Where postgresql store logs – quick start 2024-25

Understanding PostgreSQL Log Files: Where Information Resides & Where postgresql store logs

Where postgresql store logs – PostgreSQL, a powerful open-source relational database management system, maintains a detailed record of its activities through log files. These logs are invaluable for troubleshooting, performance tuning, and ensuring the overall health of the database. In this article, we’ll explore where PostgreSQL store logs and how you can leverage this information.

Where postgresql store logs

PostgreSQL Log File Locations: Where postgresql store logs

PostgreSQL logs are typically stored in the “pg_log” directory within the PostgreSQL data directory. The exact location may vary based on your operating system and PostgreSQL version.

On Linux/Unix Systems

On Linux/Unix systems, PostgreSQL log files are commonly found in the “data” directory under the PostgreSQL installation path. The path may look something like this


On Windows Systems

On Windows systems, the log files are often located within the PostgreSQL data directory. The path may resemble the following:

C:\Program Files\PostgreSQL\{version}\data\pg_log\

Log File Naming Convention

PostgreSQL log files are typically named using a convention that includes the server’s hostname, the PostgreSQL service name, and the log start timestamp. For example


Here, SERVERNAME is the hostname of the server running PostgreSQL.

Configuring PostgreSQL Logging

To effectively manage PostgreSQL logs, you may need to configure the logging settings. The configuration file for PostgreSQL, postgresql.conf, contains parameters related to logging. Common parameters include:

  • log_destination: Specifies where to send log output. Options include stderr, csvlog (CSV format), syslog, and more.
  • logging_collector: Enables or disables the background process responsible for collecting log files.
  • log_directory: Specifies the directory where log files are stored.
  • log_filename: Specifies the prefix of the log file names.
  • log_statement: Controls which SQL statements are logged. Options include none, ddl, mod, all, etc.

To make changes to the logging configuration, edit the postgresql.conf file and restart the PostgreSQL server for the changes to take effect.

Analyzing PostgreSQL Logs

Once you’ve located the PostgreSQL log files, you can analyze them using various tools. Here are some common approaches

Manual Inspection

Open the log files using a text editor to manually inspect the entries. Look for messages related to errors, warnings, or performance issues.


Use tools like pgBadger to parse and analyze PostgreSQL log files, generating detailed reports and visualizations.

Query Log Tables

PostgreSQL provides system views like pg_stat_statements and pg_stat_bgwriter that can be queried to gather insights into database performance.

Tail Command

Use the tail command in a terminal to monitor log entries in real-time. For example:

tail -f /var/lib/pgsql/{version}/data/pg_log/postgresql-SERVERNAME.log

How to analyze postgresql logs?

Analyzing PostgreSQL Logs: Unveiling Insights for Database Health

PostgreSQL, a robust open-source relational database management system, generates logs that are a goldmine of information for database administrators. Analyzing these logs is a crucial aspect of database maintenance, providing insights into performance, errors, and potential issues. In this article, we’ll explore how to effectively analyze PostgreSQL logs to unveil valuable information about the health of your database.

PostgreSQL Log Types

PostgreSQL produces different types of logs, each serving a specific purpose. Understanding these log types is essential for targeted analysis.

Error Logs (postgresql.log)

These logs capture error messages, warnings, and critical issues encountered by the PostgreSQL server.

Query Logs (postgresql.log or csvlog)

Query logs provide details about SQL queries executed on the database, aiding in performance tuning and optimization.

Connection Logs (postgresql.log)

Connection logs record information about client connections, disconnections, and authentication attempts.

Steps to Analyze PostgreSQL Logs

Locate the Log Files

  • Determine the location of your PostgreSQL log files. Common locations include:
  • On Linux/Unix: /var/lib/pgsql/{version}/data/pg_log/
    • On Windows: C:\Program Files\PostgreSQL\{version}\data\pg_log\

Use Tail or Cat Commands

For real-time monitoring, use the tail command on Linux/Unix or the Get-Content command on PowerShell for Windows. Example:

Bash Command –
tail -f /var/lib/pgsql/{version}/data/pg_log/postgresql.log

Powershell command-
Get-Content "C:\Program Files\PostgreSQL\{version}\data\pg_log\postgresql.log" –Wait

Filter Logs by Severity

PostgreSQL logs include severity levels such as INFO, WARNING, ERROR, etc. Filter logs based on severity to focus on specific issues.

SQL command –
SELECT * FROM pg_read_file('pg_log/postgresql.log') WHERE log_severity = 'ERROR';

Check for Performance Insights

Look for entries related to query performance, long-running queries, or queries requiring optimization. Use the pg_stat_statements view for detailed query statistics.

SQL Command –
SELECT * FROM pg_stat_statements ORDER BY total_time DESC LIMIT 10;

Identify Connection Issues

Analyze connection logs to identify issues such as failed authentication attempts or unexpected disconnections.

SQL Command -
SELECT * FROM pg_read_file('pg_log/postgresql.log') WHERE log_type = 'FATAL';

Use pgBadger for Detailed Reports

Consider using tools like pgBadger, a PostgreSQL log analyzer, to generate detailed reports and visualizations.

Bash Command-
pgbadger /var/lib/pgsql/{version}/data/pg_log/postgresql.log

Query Log Tables

PostgreSQL provides system views like pg_stat_statements and pg_stat_bgwriter that can be queried to gather insights into database performance.

SQL Command -
SELECT * FROM pg_stat_statements ORDER BY total_time DESC LIMIT 10;

To learn about, quick start Connect to azure postgres database using pgadmin 4, click here.

Leave a Comment