The above "Or it can be almost 200 GB if the page has just pointers to 1GB TOAST items."
should read "Or it can be almost 200 GB *for a single page* if the page has just pointers to 1GB TOAST items." On Sat, Mar 28, 2026 at 4:32 PM Hannu Krosing <[email protected]> wrote: > > The issue is that currently the value is given in "main table pages" > and it would be somewhat deceptive, or at least confusing, to try to > express this in any other unit. > > As I explained in the commit message: > > ---------8<-------------------8<-------------------8<---------------- > This --max-table-segment-pages number specifically applies to main table > pages which does not guarantee anything about output size. > The output could be empty if there are no live tuples in the page range. > Or it can be almost 200 GB if the page has just pointers to 1GB TOAST items. > ---------8<-------------------8<-------------------8<---------------- > > And I can think of no cheap and reliable way to change that equation. > > I'll be very happy if you have any good ideas for either improving the > flag name, or even propose a way to better estimate the resulting dump > file size so we could give the chunk size in better units > > --- > Hannu > > > > > > On Sat, Mar 28, 2026 at 12:26 PM Michael Banck <[email protected]> wrote: > > > > Hi, > > > > On Tue, Jan 13, 2026 at 03:27:25PM +1300, David Rowley wrote: > > > Perhaps --max-table-segment-pages is a better name than > > > --huge-table-chunk-pages as it's quite subjective what the minimum > > > number of pages required to make a table "huge". > > > > I'm not sure that's better - without looking at the documentation, > > people might confuse segment here with the 1GB split of tables into > > segments. As pg_dump is a very common and basic user tool, I don't think > > implementation details like pages/page sizes and blocks should be part > > of its UX. > > > > Can't we just make it a storage size, like '10GB' and then rename it to > > --table-parallel-threshold or something? I agree it's bikeshedding, but > > I personally don't like either --max-table-segment-pages or > > --huge-table-chunk-pages. > > > > > > Michael
