How to diagnose and fix the 53400 configuration_limit_exceeded error code in Postgres.

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The 53400 error code in PostgreSQL indicates a “configuration_limit_exceeded” error. This error occurs when a database configuration parameter that has a defined limit is exceeded. Common situations that can trigger this error include exceeding the maximum number of allowed connections, running out of available locks, or exceeding other resource-related configuration limits.

To diagnose and fix this error, you’ll need to identify which configuration limit has been exceeded and then take appropriate action to resolve the issue. Here are some scenarios where this error might occur, along with examples and potential fixes:

Scenario 1: Maximum Number of Connections Exceeded

If you exceed the maximum number of database connections specified by the max_connections setting, you’ll encounter this error.

Example:

-- Error occurs when trying to establish a new connection if the max_connections limit is reached.

Fix:
You can either increase the max_connections setting or use connection pooling to manage connections more efficiently.

To increase max_connections:

-- Modify postgresql.conf file and increase the max_connections setting.
-- For example, change it to 200 if the current limit is 100:
max_connections = 200

-- Then, restart the PostgreSQL server to apply the changes.

To implement connection pooling, you can use tools like PgBouncer or Pgpool.

Scenario 2: Running Out of Locks

PostgreSQL has a configuration parameter max_locks_per_transaction that defines the maximum number of locks each transaction can hold. Exceeding this limit can cause the 53400 error.

Example:

-- Error occurs when a transaction tries to acquire more locks than max_locks_per_transaction allows.

Fix:
Increase the max_locks_per_transaction setting in the postgresql.conf file.

To increase max_locks_per_transaction:

-- Modify postgresql.conf file and increase the max_locks_per_transaction setting.
-- For example, change it to 128 if the current limit is 64:
max_locks_per_transaction = 128

-- You may also need to increase max_locks_per_transaction for shared locks:
max_locks_per_transaction * (max_connections + max_prepared_transactions)

-- Then, restart the PostgreSQL server to apply the changes.

Scenario 3: Shared Memory Limits

PostgreSQL uses shared memory for various operations, and if the limits are exceeded, it can trigger the 53400 error.

Example:

-- Error occurs when shared memory usage exceeds the system's configuration limits.

Fix:
You may need to increase the shared memory-related parameters in the postgresql.conf file, such as shared_buffers, and also adjust the operating system’s shared memory settings.

To increase shared_buffers:

-- Modify postgresql.conf file and increase the shared_buffers setting.
-- For example, change it to 4GB if the current limit is 2GB:
shared_buffers = 4GB

-- Adjust the operating system's shared memory settings if necessary.

-- Then, restart the PostgreSQL server to apply the changes.

General Tips for Diagnosis and Fixes:

  1. Review Error Logs:
    Check the PostgreSQL error logs to identify which configuration limit was exceeded.
  2. Understand Configuration Parameters:
    Familiarize yourself with PostgreSQL configuration parameters that have limits and understand their impact on database performance.
  3. Monitor Resources:
    Use monitoring tools to keep an eye on database resource usage and identify potential issues before they lead to errors.
  4. Adjust Configuration:
    When necessary, adjust the relevant configuration parameters in the postgresql.conf file and restart the PostgreSQL server to apply changes.
  5. Consider System Resources:
    Ensure that the system has sufficient resources (CPU, memory, etc.) to handle the new configuration limits.
  6. Optimize Application:
    Review the application’s database usage patterns and optimize queries, transactions, and connection handling to reduce resource consumption.

By carefully monitoring resource usage and understanding PostgreSQL’s configuration parameters, you can effectively diagnose and resolve the 53400 configuration_limit_exceeded error. For more detailed information on configuration settings, consult the PostgreSQL documentation.

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