Re: Slow update on column that is part of exclusion constraint

So fair enough, it does seem to be related to the lookup rather than
maintenance on the index. I was misguided in my initial assumption.

Spent quite a bit of time trying to come up with a self contained test, and
it seems like I can't make it choose the GiST index unless I remove the
regular btree index in my test case, though the opposite is true for my
table in production. Not really sure what that means as far as what I need
to do though. I've tried a vacuum full, analyze, rebuild index, drop and
re-add the constraint... It still uses that GiST index for this query.

Hell, a sequential scan is a ton faster even.

On Wed, Apr 13, 2016 at 2:54 PM, Evgeniy Shishkin <itparanoia(at)gmail(dot)com>
wrote:

>
> > On 13 Apr 2016, at 20:14, Adam Brusselback <adambrusselback(at)gmail(dot)com>
> wrote:
> >
> > Sorry, brain stopped working and I forgot to include the normal info.
> >
> > Postgres version: 9.5.1
> > Hardware: 2 core, 4gb Digital Ocean virtual server
> > OS: Debian
> >
> > explain analyze for an example update:
> > 'Update on price_generated (cost=32.45..644.83 rows=1 width=157)
> (actual time=29329.614..29329.614 rows=0 loops=1)'
> > ' -> Nested Loop (cost=32.45..644.83 rows=1 width=157) (actual
> time=29329.608..29329.608 rows=0 loops=1)'
> > ' -> HashAggregate (cost=32.04..34.35 rows=231 width=52)
> (actual time=1.137..2.090 rows=231 loops=1)'
> > ' Group Key: pti.product_id, pti.company_id, pti.date_range'
> > ' -> Seq Scan on _prices_to_insert pti (cost=0.00..30.31
> rows=231 width=52) (actual time=0.060..0.678 rows=231 loops=1)'
> > ' -> Index Scan using
> price_generated_company_product_date_active_excl on price_generated
> (cost=0.41..2.63 rows=1 width=151) (actual time=126.949..126.949 rows=0
> loops=231)'
> > ' Index Cond: (date_range = pti.date_range)'
> > ' Filter: ((upper(active_range) IS NULL) AND
> (pti.product_id = product_id) AND (pti.company_id = company_id))'
> > ' Rows Removed by Filter: 29460'
> > 'Planning time: 3.134 ms'
> > 'Execution time: 29406.717 ms'
>
> Well, you see execution time of 30 seconds because there are 231 index
> lookups,
> each taking 126 ms.
>
> And that lookup is slow because of
> Filter: ((upper(active_range) IS NULL) AND (pti.product_id = product_id)
> AND (pti.company_id = company_id))'
>
> Can you provide self-containing example of update?
> I don't see there (upper(active_range) IS NULL condition is coming from.