Re: [SQL] EXTERNAL storage and substring on long strings

От: Tom Lane
Тема: Re: [SQL] EXTERNAL storage and substring on long strings
Дата: ,
Msg-id: 3574.1060012423@sss.pgh.pa.us
(см: обсуждение, исходный текст)
Ответ на: Re: EXTERNAL storage and substring on long strings  (Scott Cain)
Ответы: Re: [SQL] EXTERNAL storage and substring on long strings  (Scott Cain)
Re: [SQL] EXTERNAL storage and substring on long strings  (Jan Wieck)
Список: pgsql-performance

Скрыть дерево обсуждения

EXTERNAL storage and substring on long strings  (Scott Cain, )
 Re: EXTERNAL storage and substring on long strings  (Scott Cain, )
  Re: EXTERNAL storage and substring on long strings  (Tom Lane, )
  Re: EXTERNAL storage and substring on long strings  (Joe Conway, )
 Re: EXTERNAL storage and substring on long strings  (Scott Cain, )
  Re: EXTERNAL storage and substring on long strings  (Tom Lane, )
 Re: EXTERNAL storage and substring on long strings  (Joe Conway, )
  Re: EXTERNAL storage and substring on long strings  (Ron Johnson, )
   Re: EXTERNAL storage and substring on long strings  (Scott Cain, )
    Re: [SQL] EXTERNAL storage and substring on long strings  (Tom Lane, )
     Re: [SQL] EXTERNAL storage and substring on long strings  (Scott Cain, )
      Re: [SQL] EXTERNAL storage and substring on long strings  (Joe Conway, )
       Re: [SQL] EXTERNAL storage and substring on long strings  (Scott Cain, )
        Re: [SQL] EXTERNAL storage and substring on long strings  (Scott Cain, )
         Re: [SQL] EXTERNAL storage and substring on long strings  (Joe Conway, )
     Re: [SQL] EXTERNAL storage and substring on long strings  (Jan Wieck, )
      Re: [SQL] EXTERNAL storage and substring on long strings  (Tom Lane, )
       Re: [SQL] EXTERNAL storage and substring on long strings  (Scott Cain, )
       Re: [SQL] EXTERNAL storage and substring on long strings  (Jan Wieck, )
    Re: [SQL] EXTERNAL storage and substring on long strings  (Richard Huxton, )
     Re: [SQL] EXTERNAL storage and substring on long strings  (Scott Cain, )
      Re: [SQL] EXTERNAL storage and substring on long strings  ("Shridhar Daithankar", )
      Re: [SQL] EXTERNAL storage and substring on long strings  ("Matt Clark", )
  Re: EXTERNAL storage and substring on long strings  (Scott Cain, )
 Re: EXTERNAL storage and substring on long strings  (Tom Lane, )
 Re: EXTERNAL storage and substring on long strings  (Joe Conway, )
  Re: EXTERNAL storage and substring on long strings  (Scott Cain, )
 Re: EXTERNAL storage and substring on long strings  (Tom Lane, )
  Re: EXTERNAL storage and substring on long strings  (Joe Conway, )
   Re: EXTERNAL storage and substring on long strings  (Tom Lane, )
    Re: EXTERNAL storage and substring on long strings  (Scott Cain, )

Scott Cain <> writes:
> At least this appears to work and is much faster, completing substring
> operations like above in about 0.27 secs (that's about two orders of
> magnitude improvement!)

I find it really, really hard to believe that a crude reimplementation
in plpgsql of the TOAST concept could beat the built-in implementation
at all, let alone beat it by two orders of magnitude.

Either there's something unrealistic about your testing of the
dna_string function, or your original tests are not causing TOAST to be
invoked in the expected way, or there's a bug we need to fix.  I'd
really like to see some profiling of the poor-performing
external-storage case, so we can figure out what's going on.

            regards, tom lane


В списке pgsql-performance по дате сообщения:

От: Tom Lane
Дата:
Сообщение: Re: I can't wait too much: Total runtime 432478.44 msec
От: "Fernando Papa"
Дата:
Сообщение: Re: I can't wait too much: Total runtime 432478.44 msec