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Backup and Restore PostgreSQL Database

PostgreSQL has been shipped with a lot of tools for ease of managing the database. Some actions that we typically perform in managing databases are backing up a database and restoring it to another database server. In PostgreSQL, we can utilize pg_dump to back up the data from a database and psql or pg_restore to restore the data into a new database.


Generating A Backup File

There are several available formats for the exported data: plain, directory, compressed, and custom. The plain format is using plain SQL syntax to export the data. To make the tables are exported separately, we can utilize directory format. The custom format is utilizing a built-in compression mechanism and results in an optimized binary formatted file. It is suitable for a large database. If we use a custom format, we can only restore it using pg_restore, but we have the ability to selectively choose desired tables to be restored.

The following command is used to generate a plain formatted file with the INSERT syntax as the SQL command for inserting records. The file parameter is used to specify the destination file to store the result.

pg_dump \
  --host=localhost \
  --port=5432 \
  --username=postgres \
  --password \
  --dbname=mydatabase
  --file=outputFilePlain \
  --format=p \
  --inserts \
  --no-owner \
  --no-privileges

The following command is used to generate a custom formatted file.

pg_dump \
  --host=localhost \
  --port=5432 \
  --username=postgres \
  --password \
  --dbname=mydatabase
  --file=outputFileCustom \
  --format=c \
  --inserts \
  --no-owner \
  --no-privileges

Restoring Database from A Backup File

As I have mentioned above, we can utilize psql or pg_restore to restore the database from a backup file. But, only the pg_restore command can be used to restore the custom formatted file.

The following command is used to restore a database from a plain formatted file. We must create the destination database first before running this command. The file parameter is used to specify the source file.

psql \
  --host=localhost \
  --port=5432 \
  --username=postgres \
  --password \
  --dbname=mynewdatabase \
  --file=inputFilePlain

The following command is used to restore the database from a custom formatted file using pg_restore. We need to notice that the last part is the name of the input file without the name of a command parameter.

pg_restore \
  --host=localhost \
  --port=5432 \
  --username=postgres \
  --password \
  --dbname=mynewdatabase \
  inputFileCustom


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