MDEV-24763 ALTER TABLE fails to rename a column in SYS_FIELDS

innobase_rename_column_try(): When renaming SYS_FIELDS records
for secondary indexes, try to use both formats of SYS_FIELDS.POS
as keys, in case the PRIMARY KEY includes a column prefix.

Without this fix, an ALTER TABLE that renames a column followed
by a server restart (or LRU eviction of the table definition
from dict_sys) would make the table inaccessible.

mysql-test/suite/innodb/r/alter_table.result

@@ -70,3 +70,19 @@ ERROR HY000: Tablespace has been discarded for table `t`
 ALTER TABLE t FORCE;
 ERROR HY000: Tablespace has been discarded for table `t`
 DROP TABLE t;
+#
+# MDEV-24763 ALTER TABLE fails to rename a column in SYS_FIELDS
+#
+CREATE TABLE t1 (a INT, b TEXT, c INT, PRIMARY KEY(b(9)), INDEX(c,a))
+ENGINE=InnoDB;
+ALTER TABLE t1 CHANGE COLUMN a u INT;
+SELECT sf.* FROM information_schema.innodb_sys_fields sf
+INNER JOIN information_schema.innodb_sys_indexes si ON sf.index_id=si.index_id
+INNER JOIN information_schema.innodb_sys_tables st ON si.table_id=st.table_id
+WHERE st.name='test/t1' ORDER BY pos;
+INDEX_ID	NAME	POS
+ID	b	0
+ID	c	0
+ID	u	1
+DROP TABLE t1;
+# End of 10.2 tests

mysql-test/suite/innodb/t/alter_table.test

@@ -79,3 +79,18 @@ ALTER TABLE t ENGINE INNODB;
 --error ER_TABLESPACE_DISCARDED
 ALTER TABLE t FORCE;
 DROP TABLE t;
+
+--echo #
+--echo # MDEV-24763 ALTER TABLE fails to rename a column in SYS_FIELDS
+--echo #
+CREATE TABLE t1 (a INT, b TEXT, c INT, PRIMARY KEY(b(9)), INDEX(c,a))
+ENGINE=InnoDB;
+ALTER TABLE t1 CHANGE COLUMN a u INT;
+--replace_column 1 ID
+SELECT sf.* FROM information_schema.innodb_sys_fields sf
+INNER JOIN information_schema.innodb_sys_indexes si ON sf.index_id=si.index_id
+INNER JOIN information_schema.innodb_sys_tables st ON si.table_id=st.table_id
+WHERE st.name='test/t1' ORDER BY pos;
+DROP TABLE t1;
+
+--echo # End of 10.2 tests

storage/innobase/handler/handler0alter.cc

@@ -6734,6 +6734,7 @@ innobase_rename_column_try(
 {
 	pars_info_t*	info;
 	dberr_t		error;
+	bool clust_has_prefixes = false;
 
 	DBUG_ENTER("innobase_rename_column_try");
 
@@ -6822,6 +6823,39 @@ innobase_rename_column_try(
 			if (error != DB_SUCCESS) {
 				goto err_exit;
 			}
+
+			if (!has_prefixes || !clust_has_prefixes
+			    || field->prefix_len) {
+				continue;
+			}
+
+			/* For secondary indexes, the
+			has_prefixes check can be 'polluted'
+			by PRIMARY KEY column prefix. Try also
+			the simpler encoding of SYS_FIELDS.POS. */
+			info = pars_info_create();
+
+			pars_info_add_ull_literal(info, "indexid", index->id);
+			pars_info_add_int4_literal(info, "nth", i);
+			pars_info_add_str_literal(info, "new", to);
+
+			error = que_eval_sql(
+				info,
+				"PROCEDURE RENAME_SYS_FIELDS_PROC () IS\n"
+				"BEGIN\n"
+				"UPDATE SYS_FIELDS SET COL_NAME=:new\n"
+				"WHERE INDEX_ID=:indexid\n"
+				"AND POS=:nth;\n"
+				"END;\n",
+				FALSE, trx);
+
+			if (error != DB_SUCCESS) {
+				goto err_exit;
+			}
+		}
+
+		if (index == dict_table_get_first_index(user_table)) {
+			clust_has_prefixes = has_prefixes;
 		}
 	}