The following bug has been logged on the website:
Bug reference: 12859
Logged by: lcarson
Email address: lcarson@sdsc.edu
PostgreSQL version: 9.4.1
Operating system: redhat 6
Description:
We have views that are running anywhere from 20x slower to failing to
complete in 9.4.1 whereas in 8.4.7 they produced results in seconds or tens
of seconds on the same platform.
After upgrading from 8.4 to 9.3, I ran ANALYZE on the entire db and it DID
improve performance for some, but not all, of the views in question.
Here is an explain plan of one of the slow views in 9.4:
http://explain.depesz.com/s/36n
While acknowledging that nested loops and sequential scans account for 85%
of the execution time, why would this run in seconds in 8.4 and minutes in
9.4? Is it because of changes to the planner?