Yes, I see the one note that running Analyze can improve the performance. But in our testing under the same optimization and conditions INNER JOIN is significantly outperforming IN.
----- Original Message ---- From: Tom Lane t...@sss.pgh.pa.us Thomas Hamilton <thomashamilto...@yahoo.com> writes: > Apparently the latest version of MySQL has solved this problem: > http://www.xaprb.com/blog/2006/06/28/why-large-in-clauses-are-problematic/ > But I am running PostgreSQL v8.3 and am observing generally that SELECT ... > WHERE ... IN (a, b, c, ...) is much slower than SELECT ... INNER JOIN (SELECT > a UNION ALL SELECT b UNION ALL SELECT c ...) > Why doesn't the optimizer automatically transform IN clauses to INNER JOINs > in this fashion? Did you read all the comments on that three-year-old article? regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
