Thread

1. Upgrading PG11 to PG17 without dump/restore

   Durumdara <durumdara@gmail.com> — 2025-05-01T13:06:22Z

   Hello!
   
   There is a heavily used server, with older debian, and PG11.
   The data is more than 1,2 TB.
   The PG_Upgrade is not possible because of lesser space and too old debian.
   
   As we see now we have only one way to move this server.
   1.) Installing a new server with actual debian.
   2.) Installing the newest PG (17) on it.
   3.) Stop work on one database. Dump it in the old, restore it in the new
   and start the work with that. So we can move them one by one.
   
   But this seems to be very hard, because we need to do this through an
   internet connection, and the data is too much.
   
   I have a question about it - is there a better way to do this?
   
   For example we make a new cluster element (a read only slave) with newest
   debian/PG, and use it to move the data in the background (replication).
   And then we rename it to master. But I don't know if it's possible or not.
   Maybe the slaves must be the same version as the master.
   
   The main problem is that debian is too old, and we are afraid to use
   PG_Upgrade because of too many version differences (11 < 17).
   
   But maybe you have some good advice, how to do this with less complication.
   Users can tolerate short downtimes, but not longer ones.
   
   Thank you!
   
   Best regards
   dd
   

2. Re: Upgrading PG11 to PG17 without dump/restore

   Ron <ronljohnsonjr@gmail.com> — 2025-05-01T13:19:25Z

   On Thu, May 1, 2025 at 9:06 AM Durumdara <durumdara@gmail.com> wrote:
   
   > Hello!
   >
   > There is a heavily used server, with older debian, and PG11.
   > The data is more than 1,2 TB.
   > The PG_Upgrade is not possible because of lesser space and too old debian.
   >
   > As we see now we have only one way to move this server.
   > 1.) Installing a new server with actual debian.
   > 2.) Installing the newest PG (17) on it.
   > 3.) Stop work on one database. Dump it in the old, restore it in the new
   > and start the work with that. So we can move them one by one.
   >
   > But this seems to be very hard, because we need to do this through an
   > internet connection, and the data is too much.
   >
   
   The new server isn't in the same data center?
   
   
   > I have a question about it - is there a better way to do this?
   >
   > For example we make a new cluster element (a read only slave) with newest
   > debian/PG, and use it to move the data in the background (replication).
   > And then we rename it to master. But I don't know if it's possible or not.
   > Maybe the slaves must be the same version as the master.
   >
   > The main problem is that debian is too old, and we are afraid to use
   > PG_Upgrade because of too many version differences (11 < 17).
   >
   
   The fear is justified, since collation changes might corrupt text indices.
   
   
   > But maybe you have some good advice, how to do this with less complication.
   > Users can tolerate short downtimes, but not longer ones.
   >
   
   Logical replication, not physical replication.  Works great if there's not
   many DDL changes.
   
   Another possibility is COPY TO / COPY FROM in chunks.  This will work if
   most of the 1.2TB is inserted, and then never updated or deleted.  That
   way, at cutover, you only need to COPY TO / COPY FROM and dump/restore
   (which is really a wrapper around COPY TO / COPY FROM) and "pg_restore
   --section=post-data".
   
   You (hopefully) know your system better than we do, so you'd have to decide
   which is better.
   
   -- 
   Death to <Redacted>, and butter sauce.
   Don't boil me, I'm still alive.
   <Redacted> lobster!
   

3. Re: Upgrading PG11 to PG17 without dump/restore

   Adrian Klaver <adrian.klaver@aklaver.com> — 2025-05-01T15:25:25Z

   On 5/1/25 06:06, Durumdara wrote:
   > Hello!
   > 
   > There is a heavily used server, with older debian, and PG11.
   > The data is more than 1,2 TB.
   > The PG_Upgrade is not possible because of lesser space and too old debian.
   
   1) Specify what the old and new versions of Debian are.
   
   2) I don't understand what the following means: "The PG_Upgrade is not 
   possible because of lesser space ..." .
   
   
   > But this seems to be very hard, because we need to do this through an 
   > internet connection, and the data is too much.
   
   An Internet connection can be dial up speed or direct fiber speed, you 
   will need to be more specific about the connection capabilities.
   
   
   > Best regards
   > dd
   > 
   
   -- 
   Adrian Klaver
   adrian.klaver@aklaver.com
   
   
   
   
   

4. Re: Upgrading PG11 to PG17 without dump/restore

   Justin Clift <justin@postgresql.org> — 2025-05-01T22:27:30Z

   On 2025-05-01 23:06, Durumdara wrote:
   <snip>
   > The PG_Upgrade is not possible because of lesser space and too old 
   > debian.
   
   As a data point, pg_upgrade has an option to do an in-place upgrade 
   which
   reuses the vast majority of the data files as they are on disk, rather 
   than
   making a copy.
   
   It's useful for larger databases, and for situations where you don't 
   have
   much space.
   
   BUT, you *do* have backups don't you?
   
   Because stuff *can* go wrong, even though it's not common. ;)
   
   Regards and best wishes,
   
   Justin Clift