[#MDEV-25749] DROP DATABASE in InnoDB is case-insensitive

Table names are supposed to be case-sensitive on a case-sensitive file system. Alas, as noted in ~~MDEV-25748~~, DROP DATABASE would seem drop InnoDB tables in a case-insensitive fashion, affecting tables in databases whose name only differs in the letter case:

diff --git a/mysql-test/suite/innodb/t/alter_foreign_crash.test b/mysql-test/suite/innodb/t/alter_foreign_crash.test

index 1952a1b30d4..b65dfa175c2 100644

--- a/mysql-test/suite/innodb/t/alter_foreign_crash.test

+++ b/mysql-test/suite/innodb/t/alter_foreign_crash.test

@@ -2,6 +2,7 @@

 --source include/have_debug_sync.inc

 # The embedded server does not support restarting.

 --source include/not_embedded.inc

+--source include/have_case_sensitive_file_system.inc

 --echo #

 --echo # Bug #20476395 DICT_LOAD_FOREIGNS() FAILED IN

@@ -10,6 +11,11 @@

 call mtr.add_suppression("InnoDB: Failed to load table");

+CREATE DATABASE Bug;

+CREATE TABLE Bug.parent(a SERIAL) ENGINE=INNODB;

+CREATE TABLE Bug.child(a SERIAL, FOREIGN KEY f(a) REFERENCES Bug.parent(a))

+ENGINE=INNODB;

 create database bug;

 use bug;

@@ -18,6 +24,7 @@ create table child(a serial, foreign key fk (a) references parent(a))engine=inno

 insert into parent values(1);

 insert into child values(1);

+drop database Bug;

 connect (con1,localhost,root,,bug);

 SET DEBUG_SYNC='innodb_rename_table_ready SIGNAL s1 WAIT_FOR s2 EXECUTE 2';

@@ -32,6 +39,9 @@ disconnect con1;

 show tables;

 alter table parent row_format=dynamic;

+select * from child;

+--error ER_ROW_IS_REFERENCED_2

+drop table parent;

+drop table child;

 drop table parent;

 drop database bug;

The changed test would fail in an unexpected way (not a mere result difference):

10.2 629449172a5b0a6975663ca1ac420789e00b941d
CURRENT_TEST: innodb.alter_foreign_crash
mysqltest: At line 42: query 'select * from child' failed: 1146: Table 'bug.child' doesn't exist

Possibly we could fix this by porting the fixes of ~~MDEV-25691~~ and ~~MDEV-25748~~ from MariaDB Server 10.6, but it might not be a good idea because the ~~MDEV-25691~~ fix removes work-arounds for the lack of atomic DDL (~~MDEV-17567~~).

Hence, even though I usually treat InnoDB corruption bugs at high priority, I am only filing this bug for documenting its existence. I do not plan to fix this, because the fix could cause more damage, and because the bug has existed for years without anyone complaining.

[MDEV-25749] DROP DATABASE in InnoDB is case-insensitive Created: 2021-05-21 Updated: 2022-06-13 Resolved: 2021-07-23
Status:	Closed
Project:	MariaDB Server
Component/s:	Storage Engine - InnoDB
Affects Version/s:	10.2, 10.3, 10.4, 10.5
Fix Version/s:	10.6.2

[MDEV-25749] DROP DATABASE in InnoDB is case-insensitive Created: 2021-05-21 Updated: 2022-06-13 Resolved: 2021-07-23