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Re: postgres limitation

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: The Hermit Hacker <scrappy(at)hub(dot)org>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-admin(at)postgresql(dot)org
Subject: Re: postgres limitation
Date: 2001-01-28 15:19:21
Message-ID: 200101281519.KAA29591@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-adminpgsql-docs
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(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
> >
> 
> Marc G. Fournier                   ICQ#7615664               IRC Nick: Scrappy
> Systems Administrator @ hub.org
> primary: scrappy(at)hub(dot)org           secondary: scrappy(at){freebsd|postgresql}.org
> 
> 


-- 
  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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