I figured out the problem. I have to use "host="127.0.0.1" to force it using TCP connection. I have tried "(host="localhost", port=("3306")" and it didn't work neither. I guess it is hard coded to use socket for localhost which seems reasonable.
There is a related question on this. If I want to use socket connection, how can I specify the socket file? It is by default using "/var/run/mysqld/mysqld.sock" which is different than the one in RHEL.

-----Original Message-----
From: Arnold Wang <arnold.wang@inovis.com>
To: syslog-ng@lists.balabit.hu
Subject: Re: syslog-ng 3.0.1, open source edition, fails write to MySQL DB
Date: Thu, 23 Apr 2009 13:06:55 -0700

After I posted to the list, first I did when I run into this problem, I enabled the debug and noticed the following error:
Apr 23 15:58:15 alfnetengi01 syslog-ng[7826]: Error establishing SQL connection; type='mysql', host='localhost', port='', username='syslogadmin', database='syslog', error='2002: Can\'t connect to local MySQL server through socket \'/var/run/mysqld/mysqld.sock\' (2)'
It appears to me it try to connect to MySQL using sock instead of TCP, as I original assumed. Is there a way to use TCP connection? I will play around as well.
Thanks.

-----Original Message-----
From: Arnold Wang <arnold.wang@inovis.com>
To: syslog-ng@lists.balabit.hu
Subject: syslog-ng 3.0.1, open source edition, fails write to MySQL DB
Date: Thu, 23 Apr 2009 12:35:07 -0700

I have installed syslog-ng 3.0.1, open source edition, binary package in RHEL 5.3 system. I'm having trouble to have it writing to MySQL DB using native driver. The current configuration file looks like:
# Write the logs to MySQL DB
destination dd_mysql {
sql(type(mysql)
host("localhost") username("syslogadmin") password("syslogadmin")
database("syslog")
table("logs")
columns("host", "facility", "priority", "level", "tag", "datetime", "program", "msg", "seq")
values("$HOST", "$FACILITY", "$PRIORITY", "$LEVEL", "$TAG", "$YEAR-$MONTH-$DAY $HOUR:$MIN:$SEC", "$PROGRAM", "$MSG", "$SEQ")
indexes("seq"));
# program("/usr/bin/mysql -usyslogadmin -psyslogadmin syslog"
# template("INSERT INTO logs (host, facility, priority, level, tag, datetime, program, msg, seq)
# VALUES ( '$HOST', '$FACILITY', '$PRIORITY', '$LEVEL', '$TAG', '$YEAR-$MONTH-$DAY $HOUR:$MIN:$SEC', '$PROGRAM', '$MSG', '$SEQ' );\n")
# template-escape(yes));
};
It works if I use the program driver, as currently commented out.
The table is configured as following, using the schema defined by php-syslog-ng 2.9.8m.
+----------+---------------------+------+-----+---------+----------------+
| Field    | Type                | Null | Key | Default | Extra          |
+----------+---------------------+------+-----+---------+----------------+
| id       | bigint(20) unsigned | NO   | PRI | NULL    | auto_increment |
| host     | varchar(128)        | YES  | MUL | NULL    |                |
| facility | varchar(10)         | YES  | MUL | NULL    |                |
| priority | varchar(10)         | YES  | MUL | NULL    |                |
| level    | varchar(10)         | YES  |     | NULL    |                |
| tag      | varchar(10)         | YES  |     | NULL    |                |
| datetime | datetime            | YES  | MUL | NULL    |                |
| program  | varchar(15)         | YES  | MUL | NULL    |                |
| msg      | text                | YES  |     | NULL    |                |
| seq      | bigint(20) unsigned | NO   | MUL | 0       |                |
| counter  | int(11)             | NO   |     | 1       |                |
| fo       | datetime            | YES  |     | NULL    |                |
| lo       | datetime            | YES  |     | NULL    |                |
+----------+---------------------+------+-----+---------+----------------
What is the problem?
Thanks in advance for the help.