PostgreSQL Dump Import: How to Restore PostgreSQL Databases? | 3 Easy Methods

on Database Management Systems, PostgreSQL • February 14th, 2022 • Write for Hevo

PostgreSQL Dump Import FI

The concept behind the PostgreSQL Dump Import approach is to create a text file containing SQL commands that, when sent back to the server, will reconstruct the database in the same state as it was when the dump was performed. For this, PostgreSQL provides the pg_dump utility function. The PostgreSQL client application pg_dump is a standard PostgreSQL client (albeit a particularly clever one). This implies you can backup the database from any remote system that has access to the database. 

In this article, you will learn everything about ways to recover data with PostgreSQL Dump Import along with the process which you might want to carry out while using it to make the process run smoothly. You will also learn about a No-code data pipeline to carry out this process.

Table of Contents

What is PostgreSQL?

PostgreSQL Dump Import: PostgreSQL logo
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PostgreSQL, or Postgres, is a free, open-source Relational Database Management System (RDBMS) that focuses on extensibility and SQL compliance. It was first released on July 8, 1996, and was developed at the University of California, Berkeley. It was the Ignes database’s successor. Instead of storing data in the form of documents, PostgreSQL uses Structured objects. It uses the standard SQL syntax and style.

It’s written in C and has a monolithic architecture, which means all of the parts are connected and work in a logical order. It provides community assistance as well as further assistance to some of its paid customers. Because of its novel backup systems, it is frequently employed in the Healthcare, Finance, and Industrial industries.

Key Features of PostgreSQL

PostgreSQL has some distinguishing characteristics that make it a viable alternative to other standard RDBMSs. The following are some of these characteristics:

  • It is ACID (Atomicity, Consistency, Isolation, and Durability) compliant and runs on major operating systems.
  • Storage is reliable because of various fail-safes and redundancy.
  • Since it is open-source, anyone can utilize all of its features for free.
  • Since its processing capacity depends on the system it runs on, it supports limited scalability.
  • PostgreSQL can handle a wide range of data, documents, and customization kinds.
  • It features a Monolithic Architecture, which means that all of the components function together automatically.
  • It has a strong Access Control System with features such as row and column level security and multi-factor authentication with certificates.

To learn more about PostgreSQL, you can check the official website here.

What is a PostgreSQL Database Dump?

pg_dump is a backup tool for PostgreSQL databases. Even if the database is in use at the same time, it creates consistent backups. Other users are not prevented from accessing the database via pg_dump (readers or writers).

pg dump only dumps one database at a time. Use pg_dumpall to backup global objects that are shared by all databases in a cluster, such as roles and tablespaces.

Dump files can be saved as scripts or archive files. Script dumps are text files that include the SQL commands needed to restore the database to the state it was in when it was saved. Feed it to psql to restore from such a script. Script files can be used to rebuild the database on various machines and architectures, as well as on other SQL database solutions with some adjustments.

To rebuild the database, various archive file formats must be utilised using pg_restore. They allow pg_restore to be picky about what it restores, and even reorder items before they’re restored. The archive file formats were created with portability in mind.

When paired with pg_restore and one of the archive file formats, pg_dump provides a versatile archival and transfer method. pg_dump can backup a complete database, and then pg_restore can review the archive and/or decide which sections of the database should be restored. The “custom” format (-Fc) and the “directory” format are the most flexible output file formats (-Fd). They offer parallel restoration and are compressed by default, and they allow for the selection and reordering of all archived objects. The only format that allows for concurrent dumps is the “directory” type.

While executing pg_dump, look for any warnings in the output (printed on standard error).

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Why Should you Backup your PostgreSQL Database?

Let’s understand the purpose of carrying out PostgreSQL Dump Import. The purpose to have backups or prepare for backups is to avoid data loss and maintain continuity. There are a variety of reasons for data loss, but here is a handful that is most commonly seen:

  • Data Corruption: The most significant and critical factor is Data Corruption. Even if you have numerous clones, the rot will almost certainly spread (way faster than you believe) throughout them, rendering them useless for operating any kind of production.
  • Device Failure: It is a very common occurrence. This can result in the entire data center becoming inaccessible, causing all operating instances to become unavailable, and requiring the cluster to be rebuilt from a backup.
  • Human Error: This one swiftly spreads throughout all clones. Try dropping the table and then stopping it from duplicating. Despite taking several measures, a slip can always occur, putting you in a precarious situation.
  • Program Errors: There will always be a bug somewhere in the software that is being used. It could be a problem with the operating system or with network transfers, resulting in missing bits or bytes and unexpected outcomes.
  • Compliance Requirements and Retention Policies: Depending on your industry type, you may need to retain or store data for a certain period of time in order to stay compliant. You might be required to keep backup copies of your data in order to ensure that any changes can be tracked/ reverted over that period.

PostgreSQL Dump Import: Ways to Recover 

Method 1: PostgreSQL Dump Import Restore using PSQL Command

What is the PSQL Command? 

If your backup is a plain-text file with SQL Scripts, you can restore your database by using the following command in the PostgreSQL interactive terminal: 

psql -U db_user db_name < dump_name.sql

where db_user is the database user, db_name is the database name, and dump_name.sql is the name of your backup file.

Syntax: 

psql [option...] [dbname [username]]

When Should you use PSQL Command?

psql is a terminal-based PostgreSQL front-end. It allows you to enter Interactive Queries, send them to PostgreSQL, and view the results. Input can also come from a file or through command line arguments. psql also has a number of meta-commands and shell-like capabilities that make building scripts and automating a range of activities easier.

How to Restore PostgreSQL Data using PSQL Command?

PostgreSQL Dump Import process can be carried out using psql command. You can use the psql utility to recover the SQL script file created by pg_dump, pg_dumpall, or any other tool that creates compatible backup files. You can run the complete script in the dump file with the psql tool.

Use the following command to restore a full backup while ignoring any errors that may have occurred during the restoration process:

psql -U username -f backupfile.sql

If you wish to prevent a database from being restored if there are issues, use the —set ON_ERROR_STOP=on option:

psql -U username --set ON_ERROR_STOP=on -f backupfile

If you have made a backup of objects in a database, you can restore them with the following command:

psql -U username -d database_name -f objects.sql

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Method 2: PostgreSQL Dump Import Restore using Pg_Restore Command

What is the Pg_Restore Command? 

If you choose custom, directory, or archive format while creating a backup file, you’ll have to restore your database with pg_restore:

pg_restore -d db_name /path/to/your/file/dump_name.tar -c -U db_user

If you use pg restore, you can choose from a number of settings, such as:

  • To remove database objects before recreating them, use the –c option.
  • To construct a database before restoring it, use the -C option.
  • If an error occurs, leave with -e.
  • -F format specifies the archive’s format.
  • To get the entire list of available options, type pg_restore -?

By running man pg_dump, man psql, and man pg_restore, you may learn more about how to use the tools described.

Syntax: 

pg_restore [connection-option...] [option...] [filename]

When Should you use Pg_Restore Command?

pg_restore is a utility that allows you to restore a PostgreSQL database from a non-plain-text archive produced by pg_dump. It will execute the procedures required to restore the database at an earlier state. The archive files also allow pg_restore to be picky about what it restores and even reorder the items before restoring them. The archive files are designed to be cross-platform compatible.

pg_restore has two modes of operation. If a database name is given, pg_restore connects to it and restores the contents of the archive into the database. Otherwise, a script is written to a file or standard output providing the SQL statements required to recreate the database. This script’s output is the same as pg_dump‘s plain text output format. As a result, several of the output control options are similar to pg dump options.

Obviously, pg_restore won’t be able to restore data that isn’t in the archive file. For example, pg_restore will not be able to load the data using COPY statements if the archive was created using the “dump data as INSERT commands” option.

How to Restore PostgreSQL Data using Pg_Restore Command?

You can restore data with PostgreSQL Dump Import backed up by pg_dump or pg_dumpall tools using the pg_restore application instead of psqltool. You can restore databases using the pg restore software in a variety of ways, for example:

  • Using the -j option to define the number of threads for restoration, you can conduct parallel restores with pg_restore. Each thread restores a distinct table at the same time, greatly speeding up the operation. Currently, the pg_restore supports this option for the only Custom File Format.
  • You can also use the pg_restore command to restore select Database items from a backup file that contains the entire Database.
  • The pg_restore command can restore a database that was backed up in an older version to a later version.

To practice with the pg_restore tool, create a new database called newdvdrental.

CREATE DATABASE newdvdrental;

Using the following command, you may restore the dvdrental database in tar file format created by the pg_dump tool in the PostgreSQL backup database tutorial:

pg_restore --dbname=newdvdrental 
--verbose c:pgbackupdvdrental.tar

You can use the following command to restore a database that is identical to the one from which the backup was taken:

pg_restore --dbname=dvdrental --create --verbose 
c:pgbackupdvdrental.tar

Since PostgreSQL 9.2, the —section option can be used to restore simply the table structure. This gives you the option of using the new database as a template for future databases.

Create a new database called dvdrental_tpl first.

CREATE DATABASE dvdrental_tpl;

Second, use the following command to restore the table structure just from the dvdrental.tar backup file:

>pg_restore --dbname=dvdrental_tpl --section=pre-data  c:pgbackupdvdrental.tar

Method 3: Using Hevo Data, a No-code Data Pipeline for PostgreSQL Dump Import

PostgreSQL Dump Import
Source: Self

Hevo is a No-code Data Pipeline. It supports pre-built data integrations via 150+ data connectors(including 40+ free sources) such as PostgreSQL. Hevo offers a fully managed solution for your fully automated pipeline to directly load data to PostgreSQL from all your data sources. It will automate your data flow in minutes without writing any line of code. Its fault-tolerant architecture makes sure that your data is secure and consistent. Users can connect Hevo with their PostgreSQL Database.

Hevo supports connecting with PostgreSQL as a source database and as a Destination Database. Plus, with Hevo’s No-code approach, you can replicate data using the Log-based approach and leverage WAL Files to ensure Real-time replication, all without writing any code. It helps carry out processes like PostgreSQL Dump Import.

Hevo focuses on these simple steps below to get you started

Step 1: Add Destination

Choose one of the following options:

  • Click ADD DESTINATION once you’ve configured the Source during Pipeline building.
  • In the Asset Palette, click DESTINATIONS, and then + CREATE in the Destinations List View.

Step 2: Select the Destination Type

Select PostgreSQL from the Add Destination page. Alternatively, search for the Destination using the Search Destination Type search box.

Step 3: Configure PostgreSQL Connection Settings 

In the Configure your PostgreSQL Destination page, make the following changes:

PostgreSQL Dump Import: Destination Configuration
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Step 4: Test Connection 

To test connectivity to the Destination Postgres server, put in the details and then click TEST CONNECTION.

Step 5: Save Connection

When the test is complete, click SAVE DESTINATION to save the connection.

As can be seen, you are simply required to enter the corresponding credentials to implement this fully automated data pipeline without using any code. Hevo supports data ingestion for replication from PostgreSQL servers. Learn more about Hevo’s integration with PostgreSQL here.

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Conclusion

This article teaches you about ways to recover data with PostgreSQL Dump Import. It provides in-depth knowledge about the concepts behind every step to help you understand and implement them efficiently. In case you want to transfer data into your desired Database/destination, then Hevo Data is the right choice for you! 

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Hevo provides its users with a simpler platform for integrating data via 150+ data connectors (including 40+free sources such as Google Sheets) for Analysis. It is a No-code Data Pipeline that can help you combine data from multiple sources. You can use it to transfer data from multiple data sources into your Data Warehouses, Databases such as PostgreSQL, or a destination of your choice.

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