Re: TOAST and TEXT

Bruce Momjian <pgman@candle.pha.pa.us>

From: Bruce Momjian <pgman@candle.pha.pa.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Chris Bitmead <chris@bitmead.com>, pgsql-hackers@postgresql.org
Date: 2001-10-13T04:13:32Z
Lists: pgsql-hackers
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > Although the field length is limited to 1GB, is there a row size
> > limit? 
> 
> Sure.  1Gb per field (hard limit) times 1600 fields (also hard limit).
> In practice less, since TOAST pointers are 20bytes each at present,
> meaning you can't have more than BLCKSZ/20 toasted fields in one row.

I read this as 409GB with 8k pages.

> Whether this has anything to do with real applications is debatable,
> however.  I find it hard to visualize a table design that needs several
> hundred columns that *all* need to be GB-sized.

Yes, that just makes my head hurt.  Easier to just say "unlimited" and
limited by your computer's memory/disk.

-- 
  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