Wednesday, 25 March 2020

pg_restore with -C option fails to create database. FATAL: database "nexaprod" does not exist

When you use pg_restore you have various options available, for example : 

-c to drop database objects before recreating them,
-C to create a database before restoring into it,
-e exit if an error has encountered,
-F format to specify the format of the archive.

I tried to replicate this. I created an object in database nexaprod which is running on port 5432.


nexaprod =# CREATE TABLE tutorials (id int, tutorial_name text);
CREATE TABLE
nexaprod =# \d
           List of relations
 Schema |   Name    | Type  |  Owner
--------+-----------+-------+----------
 public | tutorials | table | postgres
(1 row)
                  



Now I wish to restore this database to another cluster of port 5433 as below:


-bash-4.1$ /usr/pgsql-9.6/bin/pg_restore -d nexaprod /var/lib/pgsql/newdb1.tar -C -p 5433
pg_restore: [archiver (db)] connection to database " nexaprod" failed: FATAL:  database " nexaprod" does not existt


What I've got in file wrote above 'create database' so this database does not exist when I’m running script.

That's what for there is always 'postgres' database. So, I tried something as this :


-bash-4.1$ /usr/pgsql-9.6/bin/pg_restore -C -d postgres -v -p 5433  /var/lib/pgsql/nexaprod.tar

pg_restore: connecting to database for restore
pg_restore: creating DATABASE "nexaprod"
pg_restore: connecting to new database "nexaprod"
pg_restore: connecting to database "nexaprod" as user "postgres"
pg_restore: creating SCHEMA "public"
pg_restore: creating COMMENT "SCHEMA public"
pg_restore: creating EXTENSION "plpgsql"
pg_restore: creating COMMENT "EXTENSION plpgsql"
pg_restore: creating TABLE "public.tutorials"
pg_restore: processing data for table "public.tutorials"
pg_restore: creating ACL "SCHEMA public"
pg_restore: creating ACL "public.TABLE tutorials"

-bash-4.1$ psql -p 5433



The above states that :

-         pg_restore will initially connect to the database specified with -d. It will NOT create that database.

-            The -d will restore in the given database if and only if -C is not used.

-        It creates a database with the name from the archive you are restoring and restores the data into that database, when used -C.


So, basically what above did is :
1. connect to postgres database
2. Create database -nexaprod
3. Disconnect from postgres and connect to -nexaprod
4. Upload data into database -nexaprod


Alternatively, we can use below command to restore the dump with different DB name.

$ cat /var/lib/pgsql/nexaprod.tar | psql nexa_dev -p 5433


postgres=#  create database nexa_dev ;
CREATE DATABASE
postgres=# \q
-bash-4.1$ cat /var/lib/pgsql/nexaprod.tar | psql nexa_dev -p 5433


postgres=# \l
                                  List of databases
   Name    |  Owner   | Encoding |  Collation  |    Ctype    |   Access privileges
-----------+----------+----------+-------------+-------------+-----------------------
 nexa_dev  | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |
 nexaprod  | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |


postgres=# \c nexa_dev
You are now connected to database "nexa_dev".

nexa_dev=# \d
           List of relations
 Schema |   Name    | Type  |  Owner
--------+-----------+-------+----------
 public | tutorials | table | postgres

(1 row)


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