[syslog-ng] log messages lost

[Luigi Augello]

hello
I use  syslog-ng and it sends log in a local Mysql database  via pipe and I have
this syslog.conf

options { flush_lines(0);
          time_reopen (10);
          log_fifo_size (1000);
          long_hostnames (off);
          use_dns (yes);
          dns_cache(yes);
          dns_cache_size(2000);
          use_fqdn (yes);
          create_dirs (no);
          keep_hostname (yes);
	  time_reopen (10);
        };

source src { unix-stream("/dev/log"); internal(); };
source src_firewall { file ("/proc/kmsg" log_prefix("firewall: ")); };
filter firewal_filter     { match("REJECT"); };

destination d_mysql {
pipe("/tmp/mysql.pipe"
template("INSERT INTO logs (host, facility, priority, level, tag, date,
time, program, msg) VALUES ( '$HOST', '$FACILITY', '$PRIORITY', '$LEVEL','$TAG',
'$YEAR-$MONTH-$DAY', '$HOUR:$MIN:$SEC', '$PROGRAM', '$MSG' );\n") 
template-escape(yes));
};
log { source(src); destination(d_mysql); };
log { source(src_firewall); destination(d_mysql); };

sometimes in the database i found this msg record

syslog-ng[6130]: Log statistics; dropped='pipe(/tmp/mysql.pipe)=0',
processed='center(queued)=57298', processed='center(received)=57298',
processed='destination(d_mysql)=57298',
processed='source(src_firewall)=51537', processed='source(src)=5761'

I assume that this message advises that some logs are lost. I register the
messages only local and that messages that i register include firewall's 
messages. It is possible solve this problem, which configuration I could use
to solve this problem?

tanks a lot
Luigi