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Re: Removal of temp tables

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PostgreSQL-patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: Removal of temp tables
Date: 2001-06-14 18:18:29
Message-ID: 200106141818.f5EIITw15401@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > What else do we do with them except sorts?
> 
> Hash joins.  Materialize nodes.  Not to mention that sorting is used for
> things that aren't obviously sorts (SELECT count(distinct foo), for
> example).

Oh, I didn't know that.  OK.

> > Seems
> > pid_ was a good file name because they are always based on pid in
> > storage/file/fd.c.  The directory could be called simply 'tempfile' with
> > no pg_.  How is that?
> 
> You had that to begin with, and I changed it because I thought it was a
> bad idea.  The directory name and file name should both make perfectly
> clear that the files are temp files belonging to Postgres.  For example,
> it would be unsafe to make pg_tempfiles be a symlink pointing to a temp
> directory shared with other apps if there was any risk of temp file name
> collisions.  (Not sure you'd do that anyway, because of security issues,
> but let's not foreclose it with a poor choice of file names.)  A purely
> numeric file name for temp files is a particularly bad idea because it
> looks too much like our numeric names for table data files.  Don't
> eliminate a hypothetical confusion factor between relnames and filenames
> (which are never seen in the same context anyway) by introducing one
> between filenames and other filenames.

OK, I see, you think it could share a directory with another app.  Now I
see why you used pg_temp.

> 
> If you don't like pg_temp here, maybe post_temp?  pgsql_temp?

OK, pgsql_temp works for me.  Everytime I see pg_ I think system table. 
I will use pgsql_temp for directory and file names.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

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