Database Technologies: Some trigger and programming feature in PostgreSQL

Database Technologies: Some trigger and programming feature in PostgreSQL

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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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New in PostgreSQL 9.3: Server Side languages

In series of blogging about new features coming in PostgreSQL 9.3, I thought to blog about the server side language improvements in PostgreSQL. Lets see whats coming in server side language. As PostgreSQL user, you know, PostgreSQL supports multiple server side language. In 9.3, there are some interesting features are coming. Lets look at the new improvements about to come. 1. SPI access to number of rows processed by COPY command. This is more like new feature which is introduced in 9.3. Before 9.3, this feature was missing. i.e if user uses COPY command inside the plperl/plpython functions, then there was no way inside the procedure to trace the number of rows processed by COPY. However in 9.3, this limitation is no more exists with procedural language. There are many languages supported in PostgreSQL, However I chose to test this with mostly used language plperl and plpython. Below are some snapshot pre-9.3 and in 9.3. Lets check with plperl. Following is a plperl function w...
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