"Brian Herlihy" <btherl@xxxxxxxxxxxx> writes: > There is a unique index mapping domains to domain_ids. ... > The issue: the second query results in a lower cost estimate. I am wondering > why the second query plan was not chosen for the first query. Well the unique index you mentioned is critical to being able to conclude the queries are equivalent. Postgres in the past hasn't been able to use things like unique indexes to make planning decisions because it had no infrastructure to replan if you dropped the index. We do have such infrastructure now so it may be possible to add features like this in the future. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com
