Migrating Postgres server from Windows to Linux

Question

Simple question: I want to migrate all of a Postgres server's data, schema, roles, everything from Windows to Linux.

Can I just copy the contents of the %PGDATA% directory in Windows to which the server points to Linux and start the server there pointing PGDATA argument/variable to that directory? In other words, are the data files platform independent to make porting from one OS to another a matter of copying?

I also have developed a script for cloning PG databases, schema+data but, for a variety of reasons, I would prefer to just put the data files on a USB drive and be done with it.

Answer 1

No, you cannot do that. The files in the data directory are not compatible across operating systems (or different architectures).

You will need to use pg_dump and pg_restore

Answer 2

Just for the record, you should ask in PostgreSQL mailing list.

My personal idea is the binary format is fixed, so no problem.

Anyway, just to try, I:

a) copy the pgdata directory, from PG9.5 from Windows Server 2012 to Linux;

b) compile 9.5 on Linux;

c) change the specific Windows options in postgresql.conf;

d) run it...

And it starts, but it complains about locale (I have to investigate further to figure out):

LOG: database system was interrupted; last known up at 2020-02-27 03:57:27 CET

LOG: database system was not properly shut down; automatic recovery in progress

LOG: redo starts at 34/DFD49EF8

LOG: invalid record length at 34/DFE33560

LOG: redo done at 34/DFE33538

LOG: last completed transaction was at log time 2020-02-27 04:00:52.844739+01

LOG: MultiXact member wraparound protections are now enabled

LOG: database system is ready to accept connections

LOG: autovacuum launcher started

FATAL: no pg_hba.conf entry for host "[local]", user "gelma", database "postgres"

FATAL: no pg_hba.conf entry for host "[local]", user "gelma", database "postgres"

FATAL: no pg_hba.conf entry for host "[local]", user "gelma", database "template1"

FATAL: no pg_hba.conf entry for host "[local]", user "gelma", database "template0"

FATAL: role "gelma" does not exist

FATAL: database locale is incompatible with operating system

DETAIL: The database was initialized with LC_COLLATE "Italian_Italy.1252", which is not recognized by setlocale().

HINT: Recreate the database with another locale or install the missing locale.

FATAL: database locale is incompatible with operating system

DETAIL: The database was initialized with LC_COLLATE "Italian_Italy.1252", which is not recognized by setlocale().

Anyway the server is up and running. Also using pg_dump I don't think the locale is automagically converted.

So, finding the original super user and how to change collate/locale should be the only things left.