From: Bruce Momjian <pgman@candle.pha.pa.us>
To: The Hermit Hacker <scrappy@hub.org>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-admin@postgresql.org
Subject: Re: postgres limitation
Date: Sun, 28 Jan 2001 10:19:21 -0500 (EST)
Message-ID: <200101281519.KAA29591@candle.pha.pa.us> (raw)
In-Reply-To: <Pine.BSF.4.31.0101272201400.577-100000@thelab.hub.org>
I updated the maximum number of columns:
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? 250-1600 depending on column types
Maximum number of indexes on a table? unlimited
>
> 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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Subject: Re: postgres limitation
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