I have a Postgresql 10 installation on Ubuntu 18.04 that somehow broke and won't restart. Can I just reinstall it without destroying its databases, so that I can access the databases again? pg_dump doesn't work.
Yes, you can do that.
By default, your databases and other important files are stored in PGDATA.
Traditionally, the configuration and data files used by a database cluster are stored together within the cluster's data directory, commonly referred to as PGDATA (after the name of the environment variable that can be used to define it). A common location for PGDATA is /var/lib/pgsql/data.
https://www.postgresql.org/docs/10/storage-file-layout.html
I don't know how you will uninstall PostgreSQL, but be sure to keep PGDATA.
(yum or apt won't delete PGDATA)
After re-installing PostgreSQL, make sure to launch your PostgreSQL with your existing PGDATA
pg_ctl start -D YOUR_EXISTING_PGDATA/
Related
I would like to switch from postgres 9.6 to version 14 which runs on Ubuntu 21.04. I have a cluster with 3 databases.
I would like to know what is the difference between upgrading with pg_upgrade and pg_upgradecluster? Which one is faster and safer?
pg_upgrade is a tool from Postgresql itself that will operate on a single database (folder).
pg_upgradecluster however is a wrapper from your operating system (= Ubuntu) to pg_upgrade or pg_dump/pg_restore. In addition to very conveniently upgrading your database, it will also do some housekeeping like moving the config files to the correct folder in /etc/postgres/ .
So, if you have set up your database by pg_createcluster and it is hence listed by pg_lsclusters, I'd strongly recommend using pg_upgradecluster to upgrade it.
In terms of "faster vs. safer", be sure to read about the various options on the manpage.
If you can take a reliable backup (e.g. snapshot), you can safely use the -m upgrade --link option which will be fastest and allow for a very short downtime (depending on database size and resources, but I've recently upgraded a 700GB database in ~25 seconds).
The safest option of course is not using pg_upgrade, but the default pg_dump/pg_restore method, which will shut down your original database and copy the data to a new database in a new location (= it will use at approx. twice the space, at least temporarily until you decide to delete the original folder).
I have a kubernetes space where the PostgreSQL DB is on a different POD than the executor where my Typescrtipt code is being executed, which means that I do not have access to pg_dump and psql. Is there a typescript npm library which can backup and restore the DB programmatically and remotely or a special client which I can install in project so that I can use? I could not find such an mpm library or client on the internet.
Another thing that I can think of is some "universal" SQL script, which makes the backup and another one for the restore, if there is such a thing at all.
I have PostgreSQL 9.5 (yes I know it's not supported anymore) installed on Ubuntu Server 18.04 using this instructions https://www.postgresql.org/download/linux/ubuntu/
I want to change path and separate log for every database. But it's configuret by package maintainer in such a way that it ignores log* settings in PostgreSQl configuration and uses some other way to log everything to files and I can't find out how. Currently it logs to /var/log/postgresql/postgresql-9.5-clustername.log. I want it to be /var/log/postgresql/clustername/database.log but I don't know where to configure it. In PostgreSQL log_destination is set to stderr
The Ubuntu packages have logging_collector disabled by default, so the log is not handled by PostgreSQL, but by the startup script.
However, there is no way in PostgreSQL to get a separate log file per database, so the only way to get what you want is to put the databases in individual clusters rather than into a single cluster.
We have a disk on which a Postgres server used to be running, with one important database.
We need to move (and import) one of the databases that were live on that disk, to a live server.
Is that even possible?
I seem to only find scenarios where the server(s) are running when migrating data.
You need to use pg_dump and pg_restore because there is no way in PostgreSQL to copy database files for one single database between 2 instances.
However there is the possibility to copy the old PGDATA to a new PGDATA on new machine
(see How to copy a Postgres database from a mounted disk to a live Postgres server). But you need to have the corresponding PostgreSQL binaries to be able to move the database with pg_dump from old instance to new instance with pg_restore.
I have installed postgres 9.5 in my linux(16.04) machine.I have started service using below command.
sudo service postgresql start
This will start postgres service as a postgres user.
But I want to run postgres a different user(myown user).
How can I do .Please help !!.
You have to recursively change the ownership of the database directory to the new user.
If the WAL directory or tablespaces are outside the data directory, you have to change their ownership too.
Then you will have to configure the startup script so that it starts PostgreSQL as the new user. Watch out: if you installed the startup script with an installation package, any changes to it will probably be lost after an update.
I recommend that you don't do all that and continue running PostgreSQL as postgres.