2016-08-18 21:40 GMT+03:00 Victor Yegorov :
> Oh, that's interesting. I was under impression, that r_p_c reflects IO
> speed, like — make it smaller for SSDs.
> To make this query prefer BitmapScan, I need to bump r_p_c to 5.8. And 6.0
> makes it switch to SeqScan.
>
I was lo
2016-08-18 23:06 GMT+03:00 Jeff Janes :
> It does account for them, but perhaps not perfectly. See "[PERFORM]
> index fragmentation on insert-only table with non-unique column" for
> some arguments on that which might be relevant to you.
>
Thanks for pointing this out, good stuff to know.
If y
2016-08-18 18:59 GMT+03:00 Jeff Janes :
> Both plans touch the same pages. The index scan just touches some of
> those pages over and over again. A large setting of
> effective_cache_size would tell it that the page will most likely
> still be in cache when it comes back to touch it again, meani
2016-08-18 16:56 GMT+03:00 Tom Lane :
> In that case you've got random_page_cost too far down. Values less than
> the default of 4 are generally only appropriate if the bulk of your
> database stays in RAM.
>
Oh, that's interesting. I was under impression, that r_p_c reflects IO
speed, like — ma
Greetings.
I have a question on why planner chooses `IndexScan` for the following
query:
SELECT la.loan_id, la.due_date, la.is_current
FROM loan_agreements la WHERE la.is_current AND '2016-08-11' >
la.due_date;
Relevant (cannot post it all, sorry) table definition is:
2014-10-05 21:57 GMT+03:00 Andrey Lizenko :
> Increasing of 'effective_cache_size' leads to similar thing with
> mergejoin,
> other options (work_mem, shared_buffers. etc) do not change anything.
>
I think increasing `work_mem` should have effects, as plan with `Nested
Loop` is using disk-based
2014-09-26 17:04 GMT+03:00 Matúš Svrček :
> I am having a performance issue after upgrade from 8.4.20-1 -> 9.3.5.
First, make sure you have your statistics up to date — execute manual
`VACUUM ANALYZE`.
And then provide `EXPLAIN analyze` for 8.4 and `EXPLAIN (analyze, buffers)`
for 9.3 output.
2014-08-29 7:28 GMT+03:00 Burgess, Freddie :
>-> Index Scan using idx_clone_report_query_y201408 on
> SARS_IMPACT_REPORT_y2014m08 this__2 (cost=0.57..5570.95 rows=103
> width=136) (actual time=8.300..33308.118 rows=710202 loops=1)
> Index Cond: ((model_uid =
2014-08-28 14:29 GMT+03:00 gmb :
> Unfortunately , I don't have a lot of memory available ( 65 connections ,
> work_mem = 64MB in pg conf ).
>
You don't have to change cluster-wide settings here.
You can issue `SET` command from your client right before running your
query, only your session will
2014-08-28 12:08 GMT+03:00 gmb :
> GroupAggregate (cost=303425.31..339014.43 rows=136882 width=48) (actual
> time=4708.181..6688.699 rows=287268 loops=1)
> Buffers: shared read=23899, temp read=30974 written=30974
> -> Sort (cost=303425.31..306847.34 rows=1368812 width=48) (actual
> time=47
2014-08-28 11:50 GMT+03:00 gmb :
> It seems as if the planner is not using the PRIMARY KEY as index which was
> my assumption.
>
Can you send `EXPLAIN (analyze, buffers)` for your query instead?
It'll show exactly what's going on.
--
Victor Y. Yegorov
2013/6/26 Willy-Bas Loos
> postgres does a seqscan, even though there is an index present and it
> should be much more efficient to use it.
> I tried to synthetically reproduce it, but it won't make the same choice
> when i do.
> I can reproduce it with a simplified set of the data itself though.
2013/5/15 Robert Haas
> > Original query looks like this ( http://explain.depesz.com/s/pzv ):
> >
> > After a while I added row_number() to the inner part (
> > http://explain.depesz.com/s/hfs ):
> >
> > It was really surprising to see a "side" effect of 8x performance boost.
> > The only differe
2013/3/11 Jeff Adams - NOAA Affiliate
> Greetings,
>
>
>
> I have a large table (~90 million rows) containing vessel positions.
>
>
> ...
>
>
>
Could you kindly provide a script to create the table and populate it with
several sample
rows, please? Also, provide the desired output for the sample
2013/3/4 Joseph Pravato
> We are having a performance issue with our views in PostgreSQL and based
> on the requirements for assistance you recommend providing the full table
> and index schema besides additional information from this site.
> https://wiki.postgresql.org/wiki/Slow_Query_Questions
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