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Re: Thanks, naming conventions, and count()

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: Casey Lyon <casey(at)earthcars(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Thanks, naming conventions, and count()
Date: 2001-04-30 06:08:01
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Lists: pgsql-hackers
Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> big problem is that there is no good way to make the symlinks reliable
> because in a crash, the symlink could point to a table creation that got
> rolled back or the renaming of a table that got rolled back.

Yes.  Have you already forgotten the very long discussion we had about
this some months back?  There is no way to provide a reliable symlink
mapping without re-introducing all the same problems that we went to
numeric filenames to avoid.  Now if you want an *UNRELIABLE* symlink
mapping, maybe we could talk about it ... but IMHO such a feature would
be worse than useless.  Murphy's law says that the symlinks would be
right often enough to mislead dbadmins into trusting them, and wrong
exactly when it would do the most damage to trust them.  The same goes
for other methods of unreliably exporting the name-to-number mapping,
such as dumping it into a flat file.

We do need to document how to get the mapping (ie, select relfilenode,
relname from pg_class).  But I really doubt that an automated method
for exporting the mapping would be worth the cycles it would cost,
even if it could be made reliable which it can't.

			regards, tom lane

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