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Identifying queries with nested loops - Amazon Redshift

Amazon Redshift will no longer support the use of Python UDFs after June 30, 2026. We will start enforcing it in phases. For more information on the details of Python end of life and migration options, see the blog post that was published on June 30, 2025.

Identifying queries with nested loops

The following query identifies queries that have had alert events logged for nested loops. For information on how to fix the nested loop condition, see Nested loop.

select query, trim(querytxt) as SQL, starttime from stl_query where query in ( select distinct query from stl_alert_event_log where event like 'Nested Loop Join in the query plan%') order by starttime desc;