Good day,
I have included a link to the result of EXPLAIN ANALYZE. It's this one:
https://app.box.com/s/u8nk6qvkjs4ae7l7dh4h
Here's a link to Depesz's explain (if links to the site are okay):
http://explain.depesz.com/s/gCk
I have just tried setting geqo_threshold, join_collapse_limit and from_collapse_limit to 16, but it yielded no improvement.
Changing those three parameters to 32 did speed up the query from about 3.3 seconds to about a second (give or take 50 ms), which is a pretty good improvement, but not quite there, as I'm looking to bring it down to about 300 ms if possible. Changing those three settings to 48 yielded no improvements over 32.
Is there possibly something something else to tweak there?
Here's EXPLAIN ANALYZE output when the three settings have been set to 32:
http://explain.depesz.com/s/cj2
Thank you.
Peter Slapansky
______________________________________________________________
> Od: Pavel Stehule <pavel.stehule@xxxxxxxxx>
> Komu: <slapo@xxxxxxxxxx>
> Dátum: 06.08.2013 21:01
> Predmet: Re: Sub-optimal plan for a paginated query on a view with another view inside of it.
>
> CC: pgsql-performance@xxxxxxxxxxxxxx
Hello
please, send result of EXPLAIN ANALYZE
please, use a http://explain.depesz.com/ for saving a plan
there is a more than 8 joins - so try to set geqo_threshold to 16,
join_collapse_limit to 16, and from_collapse_limit to 16.
Regards
Pavel Stehule
2013/8/2 <slapo@xxxxxxxxxx>:
> Good day,
>
> I have a performance issue when JOINing a view within another view more than once.
> The query takes over three seconds to execute, which is too long in this case. It's not a problem if the tables are nearly empty, but that isn't the case on the production database.
>
> I suspect the planner thinks it's better to first put together the v_address view and JOIN it to the parcel table later on, but the function "fx_get_user_tree_subordinates_by_id" should be JOINed to the parcel table first, as it reduces the number of rows to less than 200 and any following JOINs would be much faster.
>
> I have also ran vacuum, reindex and analyze on the whole database, but it seems to have had to effect.
>
> Is there any way to nudge the planner toward that way of execution?
>
> This is the query:
> https://app.box.com/s/jzxiuuxoyj28q4q8rzxr
>
> This is the query plan:
> https://app.box.com/s/u8nk6qvkjs4ae7l7dh4h (plain text)
> https://app.box.com/s/jzxiuuxoyj28q4q8rzxr (graphical output)
>
> These are the views:
> https://app.box.com/s/uibzidsazwv3eeauovuk (paginated view)
> https://app.box.com/s/v71vyexmdyl97m4f3m6u (used three times in the paginated view).
>
>
> Thank you.
>
> Peter Slapansky
>
>
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