Re: return text from explain

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От Willy-Bas Loos
Тема Re: return text from explain
Дата
Msg-id CAHnozTiUBf+zT1tNVgEietyQcUV4qie1-oo8R7D38pf4NcamTQ@mail.gmail.com
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Ответ на Re: return text from explain  (Bruce Momjian <bruce@momjian.us>)
Список pgsql-general
Buce, thx for answering.
I cant't find the example you mean.
Tried a function, but won't work..

create or replace function test() returns setof record as $$
declare
t_rec record;
begin
for t_rec in (
explain
 select *
from (values ('a'),('b'), ('c')) foo(x)
where x > 'a'
) loop
    return next t_rec;
end loop;
end;
$$ language plpgsql;


select *
from test() as (x text)

ERROR:  syntax error at or near "explain"
LINE 6: explain

When i comment-out the "explain", then it works.
You can also run the query from "explain" to  "x > 'a'".

Cheers,

WBL

On Thu, Sep 6, 2012 at 8:03 PM, Bruce Momjian <bruce@momjian.us> wrote:
On Thu, Sep  6, 2012 at 07:18:50PM +0200, Willy-Bas Loos wrote:
> Hi,
>
> Is it possible to use the output of explain as text values?
> This won't work:
>
> explain select *
> from (values (1),(2),(3)) foo(x)
> where x > 2
>
> What i really want is to explain analyze a dynamic query that i build up in a
> function.
> If it returns a value i can do stuff with it, but i can't find out how to grasp
> the query plan as a value.
>
> pgAdmin shows it as text values in the data output tab, but that might be a
> hack outside the database realm.

I think you have to do EXPLAIN in a function and call the function.  My
CTE presentation has an example of that:

        http://momjian.us/main/presentations/features.html#cte

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +



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