Re: [GENERAL] Creation of tsearch2 index is very slow

От: Tom Lane
Тема: Re: [GENERAL] Creation of tsearch2 index is very slow
Дата: ,
Msg-id: 6111.1137797436@sss.pgh.pa.us
(см: обсуждение, исходный текст)
Ответ на: Re: [GENERAL] Creation of tsearch2 index is very slow  (Ron)
Ответы: Re: [GENERAL] Creation of tsearch2 index is very slow  ("Steinar H. Gunderson")
Re: [GENERAL] Creation of tsearch2 index is very slow  (Martijn van Oosterhout)
Список: pgsql-performance

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Re: [GENERAL] Creation of tsearch2 index is very slow  (Tom Lane, )
 Re: [GENERAL] Creation of tsearch2 index is very slow  (Martijn van Oosterhout, )
  Re: [GENERAL] Creation of tsearch2 index is very slow  (Tom Lane, )
   Re: [GENERAL] Creation of tsearch2 index is very slow  (Martijn van Oosterhout, )
    Re: [GENERAL] Creation of tsearch2 index is very slow  (Tom Lane, )
     Re: [GENERAL] Creation of tsearch2 index is very slow  (Martijn van Oosterhout, )
      Re: [GENERAL] Creation of tsearch2 index is very slow  ("Steinar H. Gunderson", )
      Re: [GENERAL] Creation of tsearch2 index is very slow  (Tom Lane, )
       Re: [GENERAL] Creation of tsearch2 index is very slow  ("Steinar H. Gunderson", )
        Re: [GENERAL] Creation of tsearch2 index is very slow  (Ron, )
         Re: [GENERAL] Creation of tsearch2 index is very slow  ("Steinar H. Gunderson", )
       Re: [GENERAL] Creation of tsearch2 index is very slow  (Martijn van Oosterhout, )
       Re: [GENERAL] Creation of tsearch2 index is very slow  ("Steinar H. Gunderson", )
      Re: [GENERAL] Creation of tsearch2 index is very slow  (Ron, )
       Re: [GENERAL] Creation of tsearch2 index is very slow  ("Steinar H. Gunderson", )
       Re: [GENERAL] Creation of tsearch2 index is very slow  (Tom Lane, )
        Re: [GENERAL] Creation of tsearch2 index is very slow  ("Steinar H. Gunderson", )
         Re: [GENERAL] Creation of tsearch2 index is very slow  (Tom Lane, )
          Re: [GENERAL] Creation of tsearch2 index is very slow  ("Steinar H. Gunderson", )
           Re: [GENERAL] Creation of tsearch2 index is very slow  (Tom Lane, )
            Re: [GENERAL] Creation of tsearch2 index is very slow  ("Steinar H. Gunderson", )
            Re: [GENERAL] Creation of tsearch2 index is very slow  ("Craig A. James", )
            Re: [GENERAL] Creation of tsearch2 index is very  (Ron, )
             Re: [GENERAL] Creation of tsearch2 index is very  (Oleg Bartunov, )
              Re: [GENERAL] Creation of tsearch2 index is very  (Ron, )
             Re: [GENERAL] Creation of tsearch2 index is very  (Tom Lane, )
              Re: [GENERAL] Creation of tsearch2 index is very  (David Lang, )
               Re: [GENERAL] Creation of tsearch2 index is very  (Tom Lane, )
              Re: [GENERAL] Creation of tsearch2 index is very  (Ron, )
               Re: [GENERAL] Creation of tsearch2 index is very  (Alvaro Herrera <-ip.org>, )
                Re: [GENERAL] Creation of tsearch2 index is very  (Ron, )
                 Re: [GENERAL] Creation of tsearch2 index is very  ("Craig A. James", )
                  Re: [GENERAL] Creation of tsearch2 index is very  (Ron, )
        Re: [GENERAL] Creation of tsearch2 index is very slow  (Martijn van Oosterhout, )
         Re: [GENERAL] Creation of tsearch2 index is very slow  (Oleg Bartunov, )
          Re: [GENERAL] Creation of tsearch2 index is very slow  (Martijn van Oosterhout, )
           Re: [GENERAL] Creation of tsearch2 index is very slow  (Oleg Bartunov, )
            Re: [GENERAL] Creation of tsearch2 index is very slow  (Martijn van Oosterhout, )
           Re: [GENERAL] Creation of tsearch2 index is very slow  (Oleg Bartunov, )
       Re: [GENERAL] Creation of tsearch2 index is very slow  (Martijn van Oosterhout, )
      Re: [GENERAL] Creation of tsearch2 index is very  (Ron, )
 Re: [GENERAL] Creation of tsearch2 index is very  (Oleg Bartunov, )

Ron <> writes:
> For an even more extreme speedup, don't most modern CPUs have an asm
> instruction that counts the bits (un)set (AKA "population counting")
> in various size entities (4b, 8b, 16b, 32b, 64b, and 128b for 64b
> CPUs with SWAR instructions)?

Yeah, but fetching from a small constant table is pretty quick too;
I doubt it's worth getting involved in machine-specific assembly code
for this.  I'm much more interested in the idea of improving the
furthest-distance algorithm in gtsvector_picksplit --- if we can do
that, it'll probably drop the distance calculation down to the point
where it's not really worth the trouble to assembly-code it.

            regards, tom lane


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