Re: Is there a drawback when changing NAMEDATALEN to 64?

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От Bruce Momjian
Тема Re: Is there a drawback when changing NAMEDATALEN to 64?
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Msg-id 200201242349.g0ONnUZ05345@candle.pha.pa.us
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Ответ на Re: Is there a drawback when changing NAMEDATALEN to 64?  (Tom Lane <tgl@sss.pgh.pa.us>)
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Tom Lane wrote:
> Frank Joerdens <frank@joerdens.de> writes:
> > Is there a drawback when changing NAMEDATALEN to 64? Put the other way
> > 'round, what's the thinking behind having a default of 32?
>
> That value was chosen years ago, when machines were slower and disks
> smaller than today.
>
> There's been a proposal on the table for awhile to increase the standard
> NAMEDATALEN value to 64, but we haven't got round to it.
>
> BTW, there is at least a small potential for breaking applications with
> this change: NAMEDATALEN is part of the exported libpq ABI, because it
> affects the representation of PGnotify structures.  When and if we do
> change the standard setting, I'm inclined to reverse the order of the
> fields in PGnotify, so that accesses to be_pid don't depend on
> NAMEDATALEN.

TODO updated:

* Increase identifier length (NAMEDATALEN) if small performance hit;
  change struct pgNotify to use pid first, breaks notify API

--
  Bruce Momjian                        |  http://candle.pha.pa.us
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