Howto Backup and Restore PostgreSql database using pg dump and psql

1. Backup a single postgres database

This example will backup erp database that belongs to user geekstuff, to the file mydb.sql

$ pg_dump -U geekstuff erp -f mydb.sql

It prompts for password, after authentication mydb.sql got created with create table, alter table and copy commands for all the tables in the erp database. Following is a partial output of mydb.sql showing the dump information of employee_details table.

--
-- Name: employee_details; Type: TABLE; Schema: public; Owner: geekstuff; Tablespace:
--

CREATE TABLE employee_details (
employee_name character varying(100),
emp_id integer NOT NULL,
designation character varying(50),
comments text
);

ALTER TABLE public.employee_details OWNER TO geekstuff;

--
-- Data for Name: employee_details; Type: TABLE DATA; Schema: public; Owner: geekstuff
--
COPY employee_details (employee_name, emp_id, designation, comments) FROM stdin;
geekstuff 1001 trainer
ramesh 1002 author
sathiya 1003 reader
\.
--
-- Name: employee_details_pkey; Type: CONSTRAINT; Schema: public; Owner: geekstuff; Tablespace:
--
ALTER TABLE ONLY employee_details

ADD CONSTRAINT employee_details_pkey PRIMARY KEY (emp_id);

2. Backup all postgres databases

To backup all databases, list out all the available databases as shown below.

$ su postgres

$ psql -l

List of databases
Name | Owner | Encoding
-----------+-----------+----------
article | sathiya | UTF8
backup | postgres | UTF8
erp | geekstuff | UTF8
geeker | sathiya | UTF8

$ pg_dumpall > all.sql

$ grep "^[\]connect" all.sql
\connect article
\connect backup
\connect erp
\connect geeker

3. Backup a specific postgres table

$ pg_dump --table products -U geekstuff article -f onlytable.sql

To backup a specific table, use the –table TABLENAME option in the pg_dump command. If there are same table names in different schema then use the –schema SCHEMANAME option.

1. Restore a postgres database

$ psql -U erp -d erp_devel -f mydb.sql

This restores the dumped database to the erp_devel database.

psql:mydb.sql:13: ERROR:  must be owner of schema public
psql:mydb.sql:34: ERROR:  must be member of role "geekstuff"
psql:mydb.sql:59: WARNING:  no privileges could be revoked
psql:mydb.sql:60: WARNING:  no privileges could be revoked
psql:mydb.sql:61: WARNING:  no privileges were granted
psql:mydb.sql:62: WARNING:  no privileges were granted

2. Backup a local postgres database and restore to remote server using single command:

$ pg_dump dbname | psql -h hostname dbname

The above dumps the local database, and extracts it at the given hostname.

3. Restore all the postgres databases

$ su postgres
$ psql -f alldb.sql

4. Restore a single postgres table

The following psql command installs the product table in the geek stuff database.

$ psql -f producttable.sql geekstuff

This article was written by SathiyaMoorthy, developer of Enterprise Postgres Query Analyser, an efficient tool for parsing postgresql log to generate html report, which can be used for fine tuning the postgres settings, and sql queries. The Geek Stuff welcomes your tips and guest articles.

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