Andrew Beaton :: FAQ » MySQL

Can’t create table – errno: 13

Andrew — Wed, 30 Dec 2009 16:19:22 +0000

I came across a problem today when trying to create a temporary table in MySQL.

ERROR 1005 (HY000): Can't create table 'temptable' (errno: 13)

The first thing I checked was that the user in question had the Create_tmp_table_priv privilege in the users table, which it did.

The next step was to find out where MySQL was writing the temporary tables.

The following command tells us this:

show variables like '%dir';
+---------------------------+----------------------------+
| Variable_name             | Value                      |
+---------------------------+----------------------------+
| basedir                   | /usr/                      |
| bdb_logdir                |                            |
| bdb_tmpdir                | /tmp/                      |
| character_sets_dir        | /usr/share/mysql/charsets/ |
| datadir                   | /var/lib/mysql/            |
| innodb_data_home_dir      |                            |
| innodb_log_arch_dir       |                            |
| innodb_log_group_home_dir | ./                         |
| slave_load_tmpdir         | /tmp/                      |
| tmpdir                    | /tmp/                      |
+---------------------------+----------------------------+

And from that we see the tmpdir is located in /tmp/.

A quick checked revealed that MySQL could not create files in this directory, no write access, so a simple permissions change and all was well again.

Backup a MySQL database

Andrew — Fri, 27 Nov 2009 20:10:24 +0000

I’ll just quickly cover some options here to backup a MySQL database.

The first will output all the data and all the databases along with the schema:

mysqldump -u <user> -p -h <hostname> --all-databases > all_databases.sql

The next option will output just the schema for all of the databases:

mysqldump -d -u <user> -p -h <hostname> --all-databases > all_databases.sql

Now we can use the same two methods above but replace –all-databases with the name of a database to output just one.

Recover MySQL password

Andrew — Fri, 13 Nov 2009 22:52:07 +0000

You can recover MySQL database server password with following five easy steps.

Here are commands you need to type for each step (login as the root user):

Stop mysql service
Start to MySQL server w/o password:
Connect to mysql server using mysql client:
Setup new MySQL root user password
Stop MySQL Server:
Start MySQL server and test it

Step # 1 : Stop mysql service

# /etc/init.d/mysql stop

Output:

Stopping MySQL database server: mysqld.

Step # 2: Start to MySQL server w/o password:

# mysqld_safe --skip-grant-tables &

Output:

[1] 1058
Starting mysqld daemon with databases from /var/lib/mysql
mysqld_safe[6025]: started

Step # 3: Connect to mysql server using mysql client:

# mysql -u root

Output:

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1 to server version: 4.1.15-Debian_1-log
 
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
 
mysql>

Step # 4: Setup new MySQL root user password

mysql> use mysql;
mysql> update user set password=PASSWORD("NEW-ROOT-PASSWORD") where User='root';
mysql> flush privileges;
mysql> quit

Step # 5: Stop MySQL Server:

# /etc/init.d/mysql stop

Output:

Stopping MySQL database server: mysqld
STOPPING server from pid file /var/run/mysqld/mysqld.pid
mysqld_safe[6186]: ended
 
[1]+  Done                    mysqld_safe --skip-grant-tables

Step # 6: Start MySQL server and test it

# /etc/init.d/mysql start
# mysql -u root -p