How to diagnose and fix the 53200 out_of_memory error code in Postgres.

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The 53200 error code in PostgreSQL indicates an out_of_memory condition. This error occurs when PostgreSQL cannot allocate enough memory for a query to run. This could be due to insufficient system memory, overly aggressive memory settings for PostgreSQL parameters, or queries that require more memory than is available.

Diagnosis:

  1. Check the PostgreSQL server logs for any additional context around the out_of_memory error.
  2. Review the query that caused the error to see if it’s unusually complex or involves large datasets.
  3. Examine PostgreSQL memory configuration parameters such as work_mem, shared_buffers, maintenance_work_mem, and max_connections to ensure they are set appropriately for your system’s resources.
  4. Monitor system resources to see if there is enough free memory available and to identify any other processes that may be consuming excessive memory.

Fix:

Depending on the diagnosis, there are several ways to fix an out_of_memory error:

Example 1: Adjust memory configuration parameters

If the memory settings in PostgreSQL are too high for the available system memory, you can adjust them to more conservative values.

-- Reduce work_mem if it's set too high
ALTER SYSTEM SET work_mem = '64MB'; -- Adjust the size to fit your system

-- Reduce max_connections if it's set too high
ALTER SYSTEM SET max_connections = 100; -- Adjust the number to fit your system

-- Don't forget to reload the configuration for changes to take effect
SELECT pg_reload_conf();

Example 2: Optimize the query

If a specific query is causing the issue, try to optimize it by breaking it into smaller parts, using temporary tables, or improving the use of indexes.

-- Instead of a single complex query, break it down into smaller steps
BEGIN;
CREATE TEMP TABLE temp_result AS
SELECT * FROM large_table WHERE complex_condition;

-- Create an index on the temporary table if necessary
CREATE INDEX ON temp_result (column_used_in_next_query);

-- Use the temporary table in subsequent queries
SELECT * FROM temp_result WHERE additional_condition;
COMMIT;

Example 3: Increase system resources

If your PostgreSQL instance is consistently running out of memory, you may need to add more RAM to your server.

Example 4: Use resource limits

For environments that support it, such as cloud-based instances, you can set resource limits to prevent PostgreSQL from using all available memory.

-- Set a limit on memory PostgreSQL can use (example for a Linux-based system)
ulimit -Sv 2097152 # Set the virtual memory limit to 2GB

Example 5: Review and reduce memory-intensive operations

Examine your queries and configurations to identify operations that consume a lot of memory, such as large sorts or hash tables, and find ways to make them less memory-intensive.

Considerations:

  • Always test configuration changes in a development or staging environment before applying them to production.
  • Be cautious when adjusting memory parameters; setting them too high or too low can negatively impact performance.
  • Make sure your database statistics are up to date with ANALYZE, as outdated statistics can lead to inefficient query plans.
  • Consider using EXPLAIN to analyze the query execution plan and identify potential areas for optimization.
  • Regularly monitor your system’s memory usage to proactively manage resources and avoid out_of_memory errors.

By following these steps and making the necessary adjustments based on your specific situation, you can fix the 53200 out_of_memory error code in PostgreSQL. For more information on PostgreSQL memory management, you can refer to the PostgreSQL documentation on managing memory.

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