![]() When there is an UPDATE, PostgreSQL creates a new row and expires the old one. In PostgreSQL, each row in a table has two transaction IDs - a creation and an expiration transaction ID for the transactions that created and expired the row. Usually, the reader of the database must wait for the writer to finish and vice versa, since most database software applications rely on table-level, page-level, column-level, or row-level locking. This way, the need for read locks is eliminated. MVCC stands for Multi-Version Concurrency Control - it allows the user to make changes to the database, which will remain invisible to others until the transaction is commuted. Functions, including aggregate functions.The user can create new types of almost all the objects inside the database: Due to this fact, there are a lot of companies, which offer commercial distributions of the PostgreSQL software, alongside with the free version. ![]() PostgreSQL was licensed under the BSD license, which allows for the product to be modified and then distributed commercially. ![]() Since then, the SQL version gained huge popularity and in 1996 the project was officially renamed PostgreSQL. In 1994, two Berkeley graduates converted Postgre to use the SQL interpreter instead of the QUEL one and labeled their version Postgre95. The last version using the QUEL interpreter was released in 1993. Back then, it was not based on SQL, but on the QUEL query language. In the following years the project was completed and several versions of the Postgre database were released. The new project was based on the ideas used in Ingres, but not on its source code. However, in 1985, the leader of the Ingres project started a new, post-Ingres project, with which he aimed to address the database problems at the time. This software became the foundation of other popular database solutions, such as Sybase, MsSQL and NonStop SQL. Back then, at the University of Berkeley, California, a new database software was created - Ingres. PostgreSQL's origins lead us back to the 1970s. And as a free alternative to powerful corporate applications comes PostgreSQL. And while most of the amateur, non-professional, or open source projects use the light, quick and free MySQL databases, the professional web environments count on expensive powerful databases offering a higher level of security such as Oracle, MsSQL, Sybase. The whole content is structured, easily accessible and editable, and can be transferred or exported to another web application or a newer version of the latter. When it comes to corporate business sites the presence of databases is a mandatory element.īuilding a website which uses databases has many advantages. Dynamic content is starting to replace static content even on personal pages. True - there are many personal static web pages on the Internet working without databases, but in today's dynamic information stream static pages are archaic. Databases are indispensable when it comes to contemporary web applications.
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