views much slower in 9.3 than 8.4 - Mailing list pgsql-performance

From Carson, Leonard
Subject views much slower in 9.3 than 8.4
Date
Msg-id 510B084A-D218-4671-B16D-F28A9CF16235@ucsd.edu
Whole thread Raw
Responses Re: views much slower in 9.3 than 8.4  (Kevin Grittner <kgrittn@ymail.com>)
List pgsql-performance
We have views that run from 20x to failing to complete at all in 9.4.1 whereas they finished in seconds in 8.4.7 on the
sameplatform. 

After upgrading from 8.4 to 9.4, I ran ANALYZE on the entire DB.  Performance improved for some but not all of the
views.

Here is the explain-analyze output from one of the slow views in 9.4:
http://explain.depesz.com/s/36n

Unfortunately I have no way of producing an 8.4 plan.

While acknowledging that nested loops and sequential table scans account for 85% of the execution time which suggests
thata better query may be needed, why would the same query run in seconds on 8.x but take minutes on 9.x?    

Did the planner change significantly between the two releases?   Is there any way to compel the 9.4 planner to produce
an8.4 plan?   

Thanks in advance for you assistance.




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