postgresql-common

09:01 <za1b1tsu> Is it possible to have a shared database on a common partition between 2 OSes? Because I'm trying to achieve this and I can't start the postgres service after changing the data_directory to the shared one.
09:01 <za1b1tsu> It's version 9.6.10
09:02 <RhodiumToad> 2 OSes that you are dual-booting? i.e. only one is running at a time?
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09:02 <RhodiumToad> the answer is that it depends on the OSes
09:03 <peerce> if their libc implementations different significantly, it may not work.
09:03 <za1b1tsu> yes dual booting, one is Mac on is Linux, but right now I'm testing this on the VM. Sice I don't want to setup everything and then realize it doesnt work and have to start other.
09:04 <peerce> what error do you get when you try and start the 'other' OS that didn't create this ?
09:04 <za1b1tsu> the problem is the postgresql log in /var/log/... does not say much or I don't know how to interpret
09:04 <RhodiumToad> mac vs linux likely won't work unless you use C locale everywhere in the db - other locales will be incompatible
09:04 <peerce> often a different startup log gets created
09:05 <RhodiumToad> what does the log say?
09:05 <peerce> which OS created the database file system ?
09:05 <za1b1tsu> https://gist.github.com/bbtdev/a0207b508d8741702daa4a6b08642842
09:05 <za1b1tsu> I don't think it logs the start sequence?
09:06 <RhodiumToad> yes it does
09:06 <za1b1tsu> The database was create on MacOSX
09:06 <peerce> anbd what flavor of linux is trying to start it ?
09:06 <RhodiumToad> and you're currently booted into linux and trying to start it? what linux distro?
09:06 <za1b1tsu> Ubuntu 18.10 in a VM
09:06 <za1b1tsu> Mojave bare-metal
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09:07 <RhodiumToad> and pg_lsclusters shows what?
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09:07 <za1b1tsu> RhodiumToad: Ver Cluster Port Status Owner Data directory Log file
09:08 <RhodiumToad> how exactly were you trying to start pg?
09:08 <za1b1tsu> sudo service postgresql start
09:08 <za1b1tsu> I change back the data_dir it works
09:08 <RhodiumToad> where did you change it exactly?
09:09 <za1b1tsu> postgresql.conf and sudo -su postgres
09:09 <za1b1tsu> *as
09:09 <RhodiumToad> which postgresql.conf
09:09 <za1b1tsu> wait, maybe I need to shut it down on my Mac?
09:09 <peerce> oh, absolutely you have to shut it down
09:09 <za1b1tsu> /etc/postgresql/9.6/main/postgresql.conf 
09:09 <peerce> but it should have complained it was already in use
09:09 <RhodiumToad> uh, you can't have two instances running in the same data directory at once, if you try that hilarity will ensue
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09:10 <RhodiumToad> most likely you were saved from disaster by the new data dir not being accessible to the linux postgres user
09:10 <peerce> also, how is the VM mounting the macos data directory ?
09:10 <za1b1tsu> it's not working, stopped on macos, tried to start on ubuntu
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09:11 <za1b1tsu> peerce: it's through vagrant shared folder
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09:11 <peerce> how does that handle user mappings?   like, what user is postgres running as on macosx, who owns the files?
09:11 <peerce> is the linux vm using the same UID/GID for its postgres account ?
09:13 <za1b1tsu> ah, the files on the Mac are owned by 'bogdan', should I change the owner to postgres?
09:13 <za1b1tsu> UID/GID I don't know how to do this
09:14 <RhodiumToad> I think you should probably give up the idea
09:14 <RhodiumToad> do you have a good reason to want to do this?
09:14 <peerce> in linux, ls -n /path/to/mapped/data
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09:14 <RhodiumToad> I already pointed out that you'll have locale problems - by which I mean, unless you use C locale for all your databases and never override it, you'll get rampant index corruption
09:14 <peerce> yeah, the OS X C compiler and libc is just way different than gcc/glibc
09:15 <za1b1tsu> RhodiumToad: effiency, 265 ssd only. But I could live without it.
09:15 <za1b1tsu> it was a nice experiment
09:15 <za1b1tsu> but way above my technicall abilities
09:15 <peerce> dual booting IMHO sucks, run the 'other' OS as a VM, and have it connect to the host OS postgres server
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09:15 <RhodiumToad> yeah, it's much easier to have the server running on one OS and connecting to it from the other one
09:16 <peerce> if the host OS is mac osx, configure it so the linux VM can connect to it
09:16 <peerce> then you can run postgres apps on linux which connect to the osx db server
09:17 <za1b1tsu> hmmm
09:18 <za1b1tsu> or I could run a postgresql server in a VM?
09:19 <za1b1tsu> and connect to it from the host
09:19 <peerce> yes,  you could do that alternately, but then the VM would have to be running to access it from the host OS
09:19 <za1b1tsu> I could use something really light, like alpine linux
09:19 <peerce> if you're using it for sw devleopment or whatever, that may not be terribly convenient unless you keep the VM always on, eating resources
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09:21 <za1b1tsu> anyway, thank you so much for the help and interest
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