Backstory: I had a debian 11 VPS. I installed the postgresql program from the debian 11 apt repo, back a few months ago. Back then, it was postgres 13 on the debian stable repos.

Fast forward couple months: debian 12 comes out. I do a “apt dist-upgrade” and in-place upgrade my VPS from debian 11 to debian 12. Along with this upgrade, comes postgresql 15 installed.

Now, fast forward couple more months: lemmy 0.18.3 comes out. I do not upgrade (I am on lemmy 0.18.2—afaik).

Fast forward some time, too: lemmy 0.18.4 comes out. I decide to upgrade to 0.18.4 from my existing 0.18.2.

I pull the git repo. Compile it locally. It goes well, no errors in the compilation process. I stop the lemmy systemd service, then I “mv” the compiled “lemmy_server” to /usr/bin dir.

I try to restart the now-upgraded lemmy systemd service. However, the systemd service fails.

I check the sudo journalctl -fu lemmy and I see the following error message:

lemmy_server[17631]: thread 'main' panicked at 'Couldn't run DB Migrations: Failed to run 2023-07-08-101154_fix_soft_delete_aggregates with: syntax error at or near "trigger"', crates/db_schema/src/utils.rs:221:25

I report this issue here: https://github.com/LemmyNet/lemmy/issues/3756#issuecomment-1686439103

However, after a few back and forths and internet search, I conclude that somewhere between lemmy 0.18.3 and 0.18.4, lemmy stops supporting psql <15. So, my existing DB is not compatible.

Upon my investigation on my VPS setup, I concluded that psql 15 is running, however, lemmy is using the psql 13 tables (I do not know if this is the correct term).

Now my question: is there a way to import the lemmy data I had in the psql 13 tables to a new psql 15 table (or database, I don’t know the term).

To make things hairier: I also run a dendrite server on the same VPS, and the dendrite server is using the psql 15 with psql 13 tables on the same database as the lemmy one.

The dendrite database is controlled by a psql user named “dendrite” and the lemmy database is controlled by a psql user named “lemmy” . I hope this makes differentiation between two databases possible. And so I do not harm my existing dendrite database.

Any recommendations about my options here?

    • Anark KarabeyOP
      2·
      1 year ago
      user@server:~$ grep --after-context=6 "\-- Database" lemmy_databackup_2.sql
-- Databases
--

--
-- Database "template1" dump
--

\connect template1

--
-- PostgreSQL database dump
--
-- Database "lemmy" dump
--

--
-- PostgreSQL database dump
--

--
-- Database "postgres" dump
--

\connect postgres

--
-- PostgreSQL database dump
user@server:~$
      • RoundSparrow @ BT@bulletintree.comM
        1·
        1 year ago

        Ok, i came up with a useful grep, do you get two results and what can you describe as different between them?

        grep --after-context=6 "Data for Name: site; Type: TABLE DATA;" lemmy_databackup_2.sql

        • Anark KarabeyOP
          1·
          1 year ago

          do you get two results and what can you describe as different between them?

          Holy shit I get screen-ful of results. I can’t even say which result end where and the next one starts where.

          EDIT: After zoom-ing out the terminal, I think I get 2 results. They both seem to be listing the different lemmy servers my own lemmy has ever connected with, or federated with. Not sure.

          • RoundSparrow @ BT@bulletintree.comM
            2·
            1 year ago

            Ok, so what you are looking for is up to this point, especially the line starting with '1"

            COPY public.site (id, name, sidebar, published, updated, icon, banner, description, actor_id, last_refreshed_at, inbox_url, private_key, public_key, instance_id) FROM stdin;
1	lemmy-gamma	\N	2023-08-16 21:42:52.88018	2023-08-16 21:47:45.32338	\N	\N	\N	http://lemmy-gamma:8561/	2023-08-16 21:42:52.877719http://lemmy-gamma:8561/site_inbox	-----BEGIN PRIVATE KEY-----\n
            • Anark KarabeyOP
              1·
              1 year ago

              I got only one instance of COPY public.site [...] followed by a line starting with '1".

              • RoundSparrow @ BT@bulletintree.comM
                2·
                1 year ago

                Going back to the output you got… line one, what are the dates you see?

                COPY public.site (id, name, sidebar, published, updated, icon, banner, description, actor_id, last_refreshed_at, inbox_url, private_key, public_key, instance_id) FROM stdin;
1	lemmy-gamma	\N	2023-08-16 21:42:52.88018	2023-08-16 21:47:45.32338
                • Anark KarabeyOP
                  2·
                  1 year ago
                  1       New Site        \N      2023-08-22 22:38:51.37196       \N      \N      \N      \N      https://domain.tld/   2023-08-22 22:38:51.364569    h
ttps://domain.tld/site_inbox

                  domain.tld is my instance’s domain name which I have redacted.

                  and then it lists my instance’s private key.