Question

i was trying to enable slow_query_log. i have downloaded my.cnf file from server using WinSCP and added the code for enabling slow_query_log.

slow_query_log = ON
slow_query_log_file = /var/log/mysql_slow.log

And when i restart my server i am getting this error mysql has failed, please contact the sysadmin (result was "mysql is not running").
here i am adding my my.cnf file
i have tried with slow_query_log = 1 also. But getting the same error. when i remove the code which i have added the error is gone. Any one please help me…

my.cnf

    [mysqld]
datadir=/home/mysql/
tmpdir=/home/mysqltmp
#max_connections = 175 #was 175
max_connections = 80
#max_connect_errors = 350 #was 250
max_connect_errors = 250
safe-show-database
skip-locking
key_buffer = 1024M # was 128M
max_allowed_packet = 6M
myisam_sort_buffer_size = 64M

#old settings, for 900 ish max maxconn
#sort_buffer_size = 32M
#read_buffer_size = 32M
#read_rnd_buffer_size = 32M

sort_buffer_size = 5M
read_buffer_size = 5M
read_rnd_buffer_size = 5M

query_cache_size= 1024M
query_cache_limit= 16M
max_heap_table_size = 128M
tmp_table_size = 128M
thread_concurrency = 16
wait_timeout = 10
innodb_file_per_table
innodb_log_file_size = 10485760
open_files_limit = 8192
low_priority_updates = 1 
slow_query_log = ON
slow_query_log_file = /var/log/mysql_slow.log

# who set these? these are NOT memory settings, but rather integer settings.
#table_cache = 1024M
#thread_cache_size = 8M

table_cache = 512
thread_cache_size = 8

[mysqldump]
quick
max_allowed_packet = 16M

[mysql]
no-auto-rehash

[isamchk]
key_buffer = 128M
sort_buffer_size = 128M
read_buffer = 2M
write_buffer = 2M

[myisamchk]
key_buffer = 128M
sort_buffer_size = 128M
read_buffer = 2M
write_buffer = 2M

Answer 1

create the file mysql_slow.log in /var/log & change ownerhip of the file:

chown mysql.mysql -R /var/log/mysql_slow.log

either value (1 or ON) should work for the slow query log.

also, are you using regular statements?