Error
Error Code:
53400
PostgreSQL Error 53400: Configuration Limit Exceeded
Description
This error indicates that PostgreSQL has reached a configured resource limit, preventing it from performing further operations or allocating necessary resources. It typically occurs when the database system or underlying operating system runs out of a specific resource or hits a predefined threshold.
Error Message
configuration limit exceeded
Known Causes
4 known causesMaximum Connections Reached
The `max_connections` parameter is set too low, and the database has received more concurrent client connections than it can handle.
Shared Buffer Exhaustion
The `shared_buffers` parameter is configured too low, leading to insufficient memory for caching data pages, especially under heavy read/write workloads.
Work Memory Inadequacy
Complex queries requiring large sorts or hash tables exceed the `work_mem` setting, causing them to spill to disk or fail due to resource constraints.
OS Resource Constraints
The underlying operating system has reached its own limits for open files, processes, or available memory, impacting PostgreSQL's ability to operate.
Solutions
3 solutions available1. Increase Max Connections easy
Temporarily increase the maximum number of allowed client connections.
1
Connect to your PostgreSQL server using a superuser role (e.g., 'postgres').
2
Edit the PostgreSQL configuration file (postgresql.conf). The location varies by OS and installation method. Common locations include `/etc/postgresql/<version>/main/postgresql.conf` on Debian/Ubuntu or within the PostgreSQL data directory on other systems.
3
Locate the `max_connections` parameter. If it's commented out (starts with '#'), uncomment it.
#max_connections = 1004
Increase the value of `max_connections`. A common starting point is to double the current value or set it to a value that accommodates your expected peak load. Be mindful that each connection consumes memory.
max_connections = 2005
Save the `postgresql.conf` file.
6
Restart the PostgreSQL service for the changes to take effect.
sudo systemctl restart postgresql2. Identify and Terminate Idle Connections medium
Find and close unnecessary, idle client connections that are consuming resources.
1
Connect to your PostgreSQL server using a superuser role.
2
Query the `pg_stat_activity` view to identify active connections and their states. Look for connections with a `state` of 'idle' or 'idle in transaction'.
SELECT pid, datname, usename, client_addr, state, query_start, state_change FROM pg_stat_activity WHERE state = 'idle' OR state = 'idle in transaction';3
For identified idle connections, determine if they can be safely terminated. Consider the application that owns the connection and if terminating it will cause issues.
4
If a connection can be terminated, use the `pg_terminate_backend()` function with the `pid` obtained from the previous query. Be cautious when using this function as it abruptly closes the connection.
SELECT pg_terminate_backend(<pid_of_idle_connection>);5
Re-run the query from step 2 to confirm that the connection has been terminated.
3. Implement Connection Pooling advanced
Use a connection pooler to manage and reuse database connections efficiently.
1
Choose a connection pooler. Popular options include PgBouncer and Odyssey.
2
Install the chosen connection pooler on a server accessible to your PostgreSQL instance. This can be the same server or a separate one.
3
Configure the connection pooler. This typically involves defining the PostgreSQL server address, port, user, and password, as well as the pooling mode (e.g., 'session', 'transaction', 'statement').
4
Update your application's database connection strings to point to the connection pooler's address and port instead of directly to PostgreSQL.
5
Start the connection pooler service.
6
Monitor the connection pooler's statistics to ensure it's effectively managing connections and that the `max_connections` in PostgreSQL is no longer being hit.