Hi
2015-12-18 16:21 GMT+01:00 Mathieu VINCENT :
> Hello,
>
> No one to help me to understand this bad estimation rows ?
> It's *NOT* caused by :
>
>- correlation between columns (cross-correlation)
>- bad statistics (i tried with default_statistics_target to 10 000)
>- bad number of
Hello,
No one to help me to understand this bad estimation rows ?
It's *NOT* caused by :
- correlation between columns (cross-correlation)
- bad statistics (i tried with default_statistics_target to 10 000)
- bad number of distinct values
- complexe join conditions
I have no more id
Adding foreign key between on t2 and t3, does not change the plan.
drop table if exists t1;
drop table if exists t2;
drop table if exists t3;
create table t1 as select generate_Series(1,20) as c1;
create table t2 as select generate_Series(1,20)%100+1 as c1;
create table t3 as select gener
Here, another issue with row estimate.
And, in this example, there is not correlation beetween columns in a same
table.
drop table if exists t1;
drop table if exists t2;
drop table if exists t3;
create table t1 as select generate_Series(1,20) as c1;
create table t2 as select generate_Series(1
Thank you both for the help!
happy holidays
2015-12-17 10:10 GMT+01:00 Mathieu VINCENT :
> thks Gunnar,
>
> I removed the correlation between t3.c1 and t3.c2 in this sql script :
>
> drop table if exists t1;
> drop table if exists t2;
> drop table if exists t3;
> drop table if exists t4;
>
> crea
thks Gunnar,
I removed the correlation between t3.c1 and t3.c2 in this sql script :
drop table if exists t1;
drop table if exists t2;
drop table if exists t3;
drop table if exists t4;
create table t1 as select generate_Series(1,30) as c1;
create table t2 as select generate_Series(1,400) as c
Am 15.12.2015 um 10:49 schrieb Andreas Kretschmer:
> Gunnar Nick Bluth wrote:
>
>> Am 15.12.2015 um 09:05 schrieb Mathieu VINCENT:
>>> Hello,
>>>
>>> No one to help me to understand this bad estimation rows ?
>>
>> Well,
>>
>> on a rather beefy machine, I'm getting quite a different plan:
>> http
Gunnar Nick Bluth wrote:
> Am 15.12.2015 um 09:05 schrieb Mathieu VINCENT:
> > Hello,
> >
> > No one to help me to understand this bad estimation rows ?
>
> Well,
>
> on a rather beefy machine, I'm getting quite a different plan:
> http://explain.depesz.com/s/3y5r
you are using 9.5, right? Go
Am 15.12.2015 um 09:05 schrieb Mathieu VINCENT:
> Hello,
>
> No one to help me to understand this bad estimation rows ?
Well,
on a rather beefy machine, I'm getting quite a different plan:
http://explain.depesz.com/s/3y5r
Which may be related to this setting:
perftest=# show default_statistics_
Hello,
No one to help me to understand this bad estimation rows ?
Mathieu VINCENT
2015-12-11 12:35 GMT+01:00 Mathieu VINCENT :
> Sorry, I forget to precise Postgresql version
>
> 'PostgreSQL 9.4.4 on x86_64-unknown-linux-gnu, compiled by gcc (GCC) 4.4.7
> 20120313 (Red Hat 4.4.7-11), 64-bit'
>
Sorry, I forget to precise Postgresql version
'PostgreSQL 9.4.4 on x86_64-unknown-linux-gnu, compiled by gcc (GCC) 4.4.7
20120313 (Red Hat 4.4.7-11), 64-bit'
BR
Mathieu VINCENT
2015-12-11 9:53 GMT+01:00 Mathieu VINCENT :
> Hello,
>
> I would like to know how row estimation is calculed by ex
Hello,
I would like to know how row estimation is calculed by explain ?
In my execution plan, this estimation is extremely wrong (267 instead of
198000)
I reproduced this estimation error in this simple case :
drop table if exists t1;
drop table if exists t2;
drop table if exists t3;
drop table i
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