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Re: insert vs select into performance

От: Arjen van der Meijden
Тема: Re: insert vs select into performance
Дата: ,
Msg-id: 469D1E4F.5090805@tweakers.net
(см: обсуждение, исходный текст)
Ответ на: insert vs select into performance  (Thomas Finneid)
Ответы: Re: insert vs select into performance  (Thomas Finneid)
Список: pgsql-performance

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insert vs select into performance  (Thomas Finneid, )
 Re: insert vs select into performance  (Michael Glaesemann, )
  Re: insert vs select into performance  (Tom Lane, )
   Re: insert vs select into performance  (Thomas Finneid, )
    Re: insert vs select into performance  (Michael Stone, )
     Re: insert vs select into performance  (Adriaan van Os, )
      Re: insert vs select into performance  (Heikki Linnakangas, )
  Re: insert vs select into performance  (Thomas Finneid, )
   Re: insert vs select into performance  (Michael Stone, )
   Re: insert vs select into performance  (Mark Lewis, )
    Re: insert vs select into performance  (Thomas Finneid, )
   Re: insert vs select into performance  (Michael Glaesemann, )
    Re: insert vs select into performance  (Thomas Finneid, )
 Re: insert vs select into performance  (Arjen van der Meijden, )
  Re: insert vs select into performance  (Thomas Finneid, )
   Re: insert vs select into performance  (Michael Stone, )
    Re: insert vs select into performance  (Thomas Finneid, )
     Re: insert vs select into performance  (Michael Stone, )
 Re: insert vs select into performance  (PFC, )
  Re: insert vs select into performance  (Thomas Finneid, )
   Re: insert vs select into performance  (PFC, )
    Re: insert vs select into performance  (Thomas Finneid, ) 
Have you also tried the COPY-statement? Afaik select into is similar to
what happens in there.

Best regards,

Arjen

On 17-7-2007 21:38 Thomas Finneid wrote:
> Hi
>
> I was doing some testing on "insert" compared to "select into". I
> inserted 100 000 rows (with 8 column values) into a table, which took 14
> seconds, compared to a select into, which took 0.8 seconds.
> (fyi, the inserts where batched, autocommit was turned off and it all
> happend on the local machine)
>
> Now I am wondering why the select into is that much faster?
> Does the select into translate into a specially optimised function in c
> that can cut corners which a insert can not do (e.g. lazy copying), or
> is it some other reason?
>
> The reason I am asking is that select into shows that a number of rows
> can be inserted into a table quite a lot faster than one would think was
> possible with ordinary sql. If that is the case, it means that if I
> write an pl-pgsql insert function in C instead of sql, then I can have
> my db perform order of magnitude faster.
>
> Any comments?
>
> regards
>
> thomas
>
> ---------------------------(end of broadcast)---------------------------
> TIP 6: explain analyze is your friend
>

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