Re: problem about maximum row size ?

Tom Lane wrote:
> zhaoxin <zhaox(at)necas(dot)nec(dot)com(dot)cn> writes:
> > I have a question about maximum row size .
> > In pgsql FAQ, I can find this description :
> > ...
> > Maximum size for a row? 1.6TB
> > ...
>
> > does it mean 1600 text column in a table and 1G every column ?
>
> > but, when I test this case by psqlodbc, I got some error :
>
> This was posted in a fairly randomly chosen list, but I think it does
> expose an error in the FAQ: you can't fit 1600 TOAST pointers into one
> row and so the 1.6TB figure is overoptimistic.
>
> Since TOAST pointers are 20 bytes, a reasonable number for the maximum
> number of large toasted fields is about 400, which would make the
> correct entry for this question 400Gb. This could be improved by using
> a non-default block size, so this should be listed as one of the limits
> affected by block size.

FAQ updated with new number, and mention that increasing block size
quadruples it.

--
Bruce Momjian http://candle.pha.pa.us

+ If your life is a hard drive, Christ can be your backup. +