Example: Performing correlated subqueries in Redshift Spectrum - Amazon Redshift
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Example: Performing correlated subqueries in Redshift Spectrum

You can perform correlated subqueries in Redshift Spectrum. The $spectrum_oid pseudocolumn provides the ability to perform correlated queries with Redshift Spectrum. To perform a correlated subquery, the pseudocolumn $spectrum_oid must be enabled but doesn't appear in the SQL statement. For more information, see Pseudocolumns.

To create the external schema and external tables for this example, see Getting started with Amazon Redshift Spectrum.

Following is an example of a correlated subquery in Redshift Spectrum.

select * from myspectrum_schema.sales s where exists ( select * from myspectrum_schema.listing l where l.listid = s.listid ) order by salesid limit 5;
salesid listid sellerid buyerid eventid dateid qtysold pricepaid commission saletime 1 1 36861 21191 7872 1875 4 728 109.2 2008-02-18 02:36:48 2 4 8117 11498 4337 1983 2 76 11.4 2008-06-06 05:00:16 3 5 1616 17433 8647 1983 2 350 52.5 2008-06-06 08:26:17 4 5 1616 19715 8647 1986 1 175 26.25 2008-06-09 08:38:52 5 6 47402 14115 8240 2069 2 154 23.1 2008-08-31 09:17:02