Question

On my virtual dedicated linux server, there are always some php jobs running. These jobs keep writing data in different tables. I was wondering, what happens if i need to restart my mysql server as i have made some config changes? Will all the running jobs be killed if i restart my mysql server ? or will they be on hold for a while , throwing error while the server is being restarted?

Thanks for your help

Answer 1

If you put a bit of code around the actual mysql php calls, you can catch the errors and deal with them.

function mquery( $qry, $lnk ) {
global $dbl;  # your pre-established database link

$result = mysql_query( $qry, $lnk );

if ( $result === false ) {
    $error_msg = mysql_error( $lnk );

    while ( $result === false && @$i < 25 ) {
        $i++;

        $error_no  = mysql_errno( $lnk );

        if      ( $error_no == 1054 ||  # "MySQL Error #1054: Unknown column..."
                     $error_no == 1064 ||  # "You have an error in your SQL syntax" - MAC - May 30, 2012
                     $error_no == 1065 ) { # "Query was empty" 
            break;  # don't loop on errors - it will not succeed
        }
        else if ( $error_no == 1205 ||  # SQLSTATE[HY000]: General error: 1205 Lock wait timeout exceeded; try restarting transaction
                     $error_no == 1213 ) { # "Deadlock found when trying to get lock; try restarting transaction" 
            sleep( $i );                 # try sleeping a bit longer to get past the deadlock
        }
        else if ( $error_no == 2003 ||  # SQLSTATE[HY000] [2003] Can't connect to MySQL server
                     $error_no == 2006 ||  # "MySQL server has gone away" -- reconnect 
                     $error_no == 2013 ) { # SQLSTATE[HY000] [2013] Lost connection to MySQL server at 'reading authorization packet', system error: 0
            sleep( $i );
            if      ( $lnk == $dbl )    { # you may have multiple database links...
                get_dbl();   # re-establish your database link
                $lnk = $dbl;
            }
        }
        else {
            sleep( 1 ); # keeps us from sleeping too long on other errors
        }

        $result = mysql_query( $qry, $lnk );
    }
    echo "\n<!-- MySQL Error #$error_no: '$error_msg' (tried $i times) -->\n";
}

return $result;

}
// end mquery

If you find that you have other errors that may succeed if you wait a little while, then add them.

For errors that won’t succeed no matter how long you wait, add them to the ‘break’ block of code.