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121031Re: [firebird-support] Why the difference?

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  • W O
    Mar 1, 2013
      Hello Mateusz

      But PER_IDENTI is the Primary Key, why Firebird needs a two-pass proccess?

      Greetings.

      Walter.





      On Fri, Mar 1, 2013 at 5:51 AM, Mateusz Loskot <mateusz@...> wrote:

      > **
      >
      >
      > On 1 March 2013 04:37, W O sistemas2000profesional@...> wrote:
      > > Somebody knows why there are a difference so big?
      > >
      > > I have a table with 3.600.000 rows more or less.
      > >
      > > Writing:
      > > SELECT * FROM V_ABM_PERSONAS V WHERE V.PER_IDENTI > 0 ROWS 1 TO 100
      > >
      > > takes 2.656 seconds (less than 3 seconds)
      > >
      > > Writing:
      > > SELECT * FROM V_ABM_PERSONAS V ORDER BY V.PER_IDENTI ROWS 1 TO 100
      > >
      > > takes more than 11 minutes!!!! (bored, I did cancel the execution)
      >
      > Think of it as single-pass versus two-pass processing.
      >
      > Best regards,
      > --
      > Mateusz Loskot, http://mateusz.loskot.net
      >
      >
      >


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