Index: mysql-test/innodb_bug21704.result
===================================================================
--- mysql-test/innodb_bug21704.result	(revision 0)
+++ mysql-test/innodb_bug21704.result	(revision 5488)
@@ -0,0 +1,55 @@
+#
+# Bug#21704: Renaming column does not update FK definition.
+#
+
+# Test that it's not possible to rename columns participating in a
+# foreign key (either in the referencing or referenced table).
+
+DROP TABLE IF EXISTS t1;
+DROP TABLE IF EXISTS t2;
+DROP TABLE IF EXISTS t3;
+CREATE TABLE t1 (a INT PRIMARY KEY, b INT) ROW_FORMAT=COMPACT ENGINE=INNODB;
+CREATE TABLE t2 (a INT PRIMARY KEY, b INT,
+CONSTRAINT fk1 FOREIGN KEY (a) REFERENCES t1(a))
+ROW_FORMAT=COMPACT ENGINE=INNODB;
+CREATE TABLE t3 (a INT PRIMARY KEY, b INT, KEY(b), C INT,
+CONSTRAINT fk2 FOREIGN KEY (b) REFERENCES t3 (a))
+ROW_FORMAT=COMPACT ENGINE=INNODB;
+INSERT INTO t1 VALUES (1,1),(2,2),(3,3);
+INSERT INTO t2 VALUES (1,1),(2,2),(3,3);
+INSERT INTO t3 VALUES (1,1,1),(2,2,2),(3,3,3);
+
+# Test renaming the column in the referenced table.
+
+ALTER TABLE t1 CHANGE a c INT;
+ERROR HY000: Error on rename of '#sql-temporary' to './test/t1' (errno: 150)
+# Ensure that online column rename works.
+ALTER TABLE t1 CHANGE b c INT;
+affected rows: 0
+info: Records: 0  Duplicates: 0  Warnings: 0
+
+# Test renaming the column in the referencing table
+
+ALTER TABLE t2 CHANGE a c INT;
+ERROR HY000: Error on rename of '#sql-temporary' to './test/t2' (errno: 150)
+# Ensure that online column rename works.
+ALTER TABLE t2 CHANGE b c INT;
+affected rows: 0
+info: Records: 0  Duplicates: 0  Warnings: 0
+
+# Test with self-referential constraints
+
+ALTER TABLE t3 CHANGE a d INT;
+ERROR HY000: Error on rename of '#sql-temporary' to './test/t3' (errno: 150)
+ALTER TABLE t3 CHANGE b d INT;
+ERROR HY000: Error on rename of '#sql-temporary' to './test/t3' (errno: 150)
+# Ensure that online column rename works.
+ALTER TABLE t3 CHANGE c d INT;
+affected rows: 0
+info: Records: 0  Duplicates: 0  Warnings: 0
+
+# Cleanup.
+
+DROP TABLE t3;
+DROP TABLE t2;
+DROP TABLE t1;
Index: mysql-test/innodb_bug21704.test
===================================================================
--- mysql-test/innodb_bug21704.test	(revision 0)
+++ mysql-test/innodb_bug21704.test	(revision 5488)
@@ -0,0 +1,96 @@
+-- source include/have_innodb.inc
+
+--echo #
+--echo # Bug#21704: Renaming column does not update FK definition.
+--echo #
+
+--echo
+--echo # Test that it's not possible to rename columns participating in a
+--echo # foreign key (either in the referencing or referenced table).
+--echo
+
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+DROP TABLE IF EXISTS t2;
+DROP TABLE IF EXISTS t3;
+--enable_warnings
+
+CREATE TABLE t1 (a INT PRIMARY KEY, b INT) ROW_FORMAT=COMPACT ENGINE=INNODB;
+
+CREATE TABLE t2 (a INT PRIMARY KEY, b INT,
+                 CONSTRAINT fk1 FOREIGN KEY (a) REFERENCES t1(a))
+ROW_FORMAT=COMPACT ENGINE=INNODB;
+
+CREATE TABLE t3 (a INT PRIMARY KEY, b INT, KEY(b), C INT,
+  CONSTRAINT fk2 FOREIGN KEY (b) REFERENCES t3 (a))
+ROW_FORMAT=COMPACT ENGINE=INNODB;
+
+INSERT INTO t1 VALUES (1,1),(2,2),(3,3);
+INSERT INTO t2 VALUES (1,1),(2,2),(3,3);
+INSERT INTO t3 VALUES (1,1,1),(2,2,2),(3,3,3);
+
+--echo
+--echo # Test renaming the column in the referenced table.
+--echo
+
+# mysqltest first does replace_regex, then replace_result
+--replace_regex /'[^']*test\/#sql-[0-9a-f_]*'/'#sql-temporary'/
+# Embedded server doesn't chdir to data directory
+--replace_result $MYSQLTEST_VARDIR . mysqld.1/data/ ''
+--error ER_ERROR_ON_RENAME
+ALTER TABLE t1 CHANGE a c INT;
+
+--echo # Ensure that online column rename works.
+
+--enable_info
+ALTER TABLE t1 CHANGE b c INT;
+--disable_info
+
+--echo
+--echo # Test renaming the column in the referencing table
+--echo
+
+# mysqltest first does replace_regex, then replace_result
+--replace_regex /'[^']*test\/#sql-[0-9a-f_]*'/'#sql-temporary'/
+# Embedded server doesn't chdir to data directory
+--replace_result $MYSQLTEST_VARDIR . mysqld.1/data/ ''
+--error ER_ERROR_ON_RENAME
+ALTER TABLE t2 CHANGE a c INT;
+
+--echo # Ensure that online column rename works.
+
+--enable_info
+ALTER TABLE t2 CHANGE b c INT;
+--disable_info
+
+--echo
+--echo # Test with self-referential constraints
+--echo
+
+# mysqltest first does replace_regex, then replace_result
+--replace_regex /'[^']*test\/#sql-[0-9a-f_]*'/'#sql-temporary'/
+# Embedded server doesn't chdir to data directory
+--replace_result $MYSQLTEST_VARDIR . mysqld.1/data/ ''
+--error ER_ERROR_ON_RENAME
+ALTER TABLE t3 CHANGE a d INT;
+
+# mysqltest first does replace_regex, then replace_result
+--replace_regex /'[^']*test\/#sql-[0-9a-f_]*'/'#sql-temporary'/
+# Embedded server doesn't chdir to data directory
+--replace_result $MYSQLTEST_VARDIR . mysqld.1/data/ ''
+--error ER_ERROR_ON_RENAME
+ALTER TABLE t3 CHANGE b d INT;
+
+--echo # Ensure that online column rename works.
+
+--enable_info
+ALTER TABLE t3 CHANGE c d INT;
+--disable_info
+
+--echo
+--echo # Cleanup.
+--echo
+
+DROP TABLE t3;
+DROP TABLE t2;
+DROP TABLE t1;
Index: handler/ha_innodb.cc
===================================================================
--- handler/ha_innodb.cc	(revision 5487)
+++ handler/ha_innodb.cc	(revision 5488)
@@ -8189,12 +8189,103 @@ innobase_set_cursor_view(
 {
 	read_cursor_set_for_mysql(check_trx_exists(thd),
 				  (cursor_view_t*) curview);
 }
 
 
+/***********************************************************************
+Check whether any of the given columns is being renamed in the table. */
+static
+bool
+column_is_being_renamed(
+/*====================*/
+					/* out: true if any of col_names is
+					being renamed in table */
+	TABLE*		table,		/* in: MySQL table */
+	uint		n_cols,		/* in: number of columns */
+	const char**	col_names)	/* in: names of the columns */
+{
+	uint		j;
+	uint		k;
+	Field*		field;
+	const char*	col_name;
+
+	for (j = 0; j < n_cols; j++) {
+		col_name = col_names[j];
+		for (k = 0; k < table->s->fields; k++) {
+			field = table->field[k];
+			if ((field->flags & FIELD_IS_RENAMED)
+			    && innobase_strcasecmp(field->field_name,
+						   col_name) == 0) {
+				return(true);
+			}
+		}
+	}
+
+	return(false);
+}
+
+/***********************************************************************
+Check whether a column in table "table" is being renamed and if this column
+is part of a foreign key, either part of another table, referencing this
+table or part of this table, referencing another table. */
+static
+bool
+foreign_key_column_is_being_renamed(
+/*================================*/
+					/* out: true if a column that
+					participates in a foreign key definition
+					is being renamed */
+	row_prebuilt_t*	prebuilt,	/* in: InnoDB prebuilt struct */
+	TABLE*		table)		/* in: MySQL table */
+{
+	dict_foreign_t*	foreign;
+
+	/* check whether there are foreign keys at all */
+	if (UT_LIST_GET_LEN(prebuilt->table->foreign_list) == 0
+	    && UT_LIST_GET_LEN(prebuilt->table->referenced_list) == 0) {
+		/* no foreign keys involved with prebuilt->table */
+
+		return(false);
+	}
+
+	row_mysql_lock_data_dictionary(prebuilt->trx);
+
+	/* Check whether any column in the foreign key constraints which refer
+	to this table is being renamed. */
+	for (foreign = UT_LIST_GET_FIRST(prebuilt->table->referenced_list);
+	     foreign != NULL;
+	     foreign = UT_LIST_GET_NEXT(referenced_list, foreign)) {
+
+		if (column_is_being_renamed(table, foreign->n_fields,
+					    foreign->referenced_col_names)) {
+
+			row_mysql_unlock_data_dictionary(prebuilt->trx);
+			return(true);
+		}
+	}
+
+	/* Check whether any column in the foreign key constraints in the
+	table is being renamed. */
+	for (foreign = UT_LIST_GET_FIRST(prebuilt->table->foreign_list);
+	     foreign != NULL;
+	     foreign = UT_LIST_GET_NEXT(foreign_list, foreign)) {
+
+		if (column_is_being_renamed(table, foreign->n_fields,
+					    foreign->foreign_col_names)) {
+
+			row_mysql_unlock_data_dictionary(prebuilt->trx);
+			return(true);
+		}
+	}
+
+	row_mysql_unlock_data_dictionary(prebuilt->trx);
+
+	return(false);
+}
+
 bool ha_innobase::check_if_incompatible_data(
 	HA_CREATE_INFO*	info,
 	uint		table_changes)
 {
 	if (table_changes != IS_EQUAL_YES) {
 
@@ -8205,12 +8296,19 @@ bool ha_innobase::check_if_incompatible_
 	if ((info->used_fields & HA_CREATE_USED_AUTO) &&
 		info->auto_increment_value != 0) {
 
 		return COMPATIBLE_DATA_NO;
 	}
 
+	/* Check if a column participating in a foreign key is being renamed.
+	There is no mechanism for updating InnoDB foreign key definitions. */
+	if (foreign_key_column_is_being_renamed(prebuilt, table)) {
+
+		return COMPATIBLE_DATA_NO;
+	}
+
 	/* Check that row format didn't change */
 	if ((info->used_fields & HA_CREATE_USED_ROW_FORMAT) &&
 		get_row_type() != info->row_type) {
 
 		return COMPATIBLE_DATA_NO;
 	}