Re: default statistics target testing (was: Simple postgresql.conf wizard) - Mailing list pgsql-hackers

From Greg Smith
Subject Re: default statistics target testing (was: Simple postgresql.conf wizard)
Date
Msg-id Pine.GSO.4.64.0812051321080.794@westnet.com
Whole thread Raw
In response to Re: default statistics target testing (was: Simple postgresql.conf wizard)  ("Robert Haas" <robertmhaas@gmail.com>)
Responses Re: default statistics target testing (was: Simple postgresql.conf wizard)
List pgsql-hackers
Looks like Robert accidentally answered my question about what version his 
results were from off-list.  Here's his update:

---

Unfortunately it was 8.2.9, as I realized halfway into the run.  Here are 
the results from a CVS HEAD checkout last night.

*** Query planning times

q1 (the complex one): 367 ms with default_statistics_target = 10, 379
ms with default_statistics_target = 1000 (3% slowdown)
other 6 queries: 18.48 ms with default_statistics_target = 10, 21.75
ms with default_statistics_target = 1000 (18% slowdown)

comparing to 8.2.9 results:
- q1 was 32% slower with dst = 10, 33% slower with dst = 1000
- other queries were 19% slower with dst = 10, 25% slower with dst = 1000

*** ANALYZE times

10      4.283007
20      6.741417
30      9.157209
40      11.445861
50      13.466374
60      15.402897
70      17.365484
80      19.243842
90      20.905635
100     22.643275
150     29.056517
200     31.878688
250     34.240638
300     36.996304
350     39.921178
400     42.443728
450     44.69833
500     47.553414
550     50.305143
600     52.799597
650     54.961691
700     57.117117
750     58.847345
800     61.60112
850     63.020136
900     65.858213
950     68.072528
1000    69.861321

comparing to 8.2.9 results:
- 3x faster with default_statistics_target = 10
- 4.25x faster with default_statistics_target = 1000

...Robert




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