Re: [HACKERS] tables > 1 gig

Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> writes:
>> Then we'd better fix the underlying problem. We can't change
>> RELSEG_SIZE for a minor release, unless you want to give up the
>> principle of not forcing initdb at minor releases.

> Why can't we increase it?

Consider a 1.5-gig table. 6.5 will store it as one gig in file "table",
one-half gig in file "table.1". Now recompile with larger RELSEG_SIZE.
The file manager will now expect to find all blocks of the relation in
file "table", and will never go to "table.1" at all. Presto, you lost
a bunch of data.

Bottom line is just as it says in the config.h comments: you can't
change either BLCKSZ or RELSEG_SIZE without doing initdb.

regards, tom lane