![]() ![]() ![]() (Note that if there are any time-zone-dependent %-escapes, the computation is done in the zone specified by log_timezone.) The supported %-escapes are similar to those listed in the Open Group's strftime specification. The value is treated as a strftime pattern, so %-escapes can be used to specify time-varying file names. When logging_collector is enabled, this parameter sets the file names of the created log files. This parameter can only be set in the nf file or on the server command line. It can be specified as an absolute path, or relative to the cluster data directory. When logging_collector is enabled, this parameter determines the directory in which log files will be created. In contrast, syslog prefers to drop messages if it cannot write them, which means it may fail to log some messages in such cases but it will not block the rest of the system. This means that in case of extremely high load, server processes could be blocked while trying to send additional log messages when the collector has fallen behind. The logging collector is designed to never lose messages. (One common example is dynamic-linker failure messages another is error messages produced by scripts such as archive_command.) This parameter can only be set at server start. This approach is often more useful than logging to syslog, since some types of messages might not appear in syslog output. This parameter enables the logging collector, which is a background process that captures log messages sent to stderr and redirects them into log files. On Windows, when you use the eventlog option for log_destination, you should register an event source and its library with the operating system so that the Windows Event Viewer can display event log messages cleanly. To the syslog daemon's configuration file to make it work. PostgreSQL can log to syslog facilities LOCAL0 through LOCAL7 (see syslog_facility), but the default syslog configuration on most platforms will discard all such messages. On most Unix systems, you will need to alter the configuration of your system's syslog daemon in order to make use of the syslog option for log_destination. It is removed when none of stderr, csvlog or jsonlog are included in log_destination, and when the logging collector is disabled. Here is an example of this file's content:Ĭurrent_logfiles is recreated when a new log file is created as an effect of rotation, and when log_destination is reloaded. This provides a convenient way to find the logs currently in use by the instance. When either stderr, csvlog or jsonlog are included, the file current_logfiles is created to record the location of the log file(s) currently in use by the logging collector and the associated logging destination. logging_collector must be enabled to generate JSON-format log output. If jsonlog is included in log_destination, log entries are output in JSON format, which is convenient for loading logs into programs. ![]() logging_collector must be enabled to generate CSV-format log output. If csvlog is included in log_destination, log entries are output in “ comma separated value” ( CSV) format, which is convenient for loading logs into programs. Set this parameter to a list of desired log destinations separated by commas. That may take a long time if your system suddenly becomes less active.PostgreSQL supports several methods for logging server messages, including stderr, csvlog, jsonlog, and syslog. This saves the disk some I/O, especially on busy systems.īear in mind that once a particular file has been recycled, it will not be reconsidered for removal/recycle again until it has been used (i.e., the relevant LSN is reached and checkpointed). So, as per your observation, you are probably observing the "recycle" effect - the old WAL files are getting renamed instead of getting removed. Below that limit, the system recycles enough WAL files to cover the estimated need until the next checkpoint, and removes the rest If, due to a short-term peak of log output rate, max_wal_size is exceeded, the unneeded segment files will be removed until the system gets back under this limit. When old log segment files are no longer needed, they are removed or recycled (that is, renamed to become future segments in the numbered sequence). The number of WAL segment files in pg_xlog directory depends on min_wal_size, max_wal_size and the amount of WAL generated in previous checkpoint cycles. As per the documentation (emphasis added): ![]()
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