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Re: PostgreSQL TPC-H test result?

From: "Jignesh K(dot) Shah" <J(dot)K(dot)Shah(at)Sun(dot)COM>
To: Greg Smith <gsmith(at)gregsmith(dot)com>
Cc: Amber <guxiaobo1982(at)hotmail(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: PostgreSQL TPC-H test result?
Date: 2008-09-12 03:30:39
Message-ID: 48C9E25F.4070203@sun.com (view raw or flat)
Thread:
Lists: pgsql-generalpgsql-performance
Moving this thread to Performance alias as it might make more sense for 
folks searching on this topic:



Greg Smith wrote:
> On Tue, 9 Sep 2008, Amber wrote:
>
>> I read something from 
>> http://monetdb.cwi.nl/projects/monetdb/SQL/Benchmark/TPCH/index.html 
>> saying that PostgreSQL can't give the correct result of the some 
>> TPC-H queries
>
> Jignesh Shah at Sun ran into that same problem.  It's mentioned 
> briefly in his presentation at 
> http://blogs.sun.com/jkshah/entry/postgresql_east_2008_talk_postgresql 
> on pages 26 and 27.  5 of the 22 reference TCP-H queries (4, 5, 6, 10, 
> 14) returned zero rows immediately for his tests.  Looks like the 
> MonetDB crew is saying it does that on queries 4,5,6,10,12,14,15 and 
> that 20 takes too long to run to generate a result.  Maybe 12/15/20 
> were fixed by changes in 8.3, or perhaps there were subtle errors 
> there that Jignesh didn't catch--it's not like he did a formal 
> submission run, was just kicking the tires.  I suspect the difference 
> on 20 was that his hardware and tuning was much better, so it probably 
> did execute fast enough.

I redid a quick test with the same workload on one of my systems with SF 
10 which is about 10GB
(I hope it comes out properly displayed)

     Jignesh        From Monet     (8.3T/8.2.9)

Q  Time PG8.3.3    Time PG8.2.9     Ratio

1    429.01              510        0.84

2      3.65               54        0.07

3     33.49              798        0.04

4      6.53    Empty      35  (E)   0.19

5      8.45    Empty       5.5(E)   1.54

6     32.84    Empty     172  (E)   0.19

7    477.95              439        1.09

8     58.55              251        0.23

9    781.96             2240        0.35

10     9.03    Empty       6.1(E)   1.48

11     3.57    Empty      25        0.14

12    56.11    Empty     179  (E)   0.31

13    61.01              140        0.44

14    30.69    Empty     169  (E)   0.18

15    32.81    Empty     168  (E)   0.2

16    23.98              115        0.21

17    Did not finish     Did not finish

18    58.93              882        0.07

19    71.55              218        0.33

20    Did not finish     Did not finish

21   550.51              477        1.15

22     6.21         Did not finish   



All time is in seconds (sub seconds where availabe)
Ratio > 1 means 8.3.3 is slower and <1 means 8.3.3 is faster

My take on the results:

* I had to tweak the statement of Q1 in order to execute it.
  (TPC-H kit does not directly support POSTGRESQL statements)

* Timings with 8.3.3 and bit of tuning gives much better time overall
  This was expected (Some queries finish in 7% of the time than what
  MonetDB reported. From the queries that worked only Q7 & Q21 seem to
  have regressed)

* However Empty rows results is occuring consistently
  (Infact Q11 also returned empty for me while it worked in their test)
  Queries: 4,5,6,10,11,12,14,15
  (ACTION ITEM: I will start separate threads for each of those queries in
   HACKERS alias to figure out the problem since it looks like Functional
   problem to me and should be interesting to hackers alias)

* Two queries 17,20 looks like will not finish (I let Q17 to run for 18 
hrs and
  yet it had not completed. As for Q20 I killed it as it was approaching 
an hour.)
  (ACTION ITEM: Not sure whether debugging for these queries will go in 
hackers or
   perform alias but I will start a thread on them too.)

* Looks like bit of tuning is required for Q1, Q7, Q9, Q21 to improve their
  overall time. Specially understanding if PostgreSQL is missing a more 
efficient
  plan for them.
  (ACTION ITEM: I will start separate threads on performance alias to 
dig into
   those queries)


I hope to start separate threads for each queries so we can track them 
easier. I hope to provide explain analyze outputs for each one of them 
and lets see if there are any problems.

Feedback welcome on what you want to see for each threads.

Regards,
Jignesh


-- 
Jignesh Shah           http://blogs.sun.com/jkshah  			
Sun Microsystems,Inc   http://sun.com/postgresql


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