lower_case_table_names Settings in MySQL 8.0.12 - mysql

Question

I've just compiled the version MySQL 8.0.12 in a Ubuntu 16.0.4.
After following the instructions in the website and making the following my.cnf file:
[mysqld]
datadir=/usr/local/mysql/data
socket=/tmp/mysql.sock
port=3306
log-error=/usr/local/mysql/data/localhost.localdomain.err
user=mysql
secure_file_priv=/usr/local/mysql/mysql-files
local_infile=OFF
log_error = /var/log/mysql/error.log
# Remove case sensitive in table names
lower_case_table_names=1
I get the following error:
2018-08-11T19:45:06.461585Z 1 [ERROR] [MY-011087] [Server] Different lower_case_table_names settings for server ('1') and data dictionary ('0').
What should I change so that data dictionary is aligned to server settings?

Answer 1

So far, I can get it to work with a workaround (I originally posted on askubuntu): by re-initializing MySQL with the new value for lower_case_table_names after its installation. The following steps apply to a new installation. If you have already data in a database, export it first to import it back later:
Install MySQL:
sudo apt-get update
sudo apt-get install mysql-server -y
Stop the MySQL service:
sudo service mysql stop
Delete the MySQL data directory:
sudo rm -rf /var/lib/mysql
Recreate the MySQL data directory (yes, it is not sufficient to just delete its content):
sudo mkdir /var/lib/mysql
sudo chown mysql:mysql /var/lib/mysql
sudo chmod 700 /var/lib/mysql
Add lower_case_table_names = 1 to the [mysqld] section in /etc/mysql/mysql.conf.d/mysqld.cnf.
Re-initialize MySQL with --lower_case_table_names=1:
sudo mysqld --defaults-file=/etc/mysql/my.cnf --initialize --lower_case_table_names=1 --user=mysql --console
Start the MySQL service:
sudo service mysql start
Retrieve the new generated password for MySQL user root:
sudo grep 'temporary password' /var/log/mysql/error.log
Change the password of MySQL user root either by:
sudo mysql -u root -p
and executing:
ALTER USER 'root'#'localhost' IDENTIFIED BY 'MyNewPa$$w0rd';
afterwards, OR by calling the "hardening" script anyway:
sudo mysql_secure_installation
After that, you can verify the lower_case_table_names setting by entering the MySQL shell:
sudo mysql -u root -p
and executing:
SHOW VARIABLES LIKE 'lower_case_%';
Expected output:
+------------------------+-------+
| Variable_name | Value |
+------------------------+-------+
| lower_case_file_system | OFF |
| lower_case_table_names | 1 |
+------------------------+-------+

Answer 2

As per this link, lower_case_table_names should be set together with --initialize option.

Answer 3

MySQL Documentation says
lower_case_table_names can only be configured while initializing the server. Changing the lower_case_table_names setting after the server is initialized is prohibited.
https://dev.mysql.com/doc/refman/8.0/en/identifier-case-sensitivity.html

Answer 4

The best way to prevent this problem is :At first add
[mysqld]
lower_case_table_names=1
then start mysql service for first time.
But anyway if you have started the server already,to solve your problem:
1.stop mysql:
systemctl stop mysql
2.clean data directory or change the default, the following is for new installations , if you have data in your database BACK UP them beforehand
rm -rf /var/lib/mysql
3.Insert lower_case_table_names = 1 in your my.cnf:
[mysqld]
lower_case_table_names=1
4.Start again
systemctl start mysqld

Answer 5

To fix this issue,
Just take the backup of the existing db Schema using the following command inside bin folder (/usr/local/mysql/bin)
./mysqldump -uroot -p password > dump.sql
Once the backup is taken delete the existing data folder in Mysql Home(/usr/local/mysql/) using the command
rm -rf data
Now add the configuration as "lower_case_table_names=1" in my.cnf under MYSQLD section (/etc/my.cnf)
Now Initialize the data directory using the following command inside bin directory (/usr/local/mysql/bin)
For Secure mode
./mysqld --defaults-file=/etc/my.cnf --initialize --user=mysql --console
For Insecure mode
./mysqld --defaults-file=/etc/my.cnf --initialize-insecure --user=mysql --console
Once the data directory initialized, For Insecure mode repeat the Installation again and For Secure mode use the root password which is initialized during the run time of data directory Initialization.
Now import the existing dump file inside the Mysql Server using the command inside (/usr/local/mysql/bin) directory
./mysql -uroot -p password < file.sql

Answer 6

If anyone runs into this issue now, if you already initialized mysql, meaning you already had it up and running and then this error occurred, just comment out this line in the my.ini file.
lower_case_table_names=