9 ways to backup and restore in Postgresql
Following are some of the commands I use to backup and restore my postgres databases and tables.
- pg_dump is a nifty utility designed to output a series of SQL statements that describes the schema and data of your database. You can control what goes into your backup by using additional flags.
Backup: pg_dump -h localhost -p 5432 -U postgres -d mydb > backup.sql
Restore: psql -h localhost -p 5432 -U postgres -d mydb < backup.sql-h is for host.
-p is for port.
-U is for username.
-d is for database. - Single transaction restore:
you can use –single-transaction in your restore command. It wraps out entire restore operation in one transaction, if something goes wrong it rollbacks all the changes.
psql –single-transaction -h localhost -p 5432 -U postgres -d mydb < backup.sql - Compressed Backup:
If your backup is too big, you can use any compression utility to compress it. I prefer gzip.
Backup: pg_dump -h localhost -p 5432 -U postgres -d mydb | gzip > backup.gz
Restore: gunzip -c backup.gz | psql -h localhost -p 5432 -U postgres -d mydb - Split Backup file:
If you are going to email your backup files or transfer them via any medium on internet I will suggest splitting the files into short files. You can use split utility for splitting the files with a size limit. In the example I am usinf 2mb size limit.
Backup: pg_dump -h localhost -p 5432 -U postgres -d mydb | split -b 2m – backup.sql
Restore: cat backup.sql* | psql -h localhost -p 5432 -U postgres -d mydb - Split compressed Backup file:
This is just a combination of point 3 and 4. We first compress the file then split it instead of splitting the plain file.
Backup: pg_dump -h localhost -p 5432 -U postgres -d mydb | gzip | split -b 1m – backup.gz
Restore: cat backup.gz* | gunzip | psql -h localhost -p 5432 -U postgres -d mydb - Parallel Backup:
You can allow pg_dump to dump the backup data in parallel by including the -j flag. It tells pg_dump the number of tables it can dump in parallel. Parallel backup only works when you use more than one files for writing backup data hence directory. -F d sets the format to directory and -f provides the directory name.
Backup: pg_dump -F d -f backup -j 20 -h localhost -p 5432 -U postgres -d mydb
Restore: pg_restore -F d -j 20 -h localhost -p 5432 -U postgres -d mydb backup - Backup of a specific table:
You can take backup of a specify table by adding -t flag.
Backup: pg_dump -h localhost -p 5432 -U postgres -d mydb -t my_table > backup.sql
Restore: psql -h localhost -p 5432 -U postgres -d mydb < backup.sql - Take Backup of all databases:
pg_dumpall is used to take backup of all of your postgresql database. I think it is just a wrapper around pg_dump. It will ask password for every database.
Backup: pg_dumpall -h localhost -p 5432 -U postgres > backup.sql
Restore: psql -h localhost -p 5432 -U postgres < backup.sql - Custom format backup (-F c):
Keith mentioned in the comment that -F c provides better options at the time of restoring the backup. You can take the backup of whole database and restore only selected tables by using -t flag. It also compresses the backup data for you.All these feature are also provided by the directory format (-F d) too. The main difference between directory and custom format is that custom format generates a single file and directory format generates a directory full of files. A Single file(single stream) gives us many advantages like outputting the backup data over SSH or transferring it to some other service is easy compared to a directory(multiple stream)One more difference is that you can not use parallel backup option (-j) with custom format backup. It is obvious since it uses only one stream.So how do you take backup using custom format and restore it.Backup: pg_dump -F c -h localhost -p 5432 -U postgres -d mydb > backup.dat
Restore: pg_restore -F c -h localhost -p 5432 -U postgres -t my_table -d mydb backup.dat
some other useful flags in pg_dump.
-v, –verbose verbose mode
-V, –version output version information, then exit
-?, –help show this help, then exit
-a, –data-only dump only the data, not the schema
-b, –blobs include large objects in dump
-c, –clean clean (drop) database objects before recreating
-C, –create include commands to create database in dump
-E, –encoding=ENCODING dump the data in encoding ENCODING
-n, –schema=SCHEMA dump the named schema(s) only
-N, –exclude-schema=SCHEMA do NOT dump the named schema(s)
-o, –oids include OIDs in dump
-O, –no-owner skip restoration of object ownership in plain-text format
-s, –schema-only dump only the schema, no data
-S, –superuser=NAME superuser user name to use in plain-text format
-t, –table=TABLE dump the named table(s) only
-T, –exclude-table=TABLE do NOT dump the named table(s)
-x, –no-privileges do not dump privileges (grant/revoke)
-V, –version output version information, then exit
-?, –help show this help, then exit
-a, –data-only dump only the data, not the schema
-b, –blobs include large objects in dump
-c, –clean clean (drop) database objects before recreating
-C, –create include commands to create database in dump
-E, –encoding=ENCODING dump the data in encoding ENCODING
-n, –schema=SCHEMA dump the named schema(s) only
-N, –exclude-schema=SCHEMA do NOT dump the named schema(s)
-o, –oids include OIDs in dump
-O, –no-owner skip restoration of object ownership in plain-text format
-s, –schema-only dump only the schema, no data
-S, –superuser=NAME superuser user name to use in plain-text format
-t, –table=TABLE dump the named table(s) only
-T, –exclude-table=TABLE do NOT dump the named table(s)
-x, –no-privileges do not dump privileges (grant/revoke)
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