Postgresql: How to apply pg_dump --exclude-table-data patch?

Postgresql: How to apply pg_dump --exclude-table-data patch? - database

I have a production server (ec2) with a Django App and Postgresql Database.
I make a DB backup everynight with pg_dump which backs up the tables data.
sudo -u postgres pg_dump --column-inserts --data-only mydb > mybackup.sql
Postgres provides the possibility of ignoring some tables to be backed up (tables schema + data: --exclude-table=TABLE)
However I have some tables, that I would like backup their schema but not their data, I just want to dump the table with empty data, the old data are not important at all, but they make the backup file huge if dumped.
There is a patch "exclude-table-data=TABLE" that allows a user to have pg_dump
exclude data but not DDL for a table. One use case for this is a very
large table that changes infrequently, and for which dumping data
frequently would be wasteful and unnecessary.
I would like to know how to apply this patch without losing anything on my database on my production server.

exclude-table-data is now a regular option of pg_dump from PostgreSQL 9.2+, so if your server is a recent version, it is already available (see documentation page: http://www.postgresql.org/docs/9.2/static/app-pgdump.html)

I found a better solution, upgrade PostgreSQL to a version 9.2 or higher, and I found a safe way to do so: (Upgrade PostgreSQL 9.1 to 9.3 on Ubuntu 12.04)
echo "deb http://apt.postgresql.org/pub/repos/apt/ precise-pgdg main" | sudo tee /etc/apt/sources.list.d/pgdg.list
wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -
sudo apt-get update
sudo apt-get install postgresql-9.3 postgresql-server-dev-9.3 postgresql-contrib-9.3 -y
sudo su - postgres -c "psql template1 -p 5433 -c 'CREATE EXTENSION IF NOT EXISTS hstore;'"
sudo su - postgres -c "psql template1 -p 5433 -c 'CREATE EXTENSION IF NOT EXISTS \"uuid-ossp\";'"
sudo su - postgres -c "service postgresql stop"
sudo su - postgres -c '/usr/lib/postgresql/9.3/bin/pg_upgrade -b /usr/lib/postgresql/9.1/bin -B /usr/lib/postgresql/9.3/bin -d /var/lib/postgresql/9.1/main/ -D /var/lib/postgresql/9.3/main/ -O "-c config_file=/etc/postgresql/9.3/main/postgresql.conf" -o "-c config_file=/etc/postgresql/9.1/main/postgresql.conf"'
sudo apt-get remove postgresql-9.1 -y
sudo sed -i "s:5433:5432:g" /etc/postgresql/9.3/main/postgresql.conf
sudo service postgresql restart
Note: This will install both PostgreSQL 9.3 and 9.4, so whether remove PostgreSQL 9.4 when finished or change the above code to upgrade to version 9.4.
Reference.
Later I realized that, since I'm using --data-only, --exclude-table and --exclude-table-data would have the same effect since I'm ignoring the schema !

Related

PostgreSQL installation failed on Ubuntu 14.04

I recently uninstalled postgresql from my computer. I tried to install it again but I faced some problems. I tried to fully uninstall it again like this:
I found al the packages related to postgres:
$ dpkg -l | grep postgres
Them I removed all the packages and related folders :
$ sudo apt-get --purge remove postgresql postgresql-9.3 postgresql-client-9.3 postgresql-client-common postgresql-common postgresql-contrib-9.3
$ sudo rm -rf /var/lib/postgresql/
$ sudo rm -rf /var/log/postgresql/
$ sudo rm -rf /etc/postgresql/
I've tried to install it again, but after the installation I can't access postgres user.
$ sudo apt-get install postgresql postgresql-contrib
$ sudo -i -u postgres
sudo: unable to change directory to /home/postgres: No such file or directory
If I access root I can access postgres but this is what happens:
$ sudo su -
$ su - postgres
No directory, logging in with HOME=/
postgres#rafael-pc:/$ psql
psql (9.3.9)
Type "help" for help.
postgres=# \q
could not save history to file "/home/postgres/.psql_history": No such file or directory
I have no idea what is happening. I've tried to uninstall it many times but I always have some kind of error when I install it back.

Just a guess here, but it sure looks to me like the problem is that there isn't a /home/postgres directory. I'm not sure what may have happened in your uninstall process to remove that, but it looks like that's the cause of the error in both of the steps you list.
Can you try this (or some approximation of these steps, which create that directory and make sure it's owned by the postgres user)?
# sudo mkdir /home/postgres
# sudo chown postgres /home/postgres

Starting and populating a Postgres container in Docker

I have a Docker container that contains my Postgres database. It's using the official Postgres image which has a CMD entry that starts the server on the main thread.
I want to populate the database by running RUN psql –U postgres postgres < /dump/dump.sql before it starts listening to queries.
I don't understand how this is possible with Docker. If I place the RUN command after CMD, it will of course never be reached because Docker has finished reading the Dockerfile. But if I place it before the CMD, it will run before psql even exists as a process.
How can I prepopulate a Postgres database in Docker?

After a lot of fighting, I have found a solution ;-)
For me was very useful a comment posted here: https://registry.hub.docker.com/_/postgres/ from "justfalter"
Anyway, I have done in this way:
# Dockerfile
FROM postgres:9.4
RUN mkdir -p /tmp/psql_data/
COPY db/structure.sql /tmp/psql_data/
COPY scripts/init_docker_postgres.sh /docker-entrypoint-initdb.d/
db/structure.sql is a sql dump, useful to initialize the first tablespace.
Then, the init_docker_postgres.sh
#!/bin/bash
# this script is run when the docker container is built
# it imports the base database structure and create the database for the tests
DATABASE_NAME="db_name"
DB_DUMP_LOCATION="/tmp/psql_data/structure.sql"
echo "*** CREATING DATABASE ***"
# create default database
gosu postgres postgres --single <<EOSQL
CREATE DATABASE "$DATABASE_NAME";
GRANT ALL PRIVILEGES ON DATABASE "$DATABASE_NAME" TO postgres;
EOSQL
# clean sql_dump - because I want to have a one-line command
# remove indentation
sed "s/^[ \t]*//" -i "$DB_DUMP_LOCATION"
# remove comments
sed '/^--/ d' -i "$DB_DUMP_LOCATION"
# remove new lines
sed ':a;N;$!ba;s/\n/ /g' -i "$DB_DUMP_LOCATION"
# remove other spaces
sed 's/ */ /g' -i "$DB_DUMP_LOCATION"
# remove firsts line spaces
sed 's/^ *//' -i "$DB_DUMP_LOCATION"
# append new line at the end (suggested by #Nicola Ferraro)
sed -e '$a\' -i "$DB_DUMP_LOCATION"
# import sql_dump
gosu postgres postgres --single "$DATABASE_NAME" < "$DB_DUMP_LOCATION";
echo "*** DATABASE CREATED! ***"
So finally:
# no postgres is running
[myserver]# psql -h 127.0.0.1 -U postgres
psql: could not connect to server: Connection refused
Is the server running on host "127.0.0.1" and accepting
TCP/IP connections on port 5432?
[myserver]# docker build -t custom_psql .
[myserver]# docker run -d --name custom_psql_running -p 5432:5432 custom_psql
[myserver]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ce4212697372 custom_psql:latest "/docker-entrypoint. 9 minutes ago Up 9 minutes 0.0.0.0:5432->5432/tcp custom_psql_running
[myserver]# psql -h 127.0.0.1 -U postgres
psql (9.2.10, server 9.4.1)
WARNING: psql version 9.2, server version 9.4.
Some psql features might not work.
Type "help" for help.
postgres=#
# postgres is now initialized with the dump
Hope it helps!

For those who want to initialize a PostgreSQL DB with millions of records during the first run.
Import using *.sql dump
You can do simple sql dump and copy the dump.sql file into /docker-entrypoint-initdb.d/. The problem is speed. My dump.sql script is about 17MB (small DB - 10 tables with 100k rows in only one of them) and the initialization takes over a minute (!). That is unacceptable for local development / unit test, etc.
Import using binary dump
The solution is to make a binary PostgreSQL dump and use shell scripts initialization support.
Then the same DB is initialized in about 500ms instead of 1 minute.
1. Create the dump.pgdata binary dump of a DB named "my-db"
directly from within a container or your local DB
pg_dump -U postgres --format custom my-db > "dump.pgdata"
Or from host from running container (postgres-container)
docker exec postgres-container pg_dump -U postgres --format custom my-db > "dump.pgdata"
2. Create a Docker image with a given dump and initialization script
$ tree
.
├── Dockerfile
└── docker-entrypoint-initdb.d
├── 01-restore.sh
├── 02-small-updates.sql
└── dump.pgdata
$ cat Dockerfile
FROM postgres:11
COPY ./docker-entrypoint-initdb.d/ /docker-entrypoint-initdb.d/
$ cat docker-entrypoint-initdb.d/01-restore.sh
#!/bin/bash
file="/docker-entrypoint-initdb.d/dump.pgdata"
dbname=my-db
echo "Restoring DB using $file"
pg_restore -U postgres --dbname=$dbname --verbose --single-transaction < "$file" || exit 1
$ cat docker-entrypoint-initdb.d/02-small-updates.sql
-- some updates on your DB, for example for next application version
-- this file will be executed on DB during next release
UPDATE ... ;
3. Build an image and run it
$ docker build -t db-test-img .
$ docker run -it --rm --name db-test db-test-img

Alternatively, you can just mount a volume to /docker-entrypoint-initdb.d/ that contains all your DDL scripts. You can put in *.sh, *.sql, or *.sql.gz files and it will take care of executing those on start-up.
e.g. (assuming you have your scripts in /tmp/my_scripts)
docker run -v /tmp/my_scripts:/docker-entrypoint-initdb.d postgres

There is yet another option available that utilises Flocker:
Flocker is a container data volume manager that is designed to allow databases like PostgreSQL to easily run in containers in production. When running a database in production, you have to think about things like recovering from host failure. Flocker provides tools for managing data volumes across a cluster of machines like you have in a production environment. For example, as a Postgres container is scheduled between hosts in response to server failure, Flocker can automatically move its associated data volume between hosts at the same time. This means that when your Postgres container starts up on a new host, it has its data. This operation can be accomplished manually using the Flocker API or CLI, or automatically by a container orchestration tool that Flocker is integrates with, for example Docker Swarm, Kubernetes or Mesos.

I Followed the same solution which #damoiser , The only situation which was different was I wanted to import all dump data.
Please follow the solution below.(I have not done any kind of checks)
Dockerfile
FROM postgres:9.5
RUN mkdir -p /tmp/psql_data/
COPY db/structure.sql /tmp/psql_data/
COPY scripts/init_docker_postgres.sh /docker-entrypoint-initdb.d/
then the init_docker_postgres.sh script
#!/bin/bash
DB_DUMP_LOCATION="/tmp/psql_data/structure.sql"
echo "*** CREATING DATABASE ***"
psql -U postgres < "$DB_DUMP_LOCATION";
echo "*** DATABASE CREATED! ***"
and then you can build your image as
docker build -t abhije***/postgres-data .
docker run -d abhije***/postgres-data

My solution is inspired by Alex Dguez's answer which unfortunately doesn't work for me because:
I used pg-9.6 base image, and the RUN /docker-entrypoint.sh --help never ran through for me, which always complained with The command '/bin/sh -c /docker-entrypoint.sh -' returned a non-zero code: 1
I don't want to pollute the /docker-entrypoint-initdb.d dir
The following answer is originally from my reply in another post: https://stackoverflow.com/a/59303962/4440427. It should be noted that the solution is for restoring from a binary dump instead of from a plain SQL as asked by the OP. But it can be modified slightly to adapt to the plain SQL case
Dockerfile:
FROM postgres:9.6.16-alpine
LABEL maintainer="lu#cobrainer.com"
LABEL org="Cobrainer GmbH"
ARG PG_POSTGRES_PWD=postgres
ARG DBUSER=someuser
ARG DBUSER_PWD=P#ssw0rd
ARG DBNAME=sampledb
ARG DB_DUMP_FILE=example.pg
ENV POSTGRES_DB launchpad
ENV POSTGRES_USER postgres
ENV POSTGRES_PASSWORD ${PG_POSTGRES_PWD}
ENV PGDATA /pgdata
COPY wait-for-pg-isready.sh /tmp/wait-for-pg-isready.sh
COPY ${DB_DUMP_FILE} /tmp/pgdump.pg
RUN set -e && \
nohup bash -c "docker-entrypoint.sh postgres &" && \
/tmp/wait-for-pg-isready.sh && \
psql -U postgres -c "CREATE USER ${DBUSER} WITH SUPERUSER CREATEDB CREATEROLE ENCRYPTED PASSWORD '${DBUSER_PWD}';" && \
psql -U ${DBUSER} -d ${POSTGRES_DB} -c "CREATE DATABASE ${DBNAME} TEMPLATE template0;" && \
pg_restore -v --no-owner --role=${DBUSER} --exit-on-error -U ${DBUSER} -d ${DBNAME} /tmp/pgdump.pg && \
psql -U postgres -c "ALTER USER ${DBUSER} WITH NOSUPERUSER;" && \
rm -rf /tmp/pgdump.pg
HEALTHCHECK --interval=30s --timeout=30s --start-period=5s --retries=3 \
CMD pg_isready -U postgres -d launchpad
where the wait-for-pg-isready.sh is:
#!/bin/bash
set -e
get_non_lo_ip() {
local _ip _non_lo_ip _line _nl=$'\n'
while IFS=$': \t' read -a _line ;do
[ -z "${_line%inet}" ] &&
_ip=${_line[${#_line[1]}>4?1:2]} &&
[ "${_ip#127.0.0.1}" ] && _non_lo_ip=$_ip
done< <(LANG=C /sbin/ifconfig)
printf ${1+-v} $1 "%s${_nl:0:$[${#1}>0?0:1]}" $_non_lo_ip
}
get_non_lo_ip NON_LO_IP
until pg_isready -h $NON_LO_IP -U "postgres" -d "launchpad"; do
>&2 echo "Postgres is not ready - sleeping..."
sleep 4
done
>&2 echo "Postgres is up - you can execute commands now"
The above scripts together with a more detailed README are available at https://github.com/cobrainer/pg-docker-with-restored-db

I was able to load the data in by pre-pending the run command in the docker file with /etc/init.d/postgresql. My docker file has the following line which is working for me:
RUN /etc/init.d/postgresql start && /usr/bin/psql -a < /tmp/dump.sql

We for E2E test in which we need a database with structure and data already saved in the Docker image we have done the following:
Dockerfile:
FROM postgres:9.4.24-alpine
ENV POSTGRES_USER postgres
ENV POSTGRES_PASSWORD postgres
ENV PGDATA /pgdata
COPY database.backup /tmp/
COPY database_restore.sh /docker-entrypoint-initdb.d/
RUN /docker-entrypoint.sh --help
RUN rm -rf /docker-entrypoint-initdb.d/database_restore.sh
RUN rm -rf /tmp/database.backup
database_restore.sh:
#!/bin/sh
set -e
pg_restore -C -d postgres /tmp/database.backup
To create the image:
docker build .
To start the container:
docker run --name docker-postgres -d -p 5432:5432 <Id-docker-image>
This does not restore the database every time the container is booted. The structure and data of the database is already contained in the created Docker image.
We have based on this article, but eliminating the multistage:
Creating Fast, Lightweight Testing Databases in Docker
Edit: With version 9.4-alpine does not work now because it does not
run the database_restore.sh scrips. Use version 9.4.24-alpine

My goal was to have an image that contains the database - i. e. saving the time to rebuild it everytime I do docker run oder docker-compose up.
We would just have to manage to get the line exec "$#" out of docker-entrypoint.sh. So I added into my Dockerfile:
#Copy my ssql scripts into the image to /docker-entrypoint-initdb.d:
COPY ./init_db /docker-entrypoint-initdb.d
#init db
RUN grep -v 'exec "$#"' /usr/local/bin/docker-entrypoint.sh > /tmp/docker-entrypoint-without-serverstart.sh && \
chmod a+x /tmp/docker-entrypoint-without-serverstart.sh && \
/tmp/docker-entrypoint-without-serverstart.sh postgres && \
rm -rf /docker-entrypoint-initdb.d/* /tmp/docker-entrypoint-without-serverstart.sh

How do I install/update to Postgres 9.4?

I just installeed Postgres, but it seems to have installed 9.3 and I'd like to start with 9.4
I simply did apt-get install postgresql from a new Ubuntu 14.04.1 machine.
http://www.postgresql.org/download/linux/ubuntu/
says you can do:
apt-get install postgresql-9.4
but when I try that I get:
E: Couldn't find any package by regex 'postgresql-9.4
Okay, so I try the section below where you add the PostgreSQL Apt Repository but that can't find anything either.
Is 9.4 not in the package managers yet? Am I doing something horribly wrong?

You can add it from the instructions in the page
http://www.postgresql.org/download/linux/ubuntu/
Create the file /etc/apt/sources.list.d/pgdg.list, and add a line for the repository
deb http://apt.postgresql.org/pub/repos/apt/ trusty-pgdg main
Import the repository signing key, and update the package lists
wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -
sudo apt-get update && sudo apt-get install postgresql-9.4

postgresql-9.4 is not available in 14.04 "Trusty". It was added in 14.10 "Utopic". It may be back ported in the future.
The directions on the PostgreSQL Ubuntu Download page are missing a command. Their wiki guide has the correct procedure. You must run apt-get update before trying to install. This will cause the system to read changes to the sources.

If you're trying to install on Ubuntu 14.04 "Trusty", you can follow these steps:
To check your version:
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 14.04.3 LTS
Release: 14.04
Codename: trusty
1) Create new apt repo file for postgres
$ echo "deb http://apt.postgresql.org/pub/repos/apt/ trusty-pgdg main" > /etc/apt/sources.list.d/pgdg.list
2) Import repository signing key and update packages list
$ sudo wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -
$ sudo apt-get update
3) Install Postgres
$ sudo apt-get install postgresql-9.4
credit: http://ubuntuhandbook.org/index.php/2014/02/install-postgresql-ubuntu-14-04/

Below are steps to install PostgreSQL 9.4 on Ubuntu 14.04.
Reference taken from this Article:
First, check the version of Ubuntu:
lsb_release -sc
You need to add the latest PostgreSQL repository for the latest version, otherwise It will install PostgreSQL 9.3. This is for trusty version.
sudo add-apt-repository "deb https://apt.postgresql.org/pub/repos/apt/ trusty-pgdg main"
Update and Install PostgreSQL 9.4:
sudo apt-get update
sudo apt-get install postgresql-9.4
Default postgres super user and postgres database is created. You need to set a password for the postgres super user.
ubuntu#:~$ sudo passwd postgres
Enter new UNIX password:****
Retype new UNIX password:****
passwd: password updated successfully
If service is not started, you can start the PostgreSQL service.
sudo service postgresql start
Connect PostgreSQL server using postgres user:
ubuntu#:~$ su postgres
Password:****
Create a sample database:
createdb database_name
Connect to that database:
psql -d database_name

Follow these steps to install postgresql. Open the terminal (Ctrl + Alt + t) and then write down the following command line
sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt/ `lsb_release -cs`-pgdg main" >> /etc/apt/sources.list.d/pgdg.list'
wget -q https://www.postgresql.org/media/keys/ACCC4CF8.asc -O - | sudo apt-key add -
sudo apt-get update
sudo apt-get install postgresql-9.6
If postgresql installed successfully then it will return this after writing this command
psql --version
psql (PostgreSQL) 9.6.3

PostgreSQL is an open source object-relational database system. It is one of leading database server used for production servers. PostgreSQL allows us to execute stored procedures in various programming languages, like PHP, C/C++, Python, Java, Perl, Ruby and its own PL/pgSQL, which is similar to Oracle’s PL/SQL.
Postgres database is used the persistent store of data
Install Postgres
yum install postgres
(Note : remember the password for the postgres user – you need it later)
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install postgresql-9.6
Setting up Postgres
Launch pgAdmin.
Connect to the local server. Use localhost for the server name, postgres for the username and the password you used when you installed Postgres.
You need to be root to perform this command.Note: If you did not set password during installation (sudo apt-get install postgresql), then you can set it as follows:

sudo -u postgres psql postgres
On the postgres client prompt, use the following command to set the password.
alter user postgres with password 'postgres';
Connect to PostgreSQL
After installing PostgreSQL database server, by default,, it creates a user ‘postgres’ with role ‘postgres’. It also creates a system account with same name ‘postgres’. So to connect to postgres server, log in to your system as user postgres and connect database.
$ sudo su - postgres
$ psql
Now you are logged in to PostgreSQL database server. To check login info use following command from database command prompt.
postgres-# \conninfo
To disconnect from PostgreSQL database command prompt just type below command and press enter. It will return you back to Ubuntu command prompt.
postgres-# \q

PostgreSQL: duplication by one command [duplicate]

I'm looking to copy a production PostgreSQL database to a development server. What's the quickest, easiest way to go about doing this?

You don't need to create an intermediate file. You can do
pg_dump -C -h localhost -U localuser dbname | psql -h remotehost -U remoteuser dbname
or
pg_dump -C -h remotehost -U remoteuser dbname | psql -h localhost -U localuser dbname
using psql or pg_dump to connect to a remote host.
With a big database or a slow connection, dumping a file and transfering the file compressed may be faster.
As Kornel said there is no need to dump to a intermediate file, if you want to work compressed you can use a compressed tunnel
pg_dump -C dbname | bzip2 | ssh remoteuser#remotehost "bunzip2 | psql dbname"
or
pg_dump -C dbname | ssh -C remoteuser#remotehost "psql dbname"
but this solution also requires to get a session in both ends.
Note: pg_dump is for backing up and psql is for restoring. So, the first command in this answer is to copy from local to remote and the second one is from remote to local. More -> https://www.postgresql.org/docs/9.6/app-pgdump.html

pg_dump the_db_name > the_backup.sql
Then copy the backup to your development server, restore with:
psql the_new_dev_db < the_backup.sql

Use pg_dump, and later psql or pg_restore - depending whether you choose -Fp or -Fc options to pg_dump.
Example of usage:
ssh production
pg_dump -C -Fp -f dump.sql -U postgres some_database_name
scp dump.sql development:
rm dump.sql
ssh development
psql -U postgres -f dump.sql

If you are looking to migrate between versions (eg you updated postgres and have 9.1 running on localhost:5432 and 9.3 running on localhost:5434) you can run:
pg_dumpall -p 5432 -U myuser91 | psql -U myuser94 -d postgres -p 5434
Check out the migration docs.

pg_basebackup seems to be the better way of doing this now, especially for large databases.
You can copy a database from a server with the same or older major version. Or more precisely:
pg_basebackup works with servers of the same or an older major version, down to 9.1. However, WAL streaming mode (-X stream) only works with server version 9.3 and later, and tar format mode (--format=tar) of the current version only works with server version 9.5 or later.
For that you need on the source server:
listen_addresses = '*' to be able to connect from the target server. Make sure port 5432 is open for that matter.
At least 1 available replication connection: max_wal_senders = 1 (-X fetch), 2 for -X stream (the default in case of PostgreSQL 12), or more.
wal_level = replica or higher to be able to set max_wal_senders > 0.
host replication postgres DST_IP/32 trust in pg_hba.conf. This grants access to the pg cluster to anyone from the DST_IP machine. You might want to resort to a more secure option.
Changes 1, 2, 3 require server restart, change 4 requires reload.
On the target server:
# systemctl stop postgresql#VERSION-NAME
postgres$ pg_basebackup -h SRC_IP -U postgres -D VERSION/NAME --progress
# systemctl start postgresql#VERSION-NAME

Accepted answer is correct, but if you want to avoid entering the password interactively, you can use this:
PGPASSWORD={{export_db_password}} pg_dump --create -h {{export_db_host}} -U {{export_db_user}} {{export_db_name}} | PGPASSWORD={{import_db_password}} psql -h {{import_db_host}} -U {{import_db_user}} {{import_db_name}}

Run this command with database name, you want to backup, to take dump of DB.
pg_dump -U {user-name} {source_db} -f {dumpfilename.sql}
eg. pg_dump -U postgres mydbname -f mydbnamedump.sql
Now scp this dump file to remote machine where you want to copy DB.
eg. scp mydbnamedump.sql user01#remotemachineip:~/some/folder/
On remote machine run following command in ~/some/folder to restore the DB.
psql -U {user-name} -d {desintation_db}-f {dumpfilename.sql}
eg. psql -U postgres -d mynewdb -f mydbnamedump.sql

Dump your database : pg_dump database_name_name > backup.sql
Import your database back: psql db_name < backup.sql

I struggled quite a lot and eventually the method that allowed me to make it work with Rails 4 was:
on your old server
sudo su - postgres
pg_dump -c --inserts old_db_name > dump.sql
I had to use the postgres linux user to create the dump. also i had to use -c to force the creation of the database on the new server. --inserts tells it to use the INSERT() syntax which otherwise would not work for me :(
then, on the new server, simpy:
sudo su - postgres
psql new_database_name < dump.sql
to transfer the dump.sql file between server I simply used the "cat" to print the content and than "nano" to recreate it copypasting the content.
Also, the ROLE i was using on the two database was different so i had to find-replace all the owner name in the dump.

Let me share a Linux shell script to copy your table data from one server to another PostgreSQL server.
Reference taken from this blog:
Linux Bash Shell Script for data migration between PostgreSQL Servers:
#!/bin/bash
psql \
-X \
-U user_name \
-h host_name1 \
-d database_name \
-c "\\copy tbl_Students to stdout" \
| \
psql \
-X \
-U user_name \
-h host_name2 \
-d database_name \
-c "\\copy tbl_Students from stdin"
I am just migrating the data; please create a blank table at your destination/second database server.
This is a utility script. Further, you can modify the script for generic use something like by adding parameters for host_name, database_name, table_name and others

Here is an example using pg_basebackup
I chose to go this route because it backs up the entire database cluster (users, databases, etc.).
I'm posting this as a solution on here because it details every step I had to take, feel free to add recommendations or improvements after reading other answers on here and doing some more research.
For Postgres 12 and Ubuntu 18.04 I had to do these actions:
On the server that is currently running the database:
Update pg_hba.conf, for me located at /etc/postgresql/12/main/pg_hba.conf
Add the following line (substitute 192.168.0.100 with the IP address of the server you want to copy the database to).
host replication postgres 192.168.0.100/32 trust
Update postgresql.conf, for me located at /etc/postgresql/12/main/postgresql.conf. Add the following line:
listen_addresses = '*'
Restart postgres:
sudo service postgresql restart
On the host you want to copy the database cluster to:
sudo service postgresql stop
sudo su root
rm -rf /var/lib/postgresql/12/main/*
exit
sudo -u postgres pg_basebackup -h 192.168.0.101 -U postgres -D /var/lib/postgresql/12/main/
sudo service postgresql start
Big picture - stop the service, delete everything in the data directory (mine is in /var/lib/postgreql/12). The permissions on this directory are drwx------ with user and group postgres. I could only do this as root, not even with sudo -u postgres. I'm unsure why. Ensure you are doing this on the new server you want to copy the database to! You are deleting the entire database cluster.
Make sure to change the IP address from 192.168.0.101 to the IP address you are copying the database from. Copy the data from the original server with pg_basebackup. Start the service.
Update pg_hba.conf and postgresql.conf to match the original server configuration - before you made any changes adding the replication line and the listen_addresses line (in my care I had to add the ability to log-in locally via md5 to pg_hba.conf).
Note there are considerations for max_wal_senders and wal_level that can be found in the documentation. I did not have to do anything with this.

If you are more comfortable with a GUI, you can use the pgAdmin software.
Connect to your source and destination servers
Right-click on the source db > backup
Right-click on the destination server > create > database. Use the same properties as the source db (you can see the properties of the source db by right-click > properties)
Right-click on the created db > restore.

Copying PostgreSQL database to another server

I'm looking to copy a production PostgreSQL database to a development server. What's the quickest, easiest way to go about doing this?

You don't need to create an intermediate file. You can do
pg_dump -C -h localhost -U localuser dbname | psql -h remotehost -U remoteuser dbname
or
pg_dump -C -h remotehost -U remoteuser dbname | psql -h localhost -U localuser dbname
using psql or pg_dump to connect to a remote host.
With a big database or a slow connection, dumping a file and transfering the file compressed may be faster.
As Kornel said there is no need to dump to a intermediate file, if you want to work compressed you can use a compressed tunnel
pg_dump -C dbname | bzip2 | ssh remoteuser#remotehost "bunzip2 | psql dbname"
or
pg_dump -C dbname | ssh -C remoteuser#remotehost "psql dbname"
but this solution also requires to get a session in both ends.
Note: pg_dump is for backing up and psql is for restoring. So, the first command in this answer is to copy from local to remote and the second one is from remote to local. More -> https://www.postgresql.org/docs/9.6/app-pgdump.html

pg_dump the_db_name > the_backup.sql
Then copy the backup to your development server, restore with:
psql the_new_dev_db < the_backup.sql

Use pg_dump, and later psql or pg_restore - depending whether you choose -Fp or -Fc options to pg_dump.
Example of usage:
ssh production
pg_dump -C -Fp -f dump.sql -U postgres some_database_name
scp dump.sql development:
rm dump.sql
ssh development
psql -U postgres -f dump.sql

If you are looking to migrate between versions (eg you updated postgres and have 9.1 running on localhost:5432 and 9.3 running on localhost:5434) you can run:
pg_dumpall -p 5432 -U myuser91 | psql -U myuser94 -d postgres -p 5434
Check out the migration docs.

pg_basebackup seems to be the better way of doing this now, especially for large databases.
You can copy a database from a server with the same or older major version. Or more precisely:
pg_basebackup works with servers of the same or an older major version, down to 9.1. However, WAL streaming mode (-X stream) only works with server version 9.3 and later, and tar format mode (--format=tar) of the current version only works with server version 9.5 or later.
For that you need on the source server:
listen_addresses = '*' to be able to connect from the target server. Make sure port 5432 is open for that matter.
At least 1 available replication connection: max_wal_senders = 1 (-X fetch), 2 for -X stream (the default in case of PostgreSQL 12), or more.
wal_level = replica or higher to be able to set max_wal_senders > 0.
host replication postgres DST_IP/32 trust in pg_hba.conf. This grants access to the pg cluster to anyone from the DST_IP machine. You might want to resort to a more secure option.
Changes 1, 2, 3 require server restart, change 4 requires reload.
On the target server:
# systemctl stop postgresql#VERSION-NAME
postgres$ pg_basebackup -h SRC_IP -U postgres -D VERSION/NAME --progress
# systemctl start postgresql#VERSION-NAME

Accepted answer is correct, but if you want to avoid entering the password interactively, you can use this:
PGPASSWORD={{export_db_password}} pg_dump --create -h {{export_db_host}} -U {{export_db_user}} {{export_db_name}} | PGPASSWORD={{import_db_password}} psql -h {{import_db_host}} -U {{import_db_user}} {{import_db_name}}

Run this command with database name, you want to backup, to take dump of DB.
pg_dump -U {user-name} {source_db} -f {dumpfilename.sql}
eg. pg_dump -U postgres mydbname -f mydbnamedump.sql
Now scp this dump file to remote machine where you want to copy DB.
eg. scp mydbnamedump.sql user01#remotemachineip:~/some/folder/
On remote machine run following command in ~/some/folder to restore the DB.
psql -U {user-name} -d {desintation_db}-f {dumpfilename.sql}
eg. psql -U postgres -d mynewdb -f mydbnamedump.sql

Dump your database : pg_dump database_name_name > backup.sql
Import your database back: psql db_name < backup.sql

I struggled quite a lot and eventually the method that allowed me to make it work with Rails 4 was:
on your old server
sudo su - postgres
pg_dump -c --inserts old_db_name > dump.sql
I had to use the postgres linux user to create the dump. also i had to use -c to force the creation of the database on the new server. --inserts tells it to use the INSERT() syntax which otherwise would not work for me :(
then, on the new server, simpy:
sudo su - postgres
psql new_database_name < dump.sql
to transfer the dump.sql file between server I simply used the "cat" to print the content and than "nano" to recreate it copypasting the content.
Also, the ROLE i was using on the two database was different so i had to find-replace all the owner name in the dump.

Let me share a Linux shell script to copy your table data from one server to another PostgreSQL server.
Reference taken from this blog:
Linux Bash Shell Script for data migration between PostgreSQL Servers:
#!/bin/bash
psql \
-X \
-U user_name \
-h host_name1 \
-d database_name \
-c "\\copy tbl_Students to stdout" \
| \
psql \
-X \
-U user_name \
-h host_name2 \
-d database_name \
-c "\\copy tbl_Students from stdin"
I am just migrating the data; please create a blank table at your destination/second database server.
This is a utility script. Further, you can modify the script for generic use something like by adding parameters for host_name, database_name, table_name and others

If you are more comfortable with a GUI, you can use the pgAdmin software.
Connect to your source and destination servers
Right-click on the source db > backup
Right-click on the destination server > create > database. Use the same properties as the source db (you can see the properties of the source db by right-click > properties)
Right-click on the created db > restore.

Develop Reference

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