Query Log All Filter

Query Log All Filter


The Query Log All (QLA) filter logs query content. Logs are written to a file in CSV format. Log elements are configurable and include the time submitted and the SQL statement text, among others.


A minimal configuration is below.



Log Rotation

The qlafilter logs can be rotated by executing the maxctrl rotate logs command. This will cause the log files to be reopened when the next message is written to the file. This applies to both unified and session type logging.

Filter Parameters

The QLA filter has one mandatory parameter, filebase, and a number of optional parameters. These were introduced in the 1.0 release of MariaDB MaxScale.


The basename of the output file created for each session. A session index is added to the filename for each written session file. For unified log files, .unified is appended. This is a mandatory parameter.


match, exclude and options

These regular expression settings limit which queries are logged.


user and source

These optional parameters limit logging on a session level. If user is defined, only the sessions with a matching client username are logged. If source is defined, only sessions with a matching client source address are logged.



The type of log file to use. The default value is session.

Value Description
session Write to session-specific files
unified Use one file for all sessions
stdout Same as unified, but to stdout

The log types can be combined, e.g. setting log_type=session,stdout will write both session-specific files, and all sessions to stdout.


Type of data to log in the log files. The parameter value is a comma separated list of the following elements. By default the date, user and query options are enabled.

Value Description
service Service name
session Unique session id (ignored for session files)
date Timestamp
user User and hostname of client
reply_time Duration from client query to first server reply
total_reply_time Duration from client query to last server reply (v6.2)
query Query
default_db The default (current) database
num_rows Number of rows in the result set (v6.2)
reply_size Number of bytes received from the server (v6.2)
transaction BEGIN, COMMIT and ROLLBACK (v6.2)
transaction_time The duration of a transaction (v6.2)
num_warnings Number of warnings in the server reply (v6.2)
error_msg Error message from the server (if any) (v6.2)
server The server where the query was routed (if any) (v22.08)
log_data=date, user, query, total_reply_time

The durations reply_time and total_reply_time are by default in milliseconds, but can be specified to be in microseconds using duration_unit.

The log entry is written when the last reply from the server is received. Prior to version 6.2 the entry was written when the query was received from the client, or if reply_time was specified, on first reply from the server.

NOTE The error_msg is the raw message from the server. Even if use_canonical_form is set the error message may contain user defined constants. For example:

MariaDB [test]> select secret from T where x password="clear text pwd";
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual
that corresponds to your MariaDB server version for the right syntax to
use near 'password="clear text pwd"' at line 1


The unit for logging a duration. The unit can be milliseconds or microseconds. The abbreviations ms for milliseconds and us for microseconds are also valid. The default is milliseconds. This option is available as of MaxScale version 6.2.



When this option is true the canonical form of the query is logged. In the canonical form all user defined constants are replaced with question marks. The default is false, i.e. log the sql as is. This option is available as of MaxScale version 6.2.



Flush log files after every write. The default is false.



Append new entries to log files instead of overwriting them. The default is true. NOTE: the default was changed from false to true, as of the following versions: 2.4.18, 2.5.16 and 6.2.



Default value is "," (a comma). Defines the separator string between elements of a log entry. The value should be enclosed in quotes.

separator=" | "


Default value is " " (one space). SQL-queries may include line breaks, which, if printed directly to the log, may break automatic parsing. This parameter defines what should be written in the place of a newline sequence (\r, \n or \r\n). If this is set as the empty string, then newlines are not replaced and printed as is to the output. The value should be enclosed in quotes.

newline_replacement=" NL "


Example 1 - Query without primary key

Imagine you have observed an issue with a particular table and you want to determine if there are queries that are accessing that table but not using the primary key of the table. Let's assume the table name is PRODUCTS and the primary key is called PRODUCT_ID. Add a filter with the following definition:

match=SELECT.*from.*PRODUCTS .*


The result of using this filter with the service used by the application would be a log file of all select queries querying PRODUCTS without using the PRODUCT_ID primary key in the predicates of the query. Executing SELECT * FROM PRODUCTS would log the following into /var/logs/qla/SelectProducts:

07:12:56.324 7/01/2016, SELECT * FROM PRODUCTS


Comments loading...
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.