Re: [GENERAL] Weird performance difference

On 2017-10-20 16:38, Tom Lane wrote:
> Israel Brewster <israel@ravnalaska.net> writes:
>>> Can you send "explain" (not explain analyze) for the production 
>>> server?
> 
>> Not for the full query - it only just completed, after 70 minutes or 
>> so, and I wasn't running under EXPLAIN ANALYZE. Running with a shorter 
>> date range of only 7 days, as you suggest below: 
>> https://explain.depesz.com/s/r80j <https://explain.depesz.com/s/r80j>
> 
> First thing that jumps out from that is
> 
>> Foreign Scan on oag_schedules (cost=100.00..128.60 rows=620 width=108) 
>> (actual time=3.576..477.524 rows=79,853 loops=1)
> 
> Being off by a factor of 100 at the scan level is never a good start 
> for a
> join plan.  Turn on use_remote_estimate (assuming these are 
> postgres_fdw
> tables).  Also try explicitly ANALYZE'ing the foreign tables.  I do not
> believe auto-analyze will touch foreign tables ...

Thanks - the ANALYZE apparently did it. Running the FULL query (for the 
entire year) now returns in slightly better time than my test machine: 
https://explain.depesz.com/s/GtiM

Also, the query plan now looks similar. So now that it's working, I can 
move on to optimizing. It's already been suggested that I remove the 
cast to date (or index it), so I guess that's the first thing I'll try.

> 
>             regards, tom lane


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