Re: [HACKERS] Re: Jesus, what have I done (was: LONG)

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От Bruce Momjian
Тема Re: [HACKERS] Re: Jesus, what have I done (was: LONG)
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Msg-id 199912121456.JAA04151@candle.pha.pa.us
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Ответ на Re: Jesus, what have I done (was: LONG)  (wieck@debis.com (Jan Wieck))
Список pgsql-hackers
> >    add code to write/read from long tables
> >    add code to expand long values in varlen access routines
> >    add code to heap_insert() to move data to long tables
> >    add code to heap_delete() to invalidate long tuples
> 
>     Add  code  to  expand  long values in varlen access routines,
>     you're joking - no?
> 
>     How many functions are there, called  via  the  fmgr  with  a
>     Datum as argument, and only knowing by themself (and a system
>     catalog) that they receive a variable length attribute?
> 
>     So you would better do the fetching in the fmgr. Then  again,
>     there  are  many  places  in  the  code (and possibly in user
>     extensions too), that call builtin functions  like  textout()
>     directly, passing it the Datum they got from somewhere.


You may be able to expand the in-tuple copy if you had a bit on the
tuple that said long fields exist, and do a heap_tuplecopy() only in
those cases.

You also could cache recently lookuped expand_long value so repeated
calls could return the value without reconstructing the long value.

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