application_name (string) #
The application_name can be any string of less than NAMEDATALEN characters (64 characters in a standard build). It is typically set by an application upon connection to the server. The name will be displayed in the pg_stat_activity view and included in CSV log entries. It can also be included in regular log entries via the log_line_prefix parameter. Only printable ASCII characters may be used in the application_name value. Other characters are replaced with C-style hexadecimal escapes.
debug_print_parse (boolean) debug_print_rewritten (boolean) debug_print_plan (boolean) #
These parameters enable various debugging output to be emitted. When set, they print the resulting parse tree, the query rewriter output, or the execution plan for each executed query. These messages are emitted at LOG message level, so by default they will appear in the server log but will not be sent to the client. You can change that by adjusting client_min_messages and/or log_min_messages. These parameters are off by default.
debug_pretty_print (boolean) #
When set, debug_pretty_print indents the messages produced by debug_print_parse, debug_print_rewritten, or debug_print_plan. This results in more readable but much longer output than the “compact” format used when it is off. It is on by default.
log_autovacuum_min_duration (integer) #
Causes each action executed by autovacuum to be logged if it ran for at least the specified amount of time. Setting this to zero logs all autovacuum actions. -1 disables logging autovacuum actions. If this value is specified without units, it is taken as milliseconds. For example, if you set this to 250ms then all automatic vacuums and analyzes that run 250ms or longer will be logged. In addition, when this parameter is set to any value other than -1, a message will be logged if an autovacuum action is skipped due to a conflicting lock or a concurrently dropped relation. The default is 10min. Enabling this parameter can be helpful in tracking autovacuum activity. This parameter can only be set in the postgresql.conf file or on the server command line; but the setting can be overridden for individual tables by changing table storage parameters.
log_checkpoints (boolean) #
Causes checkpoints and restartpoints to be logged in the server log. Some statistics are included in the log messages, including the number of buffers written and the time spent writing them. This parameter can only be set in the postgresql.conf file or on the server command line. The default is on.
log_connections (string) #
Causes aspects of each connection to the server to be logged. The default is the empty string, '', which disables all connection logging. The following options may be specified alone or in a comma-separated list:
Table 19.3. Log Connection Options
Name Descriptionreceipt Logs receipt of a connection. authentication Logs the original identity used by an authentication method to identify a user. In most cases, the identity string matches the PostgreSQL username, but some third-party authentication methods may alter the original user identifier before the server stores it. Failed authentication is always logged regardless of the value of this setting. authorization Logs successful completion of authorization. At this point the connection has been established but the backend is not yet fully set up. The log message includes the authorized username as well as the database name and application name, if applicable. setup_durations Logs the time spent establishing the connection and setting up the backend until the connection is ready to execute its first query. The log message includes three durations: the total setup duration (starting from the postmaster accepting the incoming connection and ending when the connection is ready for query), the time it took to fork the new backend, and the time it took to authenticate the user. all A convenience alias equivalent to specifying all options. If all is specified in a list of other options, all connection aspects will be logged.
Disconnection logging is separately controlled by log_disconnections.
For the purposes of backwards compatibility, on, off, true, false, yes, no, 1, and 0 are still supported. The positive values are equivalent to specifying the receipt, authentication, and authorization options.
Only superusers and users with the appropriate SET privilege can change this parameter at session start, and it cannot be changed at all within a session.
Some client programs, like psql, attempt to connect twice while determining if a password is required, so duplicate “connection received” messages do not necessarily indicate a problem.
log_disconnections (boolean) #
Causes session terminations to be logged. The log output provides information similar to log_connections, plus the duration of the session. Only superusers and users with the appropriate SET privilege can change this parameter at session start, and it cannot be changed at all within a session. The default is off.
log_duration (boolean) #
Causes the duration of every completed statement to be logged. The default is off. Only superusers and users with the appropriate SET privilege can change this setting.
For clients using extended query protocol, durations of the Parse, Bind, and Execute steps are logged independently.
NoteThe difference between enabling log_duration and setting log_min_duration_statement to zero is that exceeding log_min_duration_statement forces the text of the query to be logged, but this option doesn't. Thus, if log_duration is on and log_min_duration_statement has a positive value, all durations are logged but the query text is included only for statements exceeding the threshold. This behavior can be useful for gathering statistics in high-load installations.
log_error_verbosity (enum) #
Controls the amount of detail written in the server log for each message that is logged. Valid values are TERSE, DEFAULT, and VERBOSE, each adding more fields to displayed messages. TERSE excludes the logging of DETAIL, HINT, QUERY, and CONTEXT error information. VERBOSE output includes the SQLSTATE error code (see also Appendix A) and the source code file name, function name, and line number that generated the error. Only superusers and users with the appropriate SET privilege can change this setting.
log_hostname (boolean) #
By default, connection log messages only show the IP address of the connecting host. Turning this parameter on causes logging of the host name as well. Note that depending on your host name resolution setup this might impose a non-negligible performance penalty. This parameter can only be set in the postgresql.conf file or on the server command line.
log_line_prefix (string) #
This is a printf-style string that is output at the beginning of each log line. % characters begin “escape sequences” that are replaced with status information as outlined below. Unrecognized escapes are ignored. Other characters are copied straight to the log line. Some escapes are only recognized by session processes, and will be treated as empty by background processes such as the main server process. Status information may be aligned either left or right by specifying a numeric literal after the % and before the option. A negative value will cause the status information to be padded on the right with spaces to give it a minimum width, whereas a positive value will pad on the left. Padding can be useful to aid human readability in log files.
This parameter can only be set in the postgresql.conf file or on the server command line. The default is '%m [%p] ' which logs a time stamp and the process ID.
%a Application name yes %u User name yes %d Database name yes %r Remote host name or IP address, and remote port yes %h Remote host name or IP address yes %L Local address (the IP address on the server that the client connected to) yes %b Backend type no %p Process ID no %P Process ID of the parallel group leader, if this process is a parallel query worker no %t Time stamp without milliseconds no %m Time stamp with milliseconds no %n Time stamp with milliseconds (as a Unix epoch) no %i Command tag: type of session's current command yes %e SQLSTATE error code no %c Session ID: see below no %l Number of the log line for each session or process, starting at 1 no %s Process start time stamp no %v Virtual transaction ID (procNumber/localXID); see Section 67.1 no %x Transaction ID (0 if none is assigned); see Section 67.1 no %q Produces no output, but tells non-session processes to stop at this point in the string; ignored by session processes no %Q Query identifier of the current query. Query identifiers are not computed by default, so this field will be zero unless compute_query_id parameter is enabled or a third-party module that computes query identifiers is configured. yes %% Literal % no
The backend type corresponds to the column backend_type in the view pg_stat_activity, but additional types can appear in the log that don't show in that view.
The %c escape prints a quasi-unique session identifier, consisting of two 4-byte hexadecimal numbers (without leading zeros) separated by a dot. The numbers are the process start time and the process ID, so %c can also be used as a space saving way of printing those items. For example, to generate the session identifier from pg_stat_activity, use this query:
SELECT to_hex(trunc(EXTRACT(EPOCH FROM backend_start))::integer) || '.' ||
to_hex(pid)
FROM pg_stat_activity;
Tip
If you set a nonempty value for log_line_prefix, you should usually make its last character be a space, to provide visual separation from the rest of the log line. A punctuation character can be used too.
Syslog produces its own time stamp and process ID information, so you probably do not want to include those escapes if you are logging to syslog.
TipThe %q escape is useful when including information that is only available in session (backend) context like user or database name. For example:
log_line_prefix = '%m [%p] %q%u@%d/%a 'Note
The %Q escape always reports a zero identifier for lines output by log_statement because log_statement generates output before an identifier can be calculated, including invalid statements for which an identifier cannot be calculated.
log_lock_waits (boolean) #
Controls whether a log message is produced when a session waits longer than deadlock_timeout to acquire a lock. This is useful in determining if lock waits are causing poor performance. The default is off. Only superusers and users with the appropriate SET privilege can change this setting.
log_lock_failures (boolean) #
Controls whether a detailed log message is produced when a lock acquisition fails. This is useful for analyzing the causes of lock failures. Currently, only lock failures due to SELECT NOWAIT is supported. The default is off. Only superusers and users with the appropriate SET privilege can change this setting.
log_recovery_conflict_waits (boolean) #
Controls whether a log message is produced when the startup process waits longer than deadlock_timeout for recovery conflicts. This is useful in determining if recovery conflicts prevent the recovery from applying WAL.
The default is off. This parameter can only be set in the postgresql.conf file or on the server command line.
log_parameter_max_length (integer) #
If greater than zero, each bind parameter value logged with a non-error statement-logging message is trimmed to this many bytes. Zero disables logging of bind parameters for non-error statement logs. -1 (the default) allows bind parameters to be logged in full. If this value is specified without units, it is taken as bytes. Only superusers and users with the appropriate SET privilege can change this setting.
This setting only affects log messages printed as a result of log_statement, log_duration, and related settings. Non-zero values of this setting add some overhead, particularly if parameters are sent in binary form, since then conversion to text is required.
log_parameter_max_length_on_error (integer) #
If greater than zero, each bind parameter value reported in error messages is trimmed to this many bytes. Zero (the default) disables including bind parameters in error messages. -1 allows bind parameters to be printed in full. If this value is specified without units, it is taken as bytes.
Non-zero values of this setting add overhead, as PostgreSQL will need to store textual representations of parameter values in memory at the start of each statement, whether or not an error eventually occurs. The overhead is greater when bind parameters are sent in binary form than when they are sent as text, since the former case requires data conversion while the latter only requires copying the string.
log_statement (enum) #
Controls which SQL statements are logged. Valid values are none (off), ddl, mod, and all (all statements). ddl logs all data definition statements, such as CREATE, ALTER, and DROP statements. mod logs all ddl statements, plus data-modifying statements such as INSERT, UPDATE, DELETE, TRUNCATE, and COPY FROM. PREPARE, EXECUTE, and EXPLAIN ANALYZE statements are also logged if their contained command is of an appropriate type. For clients using extended query protocol, logging occurs when an Execute message is received, and values of the Bind parameters are included (with any embedded single-quote marks doubled).
The default is none. Only superusers and users with the appropriate SET privilege can change this setting.
Statements that contain simple syntax errors are not logged even by the log_statement = all setting, because the log message is emitted only after basic parsing has been done to determine the statement type. In the case of extended query protocol, this setting likewise does not log statements that fail before the Execute phase (i.e., during parse analysis or planning). Set log_min_error_statement to ERROR (or lower) to log such statements.
Logged statements might reveal sensitive data and even contain plaintext passwords.
log_replication_commands (boolean) #
Causes each replication command and walsender process's replication slot acquisition/release to be logged in the server log. See Section 54.4 for more information about replication command. The default value is off. Only superusers and users with the appropriate SET privilege can change this setting.
log_temp_files (integer) #
Controls logging of temporary file names and sizes. Temporary files can be created for sorts, hashes, and temporary query results. If enabled by this setting, a log entry is emitted for each temporary file, with the file size specified in bytes, when it is deleted. A value of zero logs all temporary file information, while positive values log only files whose size is greater than or equal to the specified amount of data. If this value is specified without units, it is taken as kilobytes. The default setting is -1, which disables such logging. Only superusers and users with the appropriate SET privilege can change this setting.
log_timezone (string) #
Sets the time zone used for timestamps written in the server log. Unlike TimeZone, this value is cluster-wide, so that all sessions will report timestamps consistently. The built-in default is GMT, but that is typically overridden in postgresql.conf; initdb will install a setting there corresponding to its system environment. See Section 8.5.3 for more information. This parameter can only be set in the postgresql.conf file or on the server command line.
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