Howto Backup PostgreSQL Databases Server With pg_dump command

Posted on in Categories Backup, Data recovery, Howto, Linux, Postgresql, UNIX last updated April 27, 2008

Generally, I like to work with MySQL but some time my work force me to work with PostgreSQL database server.

Recently I had received a request to backup PostgreSQL databases as one of our client want to format and reinstall RHEL server.

PostgreSQL is a one of the robust, open source database server. Like MySQL database server, it provides utilities for creating a backup.

Step # 1: Login as a pgsql user

Type the following command:
$ su - pgsql
Get list of database(s) to backup:
$ psql -l

Step # 2: Make a backup using pg_dump

Backup database using pg_dump command. pg_dump is a utility for backing up a PostgreSQL database. It dumps only one database at a time. General syntax:
pg_dump databasename > outputfile

Task: dump a payroll database

Type the following command
$ pg_dump payroll > payroll.dump.outTo restore a payroll database:
$ psql -d payroll -f payroll.dump.outOR$ createdb payroll
$ psql payroll
However, in real life you need to compress database:$ pg_dump payroll | gzip -c > payroll.dump.out.gzTo restore database use the following command:$ gunzip payroll.dump.out.gz
$ psql -d payroll -f payroll.dump.out
Here is a shell script for same task:

#!/bin/bash
DIR=/backup/psql
[ ! $DIR ] && mkdir -p $DIR || :
LIST=$(psql -l | awk '{ print $1}' | grep -vE '^-|^List|^Name|template[0|1]')
for d in $LIST
do
  pg_dump $d | gzip -c >  $DIR/$d.out.gz
done

Another option is use to pg_dumpall command. As a name suggest it dumps (backs up) each database, and preserves cluster-wide data such as users and groups. You can use it as follows:$ pg_dumpall > all.dbs.outOR$ pg_dumpall | gzip -c > all.dbs.out.gzTo restore backup use the following command:
$ psql -f all.dbs.out postgresReferences:

29 comment

  1. sir,
    i am not able to take the backup of postgresql database.in pg_dump commnad it provide me “access denied ”
    thanks

  2. Man, please remember that if you use the gzip option with pg_dumpall you HAVE TO use the gunzip to restore the backup.

    gunzip all.dbs.out.gz

    and then

    psql -f all.dbs.out postgres

  3. The script has a little bug. On,
    LIST=$(psql -l | awk ‘{ print $1}’ | grep -vE ‘^-|^List|^Name|template[0|1]’)

    if you have a list with several databases, the last row is number. For example in my case:
    (19 rows)
    and after the script
    (19

    so I propose you generate the LIST with this:
    LIST=$(psql -l | awk ‘{ print $1}’ | grep -vE ‘^-|^List|^Name|template[0|1]|^\(‘)

    Otherwise, it’s a very nice article.

    Thanks.

  4. Thanks Vivek for the great script.

    Just a few notes:

    In the 3rd line
    [ ! $DIR ] && mkdir -p $DIR || :
    there should be no space character after the exclamation mark!
    [ !$DIR ] && mkdir -p $DIR || :
    like this it works for me.

    @Leopold, thanks for your comment, I had the same problem and your expression for LIST was the solution :)

  5. i have taken backup of DB from other machine. so i want the run those DB on my box.

    what are the steps i need to follow to achive it.

    please help me

  6. Needed help,new person in software using POSTGRE SQL please guide me with commands that will help to take backup easily and similarly restore when needed.

  7. Nice tip, thanks. I have a few notes to share.

    You can also avoid the number of rows returned with the “-t” option to psql:

    psql -lt

    Also, to run the script as root from cron, I used su to run the backup as the postgres user. My complete script:

    #!/bin/sh
    DIR=/backup/pgsql
    
    LIST=$(su - postgres -c "psql -lt" |awk '{ print $1}' |grep -vE '^-|^List|^Name|template[0|1]')
    
    for d in $LIST
    do
      su - postgres -c "/usr/bin/pg_dump $d | gzip -c > $DIR/$d.sql.gz"
    done
    
  8. Hi
    I want take backup from Postgresql in Tehran (city in Iran) and store it in Sqlserver 2005 in Mashad (city in Iran). Is it possible? How can I do it?
    Regards,
    Hamidreza

  9. Hi. I had a slightly different experience. My cron job runs under root, but wanted to run the psql code under postgres user. My script therefore had to be changed to (Note the PGPASSWORD being set AND removed at the end):

    #!/bin/bash
    export PGPASSWORD=XXXXX
    DIR=/home/ben/backups/psql
    [ !$DIR ] && mkdir -p $DIR || :
    LIST=$(su postgres -c “psql -lt” |awk ‘{ print $1}’ |grep -vE ‘^-|^List|^Name|template[0|1]’)
    for d in $LIST
    do
    pg_dump -U postgres $d | gzip -c > $DIR/$d.out.gz
    done
    export PGPASSWORD=

  10. Nice,
    For my case, I add split to have many files and can store it in dumy filesystem
    pg_dumpall -Upostgres | gzip -c | split --bytes=1000m

    Regards

  11. I got errors like this:
    -su: /tmp/pgsql/erpengdemo.sql.gz: Permission denied
    and tish:
    pg_dump: [archiver (db)] connection to database “:” failed: FATAL: database “:” does not exist

    And work around was:

    #!/bin/sh
    DIR=/backup/pgsql
    [ !$DIR ] && mkdir -p $DIR || :

    chown postgres:postgres $DIR

    LIST=$(su – postgres -c “psql -lt” |awk ‘{ print $1}’ |grep -vE ‘^-|:|^List|^Name|template[0|1]’)

    for d in $LIST
    do
    su – postgres -c “/usr/bin/pg_dump $d | gzip -c > $DIR/$d.sql.gz”
    done

  12. I got errors like this:
    -su: /tmp/pgsql/erpengdemo.sql.gz: Permission denied
    and tish:
    pg_dump: [archiver (db)] connection to database “:” failed: FATAL: database “:” does not exist

    And work around was:

    #!/bin/sh
    DIR=/backup/pgsql
    [ !$DIR ] && mkdir -p $DIR || :

    chown postgres:postgres $DIR

    LIST=$(su - postgres -c "psql -lt" |awk '{ print $1}' |grep -vE '^-|:|^List|^Name|template[0|1]')

    for d in $LIST
    do
    su - postgres -c "/usr/bin/pg_dump $d | gzip -c > $DIR/$d.sql.gz"
    done

  13. My version of script. The differencies:
    1. I am asking psql to output databases without header (-t)
    2. Simplified awk call to get rid of colons

    #!/bin/bash
    DIR=/backup/psql
    LIST=$(psql -l -t -U root | awk 'NF >=5 { print $1}')
    for d in $LIST; do
      pg_dump $d | gzip -c >  $DIR/$d.out.gz
    done
  14. Even better version :)

    #!/bin/bash
    #
    # Dayly PostgreSQL maintainance: vacuuming and backuping.
    #
    ##
    
    set -e
    
    for DB in $(psql -l -t -U root | awk 'NF >=5 { print $1}' | grep -v template0); do
      echo "[`date`] Maintaing $DB"
      echo 'VACUUM' | psql -U root -d $DB
      DUMP="$DB.`date '+%Y%m%d'`.sql.gz"
      PREV="$DB.`date -d'1 day ago' '+%Y%m%d'`.sql.gz"
      pg_dump -U root $DB | gzip -c > $DUMP
      md5sum -b $DUMP > $DUMP.md5
      if [ -f $PREV.md5 ] && diff $PREV.md5 $DUMP.md5; then
        rm $DUMP $DUMP.md5
      fi
    done
    1. I’ve made some script good for cron… It also has impemented restore commands for created backups :) and expiration limit (rotating)

      
      #!/bin/bash
      #
      # Little script for PGSQLdump all databases (seperate files)
      #
      # v20100519 -- initial version by Koco
      #
      ############################################################
      MYEXECNAME=backup_postgres_v8.4_dbs_script.bash
      
      USER=postgres
      PGSQLCMD="/postgres1/v8.4.0/bin/psql --port 5433"
      PGSQLCMDlist="$PGSQLCMD -l -t"
      PGSQLdumpCMD="/postgres1/v8.4.0/bin/pg_dump --port 5433 -C"
      
      APPEND=`date "+%Y%m%d-%H%M"`
      BASEDIR=/postgres1/BACKUPS
      BKPDIR=$BASEDIR/bkpV8.4.$APPEND
      RSTFILE=$BASEDIR/bkpV8.4.$APPEND/1_restore_commands.README
      
      #How many days do you wanna keep backups
      TRESHOLD=30
      
      if [ -f /postgres1/.postvolume ]
      then
       DATABASES=`su - $USER -c "$PGSQLCMDlist" |grep \| |awk '{ print $1}'| grep -vE '^-|^List|^Name|template[0|1]'`
       mkdir $BKPDIR
       for db in $DATABASES
       do
         su - $USER -c "$PGSQLdumpCMD $db" | bzip2 -c > $BKPDIR/$db.dump.bz2
         echo "#---restore $db" >> $RSTFILE
         echo "bzcat $BKPDIR/$db.dump.bz2 > $BASEDIR/RST.dump.sql" >> $RSTFILE
         echo "su - $USER -c \"$PGSQLCMD -d $db -f $BASEDIR/RST.dump.sql\" " >> $RSTFILE
         echo "rm $BASEDIR/RST.dump.sql" >> $RSTFILE
         echo "#" >> $RSTFILE
       done
      fi
      
      
      # And find those old ones... and delete them (use nwrecover if you need them back)
      FILES=`find $BASEDIR -type d -name 'bkpV8.4.*' -mtime +$TRESHOLD`
      for f in $FILES
      do
        echo "$APPEND: Treshold reached. Removed $f backup." >> $BASEDIR/$MYEXECNAME.log
        rm -rf $f
      done
      
      
  15. Hi,
    I’m having problems with script and commands. could you help me with it?

    #!/bin/bash
    DIR=”/var/lib/pgsql”
    BASE=”coupons”
    DATE=”date +%m%d”

    pg_dump $BASE | gzip > $DATE.coupons.gz
    exit

  16. Hi everyone,
    I am new to freebsd, and I used postgresql for my database management.
    There was this scenario that i accidentally delete this particular database
    and the backup setting for our server is not one by one, meaning all databases.

    My question is how can I restore that particular database using the backup file which is a compressed file which is composed of several database?
    Is there a way to extract a particular database on that file?

  17. Another version to get the list of databases:
    psql -lqt | grep -vE ‘^ +(template[0-9]+|postgres)? *\|’ | cut -d’|’ -f1| sed -e ‘s/ //g’ -e ‘/^$/d’

    As my `psql -lqt` output is:
    abcdefghij | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
    postgres | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
    template0 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
    | | | | | postgres=CTc/postgres
    template1 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
    | | | | | postgres=CTc/postgres
    abc | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 |

  18. HI,

    > Does RHEL supports auto backup and restoration for PostgreSQL? If yes how to configure.
    > Does Ubuntu supports auto backup and restoration for PostgreSQL? If yes how to configure.

    Thanks
    Tilak

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