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.
[MyLogFilter]
type=filter
module=qlafilter
[MyService]
type=service
router=readconnroute
servers=server1
user=myuser
password=mypasswd
filters=MyLogFilter
The QLA filter accepts the following options.
| Option | Description |
|---|---|
| ignorecase | Use case-insensitive matching |
| case | Use case-sensitive matching |
| extended | Use extended regular expression syntax (ERE) |
To use multiple filter options, list them in a comma-separated list. If no options are given, default will be used. Multiple options can be enabled simultaneously.
options=case,extended
Note: older the version of the QLA filter in 0.7 of MariaDB MaxScale used
the options to define the location of the log files. This functionality is not
supported anymore and the filebase parameter should be used instead.
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.
filebase=/tmp/SqlQueryLog
The filebase may also be set as the filter option. If both option and parameter are set, the parameter setting will be used and the filter option ignored.
These optional parameters limit logging on a query level. The parameter values are regular expressions which are matched against the SQL query text. Only SQL statements that match the regular expression in match but do not match the exclude expression are logged.
match=select.*from.*customer.*where
exclude=^insert
match is checked before exclude. If match is empty, all queries are considered matching. If exclude is empty, no query is exluded. If both are empty, all queries are logged.
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.
user=john
source=127.0.0.1
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 |
log_type=session
If both logs are required, define log_type=session,unified.
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 | Response time (ms until first reply from server) |
| query | Query |
log_data=date, user, query
If reply_time is enabled, the log entry is written when the first reply from server is received. Otherwise, the entry is written when receiving query from client.
Flush log files after every write. The default is false.
flush=true
Append new entries to log files instead of overwriting them. The default is false.
append=true
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 "
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:
[ProductsSelectLogger]
type=filter
module=qlafilter
match=SELECT.*from.*PRODUCTS .*
exclude=WHERE.*PRODUCT_ID.*
filebase=/var/logs/qla/SelectProducts
[Product-Service]
type=service
router=readconnrouter
servers=server1
user=myuser
password=mypasswd
filters=ProductsSelectLogger
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