Thread

1. ISBN range table

   Thomas Munro <thomas.munro@gmail.com> — 2026-04-12T11:37:19Z

   Hi,
   
   A recent-ish thread[1] made me wonder what that big table of data
   does, and why we have a random update every decade or so, and I came
   up with the attached.
   
   It's pretty low stakes stuff: it controls where hyphens are inserted.
   This happens when new ranges are carved out for publishers, so to pick
   an example ISBN plucked from Wikipedia[2], here's an ISBN that is
   shown differently after the attached:
   
   postgres=# select '9791186178140'::isbn;
         isbn
   -----------------
    979-118617814-0
   (1 row)
   
   postgres=# select '9791186178140'::isbn;
          isbn
   -------------------
    979-11-86178-14-0
   
   [1] https://www.postgresql.org/message-id/flat/e0a62134-83da-4ba4-8cdb-ceb0111c95ce@eisentraut.org
   [2] https://en.wikipedia.org/wiki/List_of_ISBN_registration_groups
   

2. Re: ISBN range table

   Thomas Munro <thomas.munro@gmail.com> — 2026-04-14T03:04:32Z

   On Sun, Apr 12, 2026 at 11:37 PM Thomas Munro <thomas.munro@gmail.com> wrote:
   > A recent-ish thread[1] made me wonder what that big table of data
   > does, and why we have a random update every decade or so, and I came
   > up with the attached.
   
   Fixed a couple of typos and added as commitfest #6676.  The idea is
   that update_isbn.py would become another periodic update task, similar
   to Unicode, contrib/unaccent and the IANA timezone stuff.  I suppose
   running it only for major releases would be enough for such
   non-critical data.  There are also some other much smaller tables in
   this contrib module, but they don't seem to be moving (?) so I didn't
   look at them.
   
   I'm not volunteering today, but a passing thought I had while browsing
   this complicated code full of scary pointer arithmetic is that it
   might be an idea to try to describe the entire EAN3 number space in a
   much simpler single binary-searchable array that maps uint64_t ranges
   to TO_CHAR format strings, with entries that look something like:
   
    {9780037000000, 9780638999999, "999-9-99-999999-9"}
   

3. Re: ISBN range table

   Florents Tselai <florents.tselai@gmail.com> — 2026-04-14T15:32:47Z

   On Tue, Apr 14, 2026 at 6:05 AM Thomas Munro <thomas.munro@gmail.com> wrote:
   
   > On Sun, Apr 12, 2026 at 11:37 PM Thomas Munro <thomas.munro@gmail.com>
   > wrote:
   > > A recent-ish thread[1] made me wonder what that big table of data
   > > does, and why we have a random update every decade or so, and I came
   > > up with the attached.
   >
   > Fixed a couple of typos and added as commitfest #6676.  The idea is
   > that update_isbn.py would become another periodic update task, similar
   > to Unicode, contrib/unaccent and the IANA timezone stuff.  I suppose
   > running it only for major releases would be enough for such
   > non-critical data.  There are also some other much smaller tables in
   > this contrib module, but they don't seem to be moving (?) so I didn't
   > look at them.
   >
   > I'm not volunteering today, but a passing thought I had while browsing
   > this complicated code full of scary pointer arithmetic is that it
   > might be an idea to try to describe the entire EAN3 number space in a
   > much simpler single binary-searchable array that maps uint64_t ranges
   > to TO_CHAR format strings, with entries that look something like:
   >
   >  {9780037000000, 9780638999999, "999-9-99-999999-9"}
   >
   
    Nitpick; I'd just use standard python and avoid import requests .