when I go to the site http://archive.raspbian.org/raspbian/pool/main/p/ I clearly see the directory postgresql-10.
The repo likely contains packages from the testing branch (v.10, Buster).
Sometimes it is feasible to install them manually, but it can get pretty tedious (so you might want to try a source build instead first). First:
That's because the package will open up without a tidy toplevel of its own.
ar x postgresql-10_10.3-2_armhf.deb
This leaves a couple of
tar -xJf control.tar.xz
tar -xJf data.tar.xz
The first one contains a some meta information in text files;
control will include a
Depends: list which you will need to consider.
The second one will open up into a directory tree rooted at
usr in the current directory. If you actually install it, those files are distributed in the root filesystem (i.e.,
You can run
ldd on the binaries to see if the system can provide the shared libraries to run. I did not go that far (I don't have anything at hand running Raspbian), but there's a daunting number of shared object in that package, and the service files that are used to control the server (
/lib/systemd/system/postgresql.service) must be in some other package...