SYS_UDF_LOG - Amazon Redshift
Table columnsSample queries
Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

SYS_UDF_LOG

Records system-defined error and warning messages generated during user-defined function (UDF) execution.

SYS_UDF_LOG is visible only to superusers. For more information, see Visibility of data in system tables and views.

Table columns

Column name Data type Description
query_id bigint The query identifier.
function_name text The name of the user-defined function.
record_time timestamp The time that the record was created.
sequence integer The sequence of a single log message.
message text The log message text.

Sample queries

The following example shows how UDFs handle system-defined errors. The first block shows the definition for a UDF function that returns the inverse of an argument. When you run the function and provide a 0 as your argument, the function returns an error. The last statement returns the error message logged in SYS_UDF_LOG.

-- Create a function to find the inverse of a number.
CREATE OR REPLACE FUNCTION f_udf_inv(a int) 

RETURNS float 

IMMUTABLE AS $$return 1/a 

$$ LANGUAGE plpythonu; 

-- Run the function with 0 to create an error.
Select f_udf_inv(0); 

-- Query SYS_UDF_LOG to view the message.
Select query_id, record_time, message::varchar from sys_udf_log; 


query_id    |    record_time              |                 message
----------+----------------------------+-------------------------------------------------------
2211        | 2023-08-23 15:53:11.360538 |  ZeroDivisionError: integer division or modulo by zero line 2, in f_udf_inv\n return 1/a\n

The following example adds logging and a warning message to the UDF so that a divide by zero operation results in a warning message instead of stopping with an error message.

-- Create a function to find the inverse of a number and log a warning if you input 0.
CREATE OR REPLACE FUNCTION f_udf_inv_log(a int)
  RETURNS float IMMUTABLE
 AS $$ 
  import logging
  logger = logging.getLogger() #get root logger
  if a==0:
    logger.warning('You attempted to divide by zero.\nReturning zero instead of error.\n') 
    return 0
  else:
     return 1/a
$$ LANGUAGE plpythonu;

-- Run the function with 0 to trigger the warning.
Select f_udf_inv_log(0);

-- Query SYS_UDF_LOG to view the message.
Select query_id, record_time, message::varchar from sys_udf_log;

 query_id |        record_time         |                                    message
----------+----------------------------+-------------------------------------------------------------------------------
     0   | 2023-08-23 16:10:48.833503 | WARNING: You attempted to divide by zero.\nReturning zero instead of error.\n