From: andrew@ernie.2sheds.de
To: Bruce Momjian <pgman@candle.pha.pa.us>
Cc: The Hermit Hacker <scrappy@hub.org>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-admin@postgresql.org, PostgreSQL-documentation <pgsql-docs@postgresql.org>
Subject: Re: postgres limitation
Date: Sun, 28 Jan 2001 11:01:56 +0100
Message-ID: <20010128110156.A26946@ernie.2sheds.de> (raw)
In-Reply-To: <200101280244.VAA23569@candle.pha.pa.us>
References: <Pine.BSF.4.31.0101272201400.577-100000@thelab.hub.org>
<200101280244.VAA23569@candle.pha.pa.us>
Put both in,
the short for the managers who want to compare postgresql to
<insert generic brand sql server here>
and the long for the techies
Andrew
On Sat, Jan 27, 2001 at 09:44:12PM -0500, Bruce Momjian wrote:
> Can I get some feedback from the group? Should a long or short version
> be used in the FAQ?
>
> >
> > How about the full answer? I think Tom did a fantastic job of writing up,
> > be a shame to make it go to waste for brevity? :(
> >
> > On Sat, 27 Jan 2001, Bruce Momjian wrote:
> >
> > > OK, how is this?
> > >
> > >
> > > These are the limits:
> > >
> > > Maximum size for a database? unlimited (60GB databases exist)
> > > Maximum size for a table? 64 TB on all operating systems
> > > Maximum size for a row? unlimited in 7.1 and later
> > > Maximum size for a field? 1GB in 7.1 and later
> > > Maximum number of rows in a table? unlimited
> > > Maximum number of columns in a table? 1600
> > > Maximum number of indexes on a table? unlimited
> > >
> > > Of course, these are not actually unlimited, but limited to
> > > available disk space and memory/swap space. Performance may
> > > suffer when these values get unusually large.
> > >
> > > ---------------------------------------------------------------------------
> > >
> > >
> > >
> > > > Bruce, I think section 4.6 of the FAQ is a tad on the short and overly
> > > > optimistic side. Here's a set of more precise statements ...
> > > >
> > > >
> > > > 4.6) What is the maximum size for a row, table, database?
> > > >
> > > > Maximum size for a database?
> > > >
> > > > Effectively unlimited, although you may see performance problems with
> > > > more than a few thousand tables in a database, depending on how
> > > > gracefully your filesystem copes with directories containing many files.
> > > >
> > > > Maximum size for a table?
> > > >
> > > > 2G blocks, hence 16 to 64 terabytes depending on the BLCKSZ
> > > > configuration constant. (If someone were to run around and make sure
> > > > all the block-number arithmetic is unsigned, we could claim 4G blocks,
> > > > but I think it's not all unsigned now...)
> > > >
> > > > Maximum size for a row?
> > > >
> > > > See limits on field size and number of columns.
> > > >
> > > > Maximum size for an individual field value?
> > > >
> > > > Field values are limited to 1Gb, and in practice are more tightly
> > > > limited by memory/swap space available to a backend; a field value that
> > > > is a large fraction of the maximum process memory size will probably
> > > > cause out-of-memory failures.
> > > >
> > > > Maximum number of columns in a table?
> > > >
> > > > 1600. In practice probably quite a bit less, even with TOAST, since the
> > > > master tuple still has to fit in a block. If all the columns are large
> > > > (toastable) then at most you could fit about 250 columns with BLCKSZ=8K,
> > > > since an out-of-line TOAST value pointer takes 32 bytes. On the other
> > > > hand, 1600 int4 columns would fit easily.
> > > >
> > > > Maximum number of rows in a table?
> > > >
> > > > No specific limit. Note however that the COUNT() function currently
> > > > uses an int4 counter, so will give bogus results for more than 2G rows.
> > > >
> > > > Maximum number of indexes on a table?
> > > >
> > > > No limit.
> > > >
> > > > regards, tom lane
> > > >
> > >
> > >
> > > --
> > > Bruce Momjian | http://candle.pha.pa.us
> > > pgman@candle.pha.pa.us | (610) 853-3000
> > > + If your life is a hard drive, | 830 Blythe Avenue
> > > + Christ can be your backup. | Drexel Hill, Pennsylvania 19026
> > >
> >
> > Marc G. Fournier ICQ#7615664 IRC Nick: Scrappy
> > Systems Administrator @ hub.org
> > primary: scrappy@hub.org secondary: scrappy@{freebsd|postgresql}.org
> >
> >
>
>
> --
> Bruce Momjian | http://candle.pha.pa.us
> pgman@candle.pha.pa.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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Cc: andrew@ernie.2sheds.de, pgman@candle.pha.pa.us, scrappy@hub.org, tgl@sss.pgh.pa.us
Subject: Re: postgres limitation
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