PostgreSQL High Availability Cookbook - Second Edition

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There is one caveat to this functionality. It is not uncommon for databases to perform the write activity within a function body. For example:

CREATE FUNCTION test_insert() 
RETURNS VOID AS 
$$ 
  INSERT INTO foo SELECT generate_series(1, 100); 
$$ LANGUAGE SQL; 

By creating this function, we obfuscate the INSERT statement enough that pgpool won't recognize it. This means that pgpool will improperly send the query to a read-only server and produce an error. We can avoid this by using the black_function_list configuration setting. For example, if we add our new function to this setting, it resembles this:

black_function_list = 'currval,lastval,nextval,setval,test_insert' 

Now, pgpool will understand that queries that include a ...