Ruby Forum Ruby on Rails > Mysql::Error: Lost connection to MySQL server during query:

Hi,

I am having Mysql connection problem for my first AddressBook 
application (which I took it from 
http://www-128.ibm.com/developerworks/linux/library/l-rubyrails/)

I have gem installed the latest ruby, rails, lighttpd, fastcgi, 
mysql-4.1.14 on linux. Everything looks good. When I do:

mysql -h localhost -u test -ptest -D AddressBook
mysql> SELECT COUNT(*) FROM contacts;
+----------+
| COUNT(*) |
+----------+
|        1 |
+----------+
1 row in set (0.00 sec)

And I have config/database.yml as

development:
  adapter: mysql
  database: AddressBook
  username: test
  password: test
  #socket: /var/lib/mysql/mysql.sock

  # Connect on a TCP socket.  If omitted, the adapter will connect on 
the
  # domain socket given by socket instead.
  host: localhost
  port: 3306


Here's the stack trace:
  Parameters: {"action"=>"index", "controller"=>"contact"}
  Contact Count (0.000000)   Mysql::Error: Lost connection to MySQL 
server during query: SELECT COUNT(*) FROM contacts


ActiveRecord::StatementInvalid (Mysql::Error: Lost connection to MySQL 
server during query: SELECT COUNT(*) FROM contacts ):
    /home/aaronlee/ruby/gemrepository/gems/activerecord-1.13.2/lib/active_record/connection_adapters/abstract_adapter.rb:88:in 
`log'
    /home/aaronlee/ruby/gemrepository/gems/activerecord-1.13.2/lib/active_record/connection_adapters/mysql_adapter.rb:180:in 
`execute'
    /home/aaronlee/ruby/gemrepository/gems/activerecord-1.13.2/lib/active_record/connection_adapters/mysql_adapter.rb:322:in 
`select'
    /home/aaronlee/ruby/gemrepository/gems/activerecord-1.13.2/lib/active_record/connection_adapters/mysql_adapter.rb:175:in 
`select_one'
    /home/aaronlee/ruby/gemrepository/gems/activerecord-1.13.2/lib/active_record/connection_adapters/abstract/database_statements.rb:16:in 
`select_value'
    /home/aaronlee/ruby/gemrepository/gems/activerecord-1.13.2/lib/active_record/base.rb:518:in 
`count_by_sql'
    /home/aaronlee/ruby/gemrepository/gems/activerecord-1.13.2/lib/active_record/base.rb:511:in 
`count'
    /home/aaronlee/ruby/gemrepository/gems/actionpack-1.11.2/lib/action_controller/pagination.rb:167:in 
`count_collection_for_pagination'
    /home/aaronlee/ruby/gemrepository/gems/actionpack-1.11.2/lib/action_controller/pagination.rb:188:in 
`paginator_and_collection_for'
    /home/aaronlee/ruby/gemrepository/gems/actionpack-1.11.2/lib/action_controller/pagination.rb:124:in 
`paginate'
    /home/aaronlee/ruby/gemrepository/gems/actionpack-1.11.2/lib/action_controller/scaffolding.rb:101:in 
`list'
    /home/aaronlee/ruby/gemrepository/gems/actionpack-1.11.2/lib/action_controller/scaffolding.rb:94:in 
`index'
    /home/aaronlee/ruby/gemrepository/gems/actionpack-1.11.2/lib/action_controller/base.rb:853:in 
`perform_action_without_filters'
    /home/aaronlee/ruby/gemrepository/gems/actionpack-1.11.2/lib/action_controller/filters.rb:332:in 
`perform_action_without_benchmark'
    /home/aaronlee/ruby/gemrepository/gems/actionpack-1.11.2/lib/action_controller/benchmarking.rb:69:in 
`perform_action_without_rescue'
    /home/aaronlee/ruby/install-1.8.4//lib/ruby/1.8/benchmark.rb:293:in 
`measure'
    /home/aaronlee/ruby/gemrepository/gems/actionpack-1.11.2/lib/action_controller/benchmarking.rb:69:in 
`perform_action_without_rescue'
    /home/aaronlee/ruby/gemrepository/gems/actionpack-1.11.2/lib/action_controller/rescue.rb:82:in 
`perform_action'
    /home/aaronlee/ruby/gemrepository/gems/actionpack-1.11.2/lib/action_controller/base.rb:369:in 
`process_without_session_management_support'
    /home/aaronlee/ruby/gemrepository/gems/actionpack-1.11.2/lib/action_controller/session_management.rb:116:in 
`process'
    /home/aaronlee/ruby/gemrepository/gems/rails-1.0.0/lib/dispatcher.rb:38:in 
`dispatch'
    /home/aaronlee/ruby/gemrepository/gems/rails-1.0.0/lib/fcgi_handler.rb:141:in 
`process_request'
    /home/aaronlee/ruby/gemrepository/gems/rails-1.0.0/lib/fcgi_handler.rb:53:in 
`process!'
    /home/aaronlee/ruby/install-1.8.4//lib/ruby/site_ruby/1.8/fcgi.rb:600:in 
`each_cgi'
    /home/aaronlee/ruby/install-1.8.4//lib/ruby/site_ruby/1.8/fcgi.rb:597:in 
`each_cgi'
    /home/aaronlee/ruby/gemrepository/gems/rails-1.0.0/lib/fcgi_handler.rb:52:in 
`process!'
    /home/aaronlee/ruby/gemrepository/gems/rails-1.0.0/lib/fcgi_handler.rb:22:in 
`process!'
    /home/aaronlee/ruby/AddressBook/public/dispatch.fcgi:24


Any ideas? How do I go about debugging this problem? Can I have a more 
verbose mode to know whether it's talking to my localhost MySQL?

-Aaron

One more data point: if I start with ruby script/server webrick I 
actuall got

/home/aaronlee/ruby/gemrepository/gems/activerecord-1.13.2/lib/active_record/connection_adapters/mysql_adapter.rb:325: 
[BUG] Segmentation fault
ruby 1.8.4 (2005-12-24) [i686-linux]

Aborted

-Aaron

Try the socket method instead of TCP...

verify that is the location of the socket...
# ls -l /var/lib/mysql/mysql.sock
srwxrwxrwx  1 mysql mysql 0 Jan 26 21:53 /var/lib/mysql/mysql.sock

There may be a firewall interfering...

or try command line connecting to TCP Port 3306...

I think it's something like...

mysql -h localhost -P 3306 -u test -ptest -D AddressBook

and lastly...newer versions of mysql sometimes default to older password
version hash which has bit many people...

# cat /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Default to using old password format for compatibility with mysql 3.x
# clients (those using the mysqlclient10 compatibility package).
old_passwords=0
...

As you can see...I changed it from '1' to '0' as Red Hat stuff defaults
to 'old password' and that didn't play well with Rails.

As for 'debugging' mysql, I don't know much besides looking at logs
log/development.log - mysqld.log or ethereal trace - perhaps someone
else can offer some suggestions.

Craig

On Wed, 2006-02-08 at 06:37 +0100, Aaron Lee wrote:
> One more data point: if I start with ruby script/server webrick I 
> actuall got
> 
> /home/aaronlee/ruby/gemrepository/gems/activerecord-1.13.2/lib/active_record/connection_adapters/mysql_adapter.rb:325: 
> [BUG] Segmentation fault
> ruby 1.8.4 (2005-12-24) [i686-linux]
> 
> Aborted
> 
----
I don't know that this is going to help but at the top of of
database.yml...it should be stating some important details...

# Get the fast C bindings:
#   gem install mysql
#   (on OS X: gem install mysql -- --include=/usr/local/lib)
# And be sure to use new-style password hashing:
#   http://dev.mysql.com/doc/refman/5.0/en/old-client.html

did you do 'gem install mysql' ?

also - no tabs in database.yml (I think this has also been discussed on
this message base a time or two).

Seg fault though sounds like something else is the problem.

Craig

Craig White wrote:
> Try the socket method instead of TCP...
> 

I tried both and both failed. I also ran gem install mysql (2.7)
I also tried creating a new user ruby without password and that also 
failed with the same Mysql::Error Lost connection ...

development:
  adapter: mysql
  database: AddressBook
  username: test
  password: test
  socket: /var/lib/mysql/mysql.sock

AND

development:
  adapter: mysql
  database: AddressBook
  username: test
  password: test
  host: localhost
  port: 3306

> verify that is the location of the socket...
> # ls -l /var/lib/mysql/mysql.sock
> srwxrwxrwx  1 mysql mysql 0 Jan 26 21:53 /var/lib/mysql/mysql.sock
> 

It's there

> There may be a firewall interfering...
> 
> or try command line connecting to TCP Port 3306...
> 
> I think it's something like...
> 
> mysql -h localhost -P 3306 -u test -ptest -D AddressBook
> 

This one works so I am pretty sure it's no problem. Talking to localhost 
doesn't go through firewall

> and lastly...newer versions of mysql sometimes default to older password
> version hash which has bit many people...
> 
> # cat /etc/my.cnf
> [mysqld]
> datadir=/var/lib/mysql
> socket=/var/lib/mysql/mysql.sock
> # Default to using old password format for compatibility with mysql 3.x
> # clients (those using the mysqlclient10 compatibility package).
> old_passwords=0
> ...
> 

I changed old_passwords from 1 to 0 and did  /etc/init.d/mysqld restart
but it still doesn't help

> As you can see...I changed it from '1' to '0' as Red Hat stuff defaults
> to 'old password' and that didn't play well with Rails.
> 
> As for 'debugging' mysql, I don't know much besides looking at logs
> log/development.log - mysqld.log or ethereal trace - perhaps someone
> else can offer some suggestions.
> 
> Craig


/var/log/mysql.log shows

/usr/libexec/mysqld: ready for connections.
Version: '4.1.14'  socket: '/var/lib/mysql/mysql.sock'  port: 3306 
Source distribution

Any other ideas? -Aaron

The following works (I forgot to reran the new mysql password 
generation).

mysql> grant all privileges on *.* to 'test'@'localhost' identified by 
'test' with grant option;
mysql> flush privileges;

Thanks!
Aaron

I had a MySQL error this was a gr8 help

http://www.fixya.com/support/t840251-mysql_error_messeage

I hope this will help you,
Yuri.