Restore postgres db from folder - postgresql

Question

i have an old copy of my postgresql db folder (/var/lib/postgresql/9.5/main/) from my server. Now I want to get the data out of the files. So i copied the main folder to my local machine and changed the postgresql config (/etc/postgresql/9.5/main/postgresql.conf) to point to that directory. Also i changed the permission of the main directory to the user postgres. After restarting the postgresql service (sudo service postgresql restart) it doesn't really work.
What I'm doing wrong? (Yea I know, pg_dump is the preferred way, but in this way...)
So my question, does this even work?
Or is there a other way to get the data out of this?
everything is done on ubuntu 16.04.
Edit:
the log file after changing the postgresql.conf file to point to the new directory.
2017-10-13 06:15:43 CEST [968-1] LOG: database system was shut down at 2017-10-13 00:21:04 CEST
2017-10-13 06:15:43 CEST [968-2] LOG: MultiXact member wraparound protections are now enabled
2017-10-13 06:15:43 CEST [959-1] LOG: database system is ready to accept connections
2017-10-13 06:15:43 CEST [975-1] LOG: autovacuum launcher started
2017-10-13 06:15:43 CEST [983-1] [unknown]#[unknown] LOG: incomplete startup packet
2017-10-13 06:47:55 CEST [975-2] LOG: autovacuum launcher shutting down
2017-10-13 06:47:55 CEST [959-2] LOG: received smart shutdown request
2017-10-13 06:47:55 CEST [972-1] LOG: shutting down
2017-10-13 06:47:55 CEST [972-2] LOG: database system is shut down
2017-10-13 06:47:55 CEST [4667-1] FATAL: database files are incompatible with server
2017-10-13 06:47:55 CEST [4667-2] DETAIL: The database cluster was initialized without USE_FLOAT8_BYVAL but the server was compiled with USE_FLOAT8_BYVAL.
2017-10-13 06:47:55 CEST [4667-3] HINT: It looks like you need to recompile or initdb.
Ok that pointed me to this. The server is a armv7l, whereas the local machine is x86_64 (uname -m). So there is no chance to get the data out of it?
thx, Luc

Answer 1

If it's really true that your data directory is from an ARM7l system, and your local system is x86_64, you're going to have some difficulties.
The immediate error about USE_FLOAT8_BYVAL is because ARM7L is 32-bit, and cannot pass 64-bit floating point values (8 byte) by-value. Your 64-bit host can. But if you recompiled a custom postgres with USE_FLOAT8_BYVAL disabled you'd likely just run into other issues.
I suggest installing PostgreSQL on a matching ARM system to recover the data. Data directories for PostgreSQL are not portable across architectures (for performance reasons).
If you do not have access to the ARM system anymore, an emulator like qemu should be able to help you.
Otherwise, maybe you can compile a modified PostgreSQL (probably starting with 32-bit x86) that can read the data-dir, with appropriate configure options etc. I've never needed to try this.