This is the multi-page printable view of this section. Click here to print.

Return to the regular view of this page.

sql() destination options

This driver sends messages into an SQL database. The sql() destination has the following options:

batch-bytes()


Accepted values:	number [bytes]
Default:	none

Description: Sets the maximum size of payload in a batch. If the size of the messages reaches this value, AxoSyslog sends the batch to the destination even if the number of messages is less than the value of the batch-lines() option.

Note that if the batch-timeout() option is enabled and the queue becomes empty, AxoSyslog flushes the messages only if batch-timeout() expires, or the batch reaches the limit set in batch-bytes().

Available in AxoSyslog version 3.19 and later.

batch-lines()


Type:	number
Default:	1

Description: Specifies how many lines are flushed to a destination in one batch. The AxoSyslog application waits for this number of lines to accumulate and sends them off in a single batch. Increasing this number increases throughput as more messages are sent in a single batch, but also increases message latency.

For example, if you set batch-lines() to 100, AxoSyslog waits for 100 messages.

If the batch-timeout() option is disabled, the AxoSyslog application flushes the messages if it has sent batch-lines() number of messages, or the queue became empty. If you stop or reload AxoSyslog or in case of network sources, the connection with the client is closed, AxoSyslog automatically sends the unsent messages to the destination.

For optimal performance, make sure that the AxoSyslog source that feeds messages to this destination is configured properly: the value of the log-iw-size() option of the source must be higher than the batch-lines()*workers() of the destination. Otherwise, the size of the batches cannot reach the batch-lines() limit.

batch-timeout()


Type:	time in milliseconds
Default:	`-1` (disabled)

Description: Specifies the time AxoSyslog waits for lines to accumulate in the output buffer. The AxoSyslog application sends batches to the destinations evenly. The timer starts when the first message arrives to the buffer, so if only few messages arrive, AxoSyslog sends messages to the destination at most once every batch-timeout() milliseconds.

columns()


Type:	string list
Default:	“date”, “facility”, “level”, “host”, “program”, “pid”, “message”

Description: Name of the columns storing the data in fieldname [dbtype] format. The [dbtype] parameter is optional, and specifies the type of the field. By default, AxoSyslog creates text columns. Note that not every database engine can index text fields.

Warning The following column types cannot be used in MSSQL destinations: nchar, nvarchar, ntext, and xml.

create-statement-append()


Type:	string
Default:	empty string

Description: Specifies additional SQL options that are appended to the CREATE statement. That way you can customize what happens when AxoSyslog creates a new table in the database. Consult the documentation of your database server for details on the available options. Syntax:

   create-statement-append(<options-to-append>)

For example, you can appends the ROW_FORMAT=COMPRESSED option to MySQL create table statements:

   create-statement-append(ROW_FORMAT=COMPRESSED)

database()


Type:	string
Default:	logs

Description: Name of the database that stores the logs. Macros cannot be used in database name. Also, when using an Oracle database, you cannot use the same database() settings in more than one destination.

dbd-option()


Type:	string
Default:	empty string

Description: Specify database options that are set whenever AxoSyslog connects to the database server. Consult the documentation of your database server for details on the available options. Syntax:

   dbd-option(OPTION_NAME VALUE)

OPTION_NAME is always a string, VALUE is a string or a number. For example:

   dbd-option("null.sleep.connect" 1)
    dbd-option("null.sleep.query" 5)

dbdi-driver-dir()


Type:	string
Default:	empty string

Description: Defines an optional DBI driver location for DBD initialization.

disk-buffer()

Description: This option enables putting outgoing messages into the disk buffer of the destination to avoid message loss in case of a system failure on the destination side. It has the following options:

capacity-bytes()

Type:	number (bytes)
Default:	1MiB

Description: This is a required option. The maximum size of the disk-buffer in bytes. The minimum value is 1048576 bytes. If you set a smaller value, the minimum value will be used automatically. It replaces the old log-disk-fifo-size() option.

In AxoSyslog version 4.2 and earlier, this option was called disk-buf-size().

compaction()

Type:	yes/no
Default:	no

Description: If set to yes, AxoSyslog prunes the unused space in the LogMessage representation, making the disk queue size smaller at the cost of some CPU time. Setting the compaction() argument to yes is recommended when numerous name-value pairs are unset during processing, or when the same names are set multiple times.

Note Simply unsetting these name-value pairs by using the unset() rewrite operation is not enough, as due to performance reasons that help when AxoSyslog is CPU bound, the internal representation of a LogMessage will not release the memory associated with these name-value pairs. In some cases, however, the size of this overhead becomes significant (the raw message size can grow up to four times its original size), which unnecessarily increases the disk queue file size. For these cases, the compaction will drop unset values, making the LogMessage representation smaller at the cost of some CPU time required to perform compaction.

dir()

Type:	string
Default:	N/A

Description: Defines the folder where the disk-buffer files are stored.

Warning

When creating a new dir() option for a disk buffer, or modifying an existing one, make sure you delete the persist file.

AxoSyslog creates disk-buffer files based on the path recorded in the persist file. Therefore, if the persist file is not deleted after modifying the dir() option, then following a restart, AxoSyslog will look for or create disk-buffer files in their old location. To ensure that AxoSyslog uses the new dir() setting, the persist file must not contain any information about the destinations which the disk-buffer file in question belongs to.

Note If the dir() path provided by the user does not exist, AxoSyslog creates the path with the same permission as the running instance.

flow-control-window-bytes()

Type:	number (bytes)
Default:	163840000

Description: Use this option if the option reliable() is set to yes. This option contains the size of the messages in bytes that is used in the memory part of the disk buffer. It replaces the old log-fifo-size() option. It does not inherit the value of the global log-fifo-size() option, even if it is provided. Note that this option will be ignored if the option reliable() is set to no.

In AxoSyslog version 4.2 and earlier, this option was called mem-buf-size().

flow-control-window-size()

Type:	number(messages)
Default:	10000

Description: Use this option if the option reliable() is set to no. This option contains the number of messages stored in overflow queue. It replaces the old log-fifo-size() option. It inherits the value of the global log-fifo-size() option if provided. If it is not provided, the default value is 10000 messages. Note that this option will be ignored if the option reliable() is set to yes.

In AxoSyslog version 4.2 and earlier, this option was called mem-buf-length().

front-cache-size()

Type:	number(messages)
Default:	1000

Description: The number of messages stored in the output buffer of the destination. Note that if you change the value of this option and the disk-buffer already exists, the change will take effect when the disk-buffer becomes empty.

Options reliable() and capacity-bytes() are required options.

In AxoSyslog version 4.2 and earlier, this option was called qout-size().

prealloc()

Type:	yes/no
Default:	no

Description:

By default, AxoSyslog doesn’t reserve the disk space for the disk-buffer file, since in a properly configured and sized environment the disk-buffer is practically empty, so a large preallocated disk-buffer file is just a waste of disk space. But a preallocated buffer can prevent other data from using the intended buffer space (and elicit a warning from the OS if disk space is low), preventing message loss if the buffer is actually needed. To avoid this problem, when using AxoSyslog 4.0 or later, you can preallocate the space for your disk-buffer files by setting prealloc(yes).

In addition to making sure that the required disk space is available when needed, preallocated disk-buffer files provide radically better (3-4x) performance as well: in case of an outage the amount of messages stored in the disk-buffer is continuously growing, and using large continuous files is faster, than constantly waiting on a file to change its size.

If you are running AxoSyslog on a dedicated host (always recommended for any high-volume settings), use prealloc(yes).

Available in AxoSyslog 4.0 and later.

reliable()

Type:	yes/no
Default:	no

Description: If set to yes, AxoSyslog cannot lose logs in case of reload/restart, unreachable destination or AxoSyslog crash. This solution provides a slower, but reliable disk-buffer option. It is created and initialized at startup and gradually grows as new messages arrive. If set to no, the normal disk-buffer will be used. This provides a faster, but less reliable disk-buffer option.

Warning Hazard of data loss! If you change the value of reliable() option when there are messages in the disk-buffer, the messages stored in the disk-buffer will be lost.

truncate-size-ratio()

Type:	number((between 0 and 1))
Default:	1 (do not truncate)

Description: Limits the truncation of the disk-buffer file. Truncating the disk-buffer file can slow down the disk IO operations, but it saves disk space. By default, AxoSyslog version 4.0 and later doesn’t truncate disk-buffer files by default (truncate-size-ratio(1)). Earlier versions freed the disk-space when at least 10% of the disk-buffer file could be freed (truncate-size-ratio(0.1)).

AxoSyslog only truncates the file if the possible disk gain is more than truncate-size-ratio() times capacity-bytes().

Smaller values free disk space quicker.
Larger ratios result in better performance.

If you want to avoid performance fluctuations:

use truncate-size-ratio(1) (never truncate), or
use prealloc(yes) to reserve the entire size of the disk-buffer on disk.

Warning Axoflow does not recommend you to change truncate-size-ratio(). Only change its value if you understand the performance implications of doing so.

Example: Examples for using disk-buffer()

In the following case reliable disk-buffer() is used.

destination d_demo {
    network(
        "127.0.0.1"
        port(3333)
        disk-buffer(
            flow-control-window-bytes(10000)
            capacity-bytes(2000000)
            reliable(yes)
            dir("/tmp/disk-buffer")
        )
    );
};

In the following case normal disk-buffer() is used.

destination d_demo {
    network(
        "127.0.0.1"
        port(3333)
            disk-buffer(
            flow-control-window-size(10000)
            capacity-bytes(2000000)
            reliable(no)
            dir("/tmp/disk-buffer")
        )
    );
};

flags()


Type:	list of flags
Default:	empty string

Description: Flags related to the sql() destination.

dont-create-tables: Enable this flag to prevent AxoSyslog from creating non-existing database tables automatically. The AxoSyslog application typically has to create tables if you use macros in the table names. Available in AxoSyslog version 3.2 and later.
explicit-commits: By default, AxoSyslog commits every log message to the target database individually. When the explicit-commits option is enabled, messages are committed in batches. This improves the performance, but results in some latency, as the messages are not immediately sent to the database. The size and frequency of batched commits can be set using the batch-lines() parameter. The explicit-commits option is available in AxoSyslog version 3.2 and later.

Example: Setting flags for SQL destinations

The following example sets the dont-create-tables and explicit-commits flags for an sql() destination.

   flags(dont-create-tables,explicit-commits)

frac-digits()


Type:	number
Default:	0

Description: The AxoSyslog application can store fractions of a second in the timestamps according to the ISO8601 format. The frac-digits() parameter specifies the number of digits stored. The digits storing the fractions are padded by zeros if the original timestamp of the message specifies only seconds. Fractions can always be stored for the time the message was received.

Note The AxoSyslog application can add the fractions to non-ISO8601 timestamps as well.

Note As AxoSyslog is precise up to the microsecond, when the frac-digits() option is set to a value higher than 6, AxoSyslog will truncate the fraction seconds in the timestamps after 6 digits.

hook-commands()

Description: This option makes it possible to execute external programs when the relevant driver is initialized or torn down. The hook-commands() can be used with all source and destination drivers with the exception of the usertty() and internal() drivers.

Note The AxoSyslog application must be able to start and restart the external program, and have the necessary permissions to do so. For example, if your host is running AppArmor or SELinux, you might have to modify your AppArmor or SELinux configuration to enable AxoSyslog to execute external applications.

Using `hook-commands()` when AxoSyslog starts or stops

To execute an external program when AxoSyslog starts or stops, use the following options:

`startup()`

Type:	string
Default:	N/A

Description: Defines the external program that is executed as AxoSyslog starts.

`shutdown()`

Type:	string
Default:	N/A

Description: Defines the external program that is executed as AxoSyslog stops.

Using the hook-commands() when AxoSyslog reloads

To execute an external program when the AxoSyslog configuration is initiated or torn down, for example, on startup/shutdown or during a AxoSyslog reload, use the following options:

`setup()`

Type:	string
Default:	N/A

Description: Defines an external program that is executed when the AxoSyslog configuration is initiated, for example, on startup or during a AxoSyslog reload.

`teardown()`

Type:	string
Default:	N/A

Description: Defines an external program that is executed when the AxoSyslog configuration is stopped or torn down, for example, on shutdown or during a AxoSyslog reload.

Example: Using hook-commands() with a network source

In the following example, the hook-commands() is used with the network() driver and it opens an iptables port automatically as AxoSyslog is started/stopped.

The assumption in this example is that the LOGCHAIN chain is part of a larger ruleset that routes traffic to it. Whenever the AxoSyslog created rule is there, packets can flow, otherwise the port is closed.

source {
    network(transport(udp)
    hook-commands(
          startup("iptables -I LOGCHAIN 1 -p udp --dport 514 -j ACCEPT")
          shutdown("iptables -D LOGCHAIN 1")
        )
     );
};

host()


Type:	hostname or IP address
Default:	n/a

Description: Hostname of the database server. Note that Oracle destinations do not use this parameter, but retrieve the hostname from the /etc/tnsnames.ora file.

Note

If you specify host="localhost", AxoSyslog will use a socket to connect to the local database server. Use host="127.0.0.1" to force TCP communication between AxoSyslog and the local database server.

To specify the socket to use, set and export the MYSQL_UNIX_PORT environment variable, for example, MYSQL_UNIX_PORT=/var/lib/mysql/mysql.sock; export MYSQL_UNIX_PORT.

indexes()


Type:	string list
Default:	“date”, “facility”, “host”, “program”

Description: The list of columns that are indexed by the database to speed up searching. To disable indexing for the destination, include the empty indexes() parameter in the destination, simply omitting the indexes parameter will cause AxoSyslog to request indexing on the default columns.

The AxoSyslog application will create the name of indexes automaticaly with the following method:

In case of MsSQL, PostgreSQL, MySQL or SQLite or (Oracle but tablename < 30 characters): {table}_{column}_idx.
In case of Oracle and tablename > 30 characters: md5sum of {table}_{column}-1 and the first character will be replaced by “i” character and the md5sum will be truncated to 30 characters.

local-time-zone()


Type:	name of the timezone, or the timezone offset
Default:	The local timezone.

Description: Sets the timezone used when expanding filename and tablename templates.

The timezone can be specified by using the name, for example, time-zone("Europe/Budapest")), or as the timezone offset in +/-HH:MM format, for example, +01:00). On Linux and UNIX platforms, the valid timezone names are listed under the /usr/share/zoneinfo directory.

log-fifo-size()


Type:	number
Default:	Use global setting.

Description: The number of messages that the output queue can store.

null()


Type:	string
Default:

Description: If the content of a column matches the string specified in the null() parameter, the contents of the column will be replaced with an SQL NULL value. If unset (by default), the option does not match on any string. For details, see the Example: Using SQL NULL values.

Example: Using SQL NULL values

The null() parameter of the SQL driver can be used to replace the contents of a column with a special SQL NULL value. To replace every column that contains an empty string with NULL, use the null("") option, for example

   destination d_sql {
        sql(type(pgsql)
        host("logserver") username("syslog-ng") password("password")
        database("logs")
        table("messages_${HOST}_${R_YEAR}${R_MONTH}${R_DAY}")
        columns("datetime", "host", "program", "pid", "message")
        values("${R_DATE}", "${HOST}", "${PROGRAM}", "${PID}", "${MSGONLY}")
        indexes("datetime", "host", "program", "pid", "message")
        null(""));
    };

To replace only a specific column (for example, pid) if it is empty, assign a default value to the column, and use this default value in the null() parameter:

   destination d_sql {
        sql(type(pgsql)
        host("logserver") username("syslog-ng") password("password")
        database("logs")
        table("messages_${HOST}_${R_YEAR}${R_MONTH}${R_DAY}")
        columns("datetime", "host", "program", "pid", "message")
        values("${R_DATE}", "${HOST}", "${PROGRAM}", "${PID:-@@NULL@@}", "${MSGONLY}")
        indexes("datetime", "host", "program", "pid", "message")
        null("@@NULL@@"));
    };

Ensure that the default value you use does not appear in the actual log messages, because other occurrences of this string will be replaced with NULL as well.

password()


Type:	string
Default:	n/a

Description: Password of the database user.

port()


Type:	number
Default:	1433 TCP for MSSQL, 3306 TCP for MySQL, 1521 for Oracle, and 5432 TCP for PostgreSQL

Description: The port number to connect to.

quote-char()


Type:	string
Default:

Available in AxoSyslog version 4.3.0 and newer.

Description: Set custom quoting for table and index names (for example, MySQL needs sometimes this for certain identifiers).

Note: Using a backtick character needs special formatting, because AxoSyslog uses backticks for configuration parameter names. To use backticks as quote character, set a double backtick: quote-char("``")

retries()


Type:	number (insertion attempts)
Default:	3

Description: The number of insertion attempts. If AxoSyslog could not insert a message into the database, it will repeat the attempt until the number of attempts reaches retries, then drops the connection to the database. For example, AxoSyslog will try to insert a message maximum three times by default (once for first insertion and twice if the first insertion was failed).

session-statements()


Type:	comma-separated list of SQL statements
Default:	empty string

Description: Specifies one or more SQL-like statement which is executed after AxoSyslog has successfully connected to the database. For example:

   session-statements("SET COLLATION_CONNECTION='utf8_general_ci'")

Warning The AxoSyslog application does not validate or limit the contents of customized queries. Consequently, queries performed with a user with write-access can potentially modify or even harm the database. Use customized queries with care, and only for your own responsibility.

table()


Type:	string
Default:	messages

Description: Name of the database table to use (can include macros). When using macros, note that some databases limit the length of table names.

time-reopen()


Accepted values:	number [seconds]
Default:	60

Description: The time to wait in seconds before a dead connection is reestablished.

time-zone()


Type:	name of the timezone, or the timezone offset
Default:	unspecified

Description: Convert timestamps to the timezone specified by this option. If this option is not set, then the original timezone information in the message is used. Converting the timezone changes the values of all date-related macros derived from the timestamp, for example, HOUR. For the complete list of such macros, see Date-related macros.

type()


Type:	mssql, mysql, oracle, pgsql, or sqlite3
Default:	mysql

Description: Specifies the type of the database, that is, the DBI database driver to use. Use the mssql option to send logs to an MSSQL database. For details, see the examples of the databases on the following sections.

username()


Type:	string
Default:	n/a

Description: Name of the database user.

values()


Type:	string list
Default:	“${R_YEAR}-${R_MONTH}-${R_DAY}, ${R_HOUR}:${R_MIN}:${R_SEC}”, “${FACILITY}”, “${LEVEL}”, “${HOST}”, “${PROGRAM}”, “${PID}”, “${MSGONLY}”

Description: The parts of the message to store in the fields specified in the columns() parameter.

It is possible to give a special value calling: default (without quotation marks).It means that the value will be used that is the default of the column type of this value.

Example: Value: default

   columns("date datetime", "host varchar(32)", "row_id serial")
        values("${R_DATE}", "${HOST}", default)