Re: Best way to get the latest revision from a table

От: Kevin Grittner
Тема: Re: Best way to get the latest revision from a table
Дата: ,
Msg-id: 4D3088E70200002500039632@gw.wicourts.gov
(см: обсуждение, исходный текст)
Ответ на: Re: Best way to get the latest revision from a table  (Shaun Thomas)
Ответы: Re: Best way to get the latest revision from a table  (Tom Lane)
Список: pgsql-performance

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Best way to get the latest revision from a table  (Nikolas Everett, )
 Re: Best way to get the latest revision from a table  ("Kevin Grittner", )
  Re: Best way to get the latest revision from a table  (Nikolas Everett, )
   Re: Best way to get the latest revision from a table  ("Kevin Grittner", )
 Re: Best way to get the latest revision from a table  (Shaun Thomas, )
  Re: Best way to get the latest revision from a table  ("Kevin Grittner", )
   Re: Best way to get the latest revision from a table  (Tom Lane, )
    Re: Best way to get the latest revision from a table  ("Kevin Grittner", )
     Re: Best way to get the latest revision from a table  (Nikolas Everett, )
      Re: Best way to get the latest revision from a table  (Shaun Thomas, )
      Re: Best way to get the latest revision from a table  (Robert Haas, )
       Re: Best way to get the latest revision from a table  (Nikolas Everett, )
    Re: Best way to get the latest revision from a table  (Shaun Thomas, )

Shaun Thomas <> wrote:

> This actually looks like a perfect candidate for DISTINCT ON.
>
> SELECT DISTINCT ON (a, b) a, b, revision
>    FROM test
>   ORDER BY a, b DESC;

I wouldn't say perfect.  It runs about eight times slower than what
I suggested and returns a fairly random value for revision instead
of the max(revision).

-Kevin


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