Earlier today I was troubleshooting some resource issues on a PostgreSQL server and needed to test some various SELECT statements to see if any of them were causing problems. I also wanted to verify the amount of resources a SELECT statement made using PGAdmin versus the amount of resources the same SELECT statement used running it directly on the Postgres server itself. Below is information on how to run a SELECT statement from a Linux shell. In this example the server is running CentOS Linux and PostgreSQL 8.4.4.
This afternoon I was using PGAdmin and needed to export some data from a query I had run but realized I wasn’t even sure if PGAdmin had this capability. Typically I would export data using the PSQL command line but since I was already working in PGAdmin I wanted to try and figure out if the capability existed and if so how to do it. After some playing around I was able to figure out how to export PGAdmin data to a CSV (Comma Separated Value) format that would be Microsoft Excel friendly. Follow the directions below to export PGAdmin data to a .CSV file to open in MS Excel.
When connecting to a PostgreSQL database using pgAdmin you may receive an error letting you know that the server instrumentation is not installed. This is a warning to let you know that you can install the adminpack contribution which will provide more functionality to pgAdmin including the ability to modify the pg_hba.conf and postgresql.conf configuration files. Below is information on the pop up warning you may receive when logging into a Postgres database using pgAdmin III as well as how to install the adminpack to not receive the error any longer.
Earlier this evening I ran into a unique issue where a PostgreSQL table had been created with no primary key this allowing duplicate rows to exist in the database table. You are unable to delete such rows in a SQL table because there is no primary key. After not being able to delete the rows via the PSQL CLI I opened pgAdmin III to see if I could delete the rows using the GUI interface provided by pgAdmin III however the delete was grey in the menu as shown in the below image.
Backing up and restoring a postgreSQL database is easy from the CLI. Some people prefer using pgAdmin III however through the GUI and over a network will use a lot more resources so it is recommended to backup and restore via your Linux CLI. Follow the simple steps below to backup and restore one Postgres database from a Linux server to another Linux server.
- Backup One PostgreSQL Database: Login to your server and issue the below command from the CLI. In the below syntax change username to the correct username (such as postgres), the database_name to the proper database, and the filename to something meaningful. The filename should end in .sql so you know it is a postgreSQL backup file which will eventually end in .gz once you compress it using gzip.