Bug#20198490 : LOWER_CASE_TABLE_NAMES=0 ON WINDOWS LEADS TO

               PROBLEMS

Description:- Server variable "--lower_case_tables_names"
when set to "0" on windows platform which does not support
case sensitive file operations leads to problems. A warning
message is printed in the error log while starting the
server with "--lower_case_tables_names=0". Also according to
the documentation, seting "lower_case_tables_names" to "0"
on a case-insensitive filesystem might lead to index
corruption.

Analysis:- The problem reported in the bug is:-
Creating an INNODB table 'a' and executing a query, "INSERT
INTO a SELECT a FROM A;" on a server started with
"--lower_case_tables_names=0" and running on a
case-insensitive filesystem leads innodb to flat spin.
Optimizer thinks that "a" and "A" are two different tables
as the variable "lower_case_table_names" is set to "0". As a
result, optimizer comes up with a plan which does not need a
temporary table. If the same table is used in select and
insert, a temporary table is needed. This incorrect
optimizer plan leads to infinite insertions.

Fix:- If the server is started with
"--lower_case_tables_names" set to 0 on a case-insensitive
filesystem, an error, "The server option
'lower_case_table_names'is configured to use case sensitive
table names but the data directory is on a case-insensitive
file system which is an unsupported combination. Please
consider either using a case sensitive file system for your
data directory or switching to a case-insensitive table name
mode.", is printed in the server error log and the server
exits.

2 files changed, 3 insertions, 11 deletions

diff --git a/mysql-test/r/lowercase_fs_on.result b/mysql-test/r/lowercase_fs_on.result
new file mode 100644
index 00000000000..a090f46cfbf
--- /dev/null
+++ b/mysql-test/r/lowercase_fs_on.result
@@ -0,0 +1,3 @@
+#
+# Bug#20198490 : LOWER_CASE_TABLE_NAMES=0 ON WINDOWS LEADS TO PROBLEMS
+#
diff --git a/mysql-test/r/lowercase_table3.result b/mysql-test/r/lowercase_table3.result
deleted file mode 100644
index 22e80aaeb26..00000000000
--- a/mysql-test/r/lowercase_table3.result
+++ /dev/null
@@ -1,11 +0,0 @@
-call mtr.add_suppression("Cannot find or open table test/BUG29839 from");
-DROP TABLE IF EXISTS t1,T1;
-CREATE TABLE t1 (a INT);
-SELECT * FROM T1;
-a
-FLUSH TABLES;
-DROP TABLE t1;
-CREATE TABLE bug29839 (a INT) ENGINE=INNODB;
-SELECT * FROM BUG29839;
-ERROR 42S02: Table 'test.BUG29839' doesn't exist
-DROP TABLE bug29839;