How to diagnose and fix the 38002 modifying_sql_data_not_permitted error code in Postgres.

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The 38002 error code in PostgreSQL corresponds to a situation where a modifying SQL operation is not permitted. This error is part of the SQL standard’s conventions for “SQLSTATE” codes and typically arises in environments where certain types of SQL operations are restricted, such as within a read-only transaction or function.

Here are some scenarios where this error might occur and how you can diagnose and fix it:

  1. Read-Only Transaction: If you are in a read-only transaction, you cannot perform operations that modify the database. To diagnose this, check if the transaction is explicitly set to read-only. To fix it, you need to end the current read-only transaction and start a new transaction without the read-only restriction.
   -- End the current read-only transaction
   COMMIT;

   -- Start a new read-write transaction
   BEGIN TRANSACTION READ WRITE;

   -- Perform your data modification operation
   INSERT INTO your_table(column1, column2) VALUES (value1, value2);
  1. Read-Only Function or Trigger: If the error occurs within a function or trigger, the function might be defined with the SECURITY DEFINER or SECURITY INVOKER attribute and is trying to modify data in a context where it’s not allowed. To fix this, you might need to redefine the function without the read-only restriction.
   -- Redefine the function without the read-only restriction
   CREATE OR REPLACE FUNCTION your_function() RETURNS void AS $$
   BEGIN
     -- Your code that modifies data
   END;
   $$ LANGUAGE plpgsql;
  1. Standby Server: If you’re working with a standby server in a replication setup, the server may be in recovery mode, and by default, it is read-only. To fix this, you would need to promote the standby server to a primary server, or perform write operations on the primary server instead.
   # Promote standby server to primary
   pg_ctl promote -D /path/to/standby/data/directory
  1. Role Permissions: The role executing the operation might not have the necessary permissions to modify the data. To diagnose this, check the role’s permissions with respect to the table or schema in question. To fix it, you can grant the appropriate permissions to the role.
   -- Grant the role permission to modify the table
   GRANT INSERT, UPDATE, DELETE ON your_table TO your_role;
  1. SQL Function with a Restrictive Security Definer: If the error occurs within a SQL function that has been created with a restrictive security definer, you may need to change the security context or adjust the function’s definer.
   -- Change the security context of the function
   ALTER FUNCTION your_function SECURITY INVOKER;

Remember to always perform such changes with caution, especially in a production environment, and ensure that the modifications align with your application’s security policies and requirements. The error code documentation on the PostgreSQL website can provide additional insights into the various error codes and their meanings.

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