Zoltan Boszormenyi <zb(at)cybertec(dot)at> writes:
> At the end of the day, the behaviour is the same, isn't it?
No, there's a difference in terms of the priority for pushing this
column out to toast storage, versus pushing other columns of the row
out to toast. Normally we push the widest (remaining) column out,
and repeat, until the tuple is small enough. But MAIN columns stay
in, until there are no EXTENDED columns left.
regards, tom lane