Re: Random function
| От | David G. Johnston |
|---|---|
| Тема | Re: Random function |
| Дата | |
| Msg-id | CAKFQuwb7OBmDRGJg2HZPuS7EafJOiejaQO0UqZXvC20ZEnU6mQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Random function (Luis Roberto Weck <luisroberto@siscobra.com.br>) |
| Список | pgsql-performance |
How is this a performance related question?
On Tue, Mar 24, 2020 at 11:10 AM Luis Roberto Weck <luisroberto@siscobra.com.br> wrote:
However, I am getting the same result over mulitiple rows. This is a
sample of the SQL I am using:
select (select string_agg(random()::text,';')
from pg_catalog.generate_series(1,3,1) )
from generate_series(1,10,1)
And I am getting something like:
|string_agg |
+--------------------------------------------------------------+
|0.243969671428203583;0.692578794434666634;0.291524752043187618|
|0.243969671428203583;0.692578794434666634;0.291524752043187618|
|0.243969671428203583;0.692578794434666634;0.291524752043187618|
|0.243969671428203583;0.692578794434666634;0.291524752043187618|
|0.243969671428203583;0.692578794434666634;0.291524752043187618|
|0.243969671428203583;0.692578794434666634;0.291524752043187618|
|0.243969671428203583;0.692578794434666634;0.291524752043187618|
|0.243969671428203583;0.692578794434666634;0.291524752043187618|
|0.243969671428203583;0.692578794434666634;0.291524752043187618|
|0.243969671428203583;0.692578794434666634;0.291524752043187618|
If this is the expected output,
Yes, you've asked it to compute a value, assign it to a column, then generate 10 rows of that value.
is there a way to always generate random
numbers?
Don't use a scalar subquery in the main target list.
One possible answer:
select format('%s;%s;%s', random(), random(), random()) from generate_series(1, 10)
David J.
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