How to diagnose and fix the 55006 object_in_use error code in Postgres.

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The 55006 error code in PostgreSQL indicates an object_in_use situation. This error occurs when you attempt to perform an operation on a database object that is currently being accessed by another session or user. Common scenarios include trying to drop a database or table that is in use, or altering an object that is being accessed.

Diagnosis:

  1. Identify the object that is causing the error from the error message.
  2. Check if there are active connections or transactions using the object. You can query the pg_stat_activity view to see active connections:
SELECT * FROM pg_stat_activity WHERE datname = 'your_database_name';
  1. Determine if there are any background processes like autovacuum that might be accessing the object.

Fix:

To resolve the 55006 error, you need to ensure that the object is not being accessed by any other sessions when you perform the operation. Here are some examples of how to fix it:

Example 1: Dropping a database that is in use

-- This will cause an error if the database 'my_database' is currently being accessed
DROP DATABASE my_database;

-- To fix it, terminate all connections to the database before dropping it
SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE datname = 'my_database';

-- Now you can drop the database
DROP DATABASE my_database;

Example 2: Dropping a table that is in use

-- This will cause an error if the table 'my_table' is currently being accessed
DROP TABLE my_table;

-- To fix it, ensure that no sessions are using the table
-- You can check for active connections as shown previously and terminate them if necessary

-- Once no sessions are using the table, you can safely drop it
DROP TABLE my_table;

Example 3: Altering an object that is in use

-- This will cause an error if the object 'my_object' is currently being accessed
ALTER TABLE my_object ADD COLUMN new_column TEXT;

-- To fix it, ensure that no transactions are currently using 'my_object'
-- If the object is locked, you may need to wait for the transaction holding the lock to finish

-- Once the object is no longer in use, you can perform the alteration
ALTER TABLE my_object ADD COLUMN new_column TEXT;

Considerations:

  • It’s important to be cautious when terminating backend connections, as this can cause transactions to be aborted and may lead to data inconsistency if not handled properly.
  • If you’re working in a production environment, schedule maintenance operations during a window of low activity to minimize impact.
  • Always communicate with your team before terminating connections or dropping objects to ensure that no critical operations are interrupted.
  • If the operation is not urgent, consider waiting for a time when the object is not in use.

By carefully checking for active connections and ensuring that the object is not in use, you can fix the 55006 object_in_use error code in PostgreSQL. For more information on managing database connections and sessions, you can refer to the PostgreSQL documentation on session management.

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