Database Technologies: Some trigger and programming feature in PostgreSQL

Database Technologies: Some trigger and programming feature in PostgreSQL

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Remote Log Reading in PostgreSQL 8.4 and 9.0.

I was going through the one of the important feature (SQL/MED) which is coming feature of PostgreSQL 9.1. This feature enables user to access any external file, using SQL, from PostgreSQL Terminal. Magnus hagander's has also blogged about this feature and he has shown "How to access the PostgreSQL logfile using SQL/Med" . After going through his blog, I thought to do same with PostgreSQL 8.4/9.0 using plperl program. Following are the steps, which can be use to access the postgreSQL csv log file: 1. Change the log_destination parameter in postgresql.conf file of PG Instance Directory, to create csvlog of postgreSQL log. As given below. log_destination = 'stderr,csvlog' 2. Reload the changes in PostgreSQL, using following command: postgres=# select pg_reload_conf(); pg_reload_conf ---------------- t (1 row) 3. Connect to PostgreSQL database using psql command and Create following data type CREATE type pg_log_type as ( log_time timestamp(3) with ti...
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UPSERT/MERGE using Writable CTE in PostgreSQL 9.1

There is always discussion of having UPSERT/MERGE in postgresql. Since, oracle and other RDBMS has this feature, therefore people ask about this feature in PostgeSQL. In previous version of PostgreSQL, we used to implement it using functions. Now in PostgreSQL 9.1, user can implement this feature using Writable CTE. PostgreSQL 9.1, now has Writable CTE using WTH. WITH provides a way to write auxiliary statements for use in a larger query. These statements, which are often referred to as Common Table Expressions or CTEs, can be thought of as defining temporary tables that exist just for one query. Each auxiliary statement in a WITH clause can be a SELECT, INSERT, UPDATE, or DELETE; and the WITH clause itself is attached to a primary statement that can also be a SELECT, INSERT, UPDATE, or DELETE. Lets see how we can use Writable CTE for UPSERT. Following are SQL Code which can be use in Oracle and PostgreSQL for creating sample data: For oracle: create table myTable (pid ...
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PostgreSQL Database Link to Oracle Database on Linux

I have seen question, like "How to make Database Link from PostgreSQL to Oracle?", always floats in PostgreSQL Community Forum. So, I thought to do some research on it and write a Blog. Cybertec (One of The PostgreSQL Database Company) has released a PostgreSQL Module ODBC Link, using which user can make Database link to any other database, including Oracle, MS SQL Server, PostgreSQL etc, which have ODBC compliant Data source. Lets see how you can make ODBC Connection from PostgreSQL to any ODBC compliant data source and fetch data. Installation of this module is very simple. Following are the steps which user can follow: 1. Install the unixODBC driver on your linux machine. user can use following useful link for Downloading and Installing the unixODBC Driver: http://www.unixodbc.org/ 2. Download ODBC-Link from following location: http://www.cybertec.at/download/odbc_link/ODBC-Link-1.0.4.tar.gz 3. Untar the downloaded file as given below: tar -zxvf ODBC-Link-1.0.4....
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