESS or error code */
 inline
 dberr_t
@@ -13322,7 +13323,8 @@ innobase_rename_table(
 	trx_t*		trx,
 	const char*	from,
 	const char*	to,
-	bool		commit = true)
+	bool		commit,
+	bool		use_fk)
 {
 	dberr_t	error;
 	char	norm_to[FN_REFLEN];
@@ -13382,7 +13384,8 @@ innobase_rename_table(
 
 	ut_a(trx->will_lock > 0);
 
-	error = row_rename_table_for_mysql(norm_from, norm_to, trx, commit);
+	error = row_rename_table_for_mysql(norm_from, norm_to, trx, commit,
+					   use_fk);
 
 	if (error != DB_SUCCESS) {
 		if (error == DB_TABLE_NOT_FOUND
@@ -13407,7 +13410,8 @@ innobase_rename_table(
 #endif /* _WIN32 */
 				trx_start_if_not_started(trx, true);
 				error = row_rename_table_for_mysql(
-					par_case_name, norm_to, trx, TRUE);
+					par_case_name, norm_to, trx,
+					true, false);
 			}
 		}
 
@@ -13519,7 +13523,8 @@ int ha_innobase::truncate()
 	trx_set_dict_operation(trx, TRX_DICT_OP_TABLE);
 	row_mysql_lock_data_dictionary(trx);
 	int err = convert_error_code_to_mysql(
-		innobase_rename_table(trx, ib_table->name.m_name, temp_name, false),
+		innobase_rename_table(trx, ib_table->name.m_name, temp_name,
+				      false, false),
 		ib_table->flags, m_user_thd);
 	if (err) {
 		trx_rollback_for_mysql(trx);
@@ -13572,7 +13577,7 @@ ha_innobase::rename_table(
 	++trx->will_lock;
 	trx_set_dict_operation(trx, TRX_DICT_OP_INDEX);
 
-	dberr_t	error = innobase_rename_table(trx, from, to);
+	dberr_t	error = innobase_rename_table(trx, from, to, true, true);
 
 	DEBUG_SYNC(thd, "after_innobase_rename_table");
 

storage/innobase/include/row0mysql.h

@@ -470,7 +470,9 @@ 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		commit)		/*!< in: whether to commit trx */
+	bool		commit,		/*!< in: whether to commit trx */
+	bool		use_fk)		/*!< in: whether to parse and enforce
+					FOREIGN KEY constraints */
 	MY_ATTRIBUTE((nonnull, warn_unused_result));
 
 /*********************************************************************//**

storage/innobase/row/row0mysql.cc

@@ -3483,7 +3483,8 @@ row_drop_table_for_mysql(
 			ib::info() << "Deferring DROP TABLE " << table->name
 				   << "; renaming to " << tmp_name;
 			err = row_rename_table_for_mysql(
-				table->name.m_name, tmp_name, trx, false);
+				table->name.m_name, tmp_name, trx,
+				false, false);
 		} else {
 			err = DB_SUCCESS;
 		}
@@ -4127,7 +4128,9 @@ 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		commit)		/*!< in: whether to commit trx */
+	bool		commit,		/*!< in: whether to commit trx */
+	bool		use_fk)		/*!< in: whether to parse and enforce
+					FOREIGN KEY constraints */
 {
 	dict_table_t*	table			= NULL;
 	ibool		dict_locked		= FALSE;
@@ -4232,7 +4235,7 @@ row_rename_table_for_mysql(
 
 		goto funct_exit;
 
-	} else if (!old_is_tmp && new_is_tmp) {
+	} 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
 		the original foreign key constraint definitions despite the