preface_2.htm
Disclaimer:

This document is a brief collections of information available through old published books and internet; I did not have chance to check all cross references to validate  the time lines.

As a personal bias I was more curious about PostgreSQL database; I learned Oracle database first then others. Therefore, I reviewed Oracle's organizational history than structural nut-bolts.

Here I document my inclinations towards these databases only, than be a critique of any system or application.   

 
Oracle: "The Oracle Database (commonly referred to as Oracle RDBMS or simply as Oracle) is an object-relational database management system produced and marketed by Oracle Corporation."

1970s-Assembly Language , SDL To RSI

Larry Ellison with Bob Miner and Ed Oates of Software Development Laboratories (SDL) started Relational Software Inc, where Oracle precursor was written in assembly language. Oracle version 1 was not released officially, Oracle version 2 was released around 1979

1980s  RSI to Oracle Systems Corporation

Oracle version 3 was developed with C programming language, and to run in mainframe and mini computers. It supported the execution of SQL statements and transactions. The version 5 was the land mark of introducing clustering , and in 1986 SQL*Plus was available to the users. The PL/SQL surfaced with the version 6.

1990s and 2000s: Oracle releases

Oracle 7, Oracle 8, 8i, 9i were release. As a landmark Oracle 7 revisions,  supported dynamic SQL Video, the version 8 started supporting Java, HTML and network computing, the version 9i RAC surfaced.

Oracle release 10g was released supporting Linux 64bit, (g stands for grid computing) in which resource of each computer in a network could be accessible through one lead computer often addressed as "Node".

Data Block : Oracle manages the storage space in the datafiles of a database in units called data
blocks. A data block is the smallest unit of data used by a database. Oracle stores datafiles in data block (logical block or pages), requests multiple datablock of it's own, not the ones managed by operating systems. A specific number of blocks constitutes an extent, set of extents constitute a segment.
 
PostgreSQL: is an object-relational database management system (ORDBMS). It is ACID-compliant, supports transactional (including most DDL statements) avoiding locking issues using Multiversion Concurrency Control (MVCC), provides strong protection against data-corruptions. (ref: postgresql-9.3-A4.pdf)

1970s-Ingres-RDBMS

PostgreSQL as a database has a long history. In the late 1970s, the University of California at Berkeley started  a created of a relational database known as Ingres. Relational Technologies commercialized this DB as Ingres. Relational Technologies became Ingres Corporation, and was later acquired by Computer Associates.

1980s-Ingres To Postgres
 A team led by Michael Stonebraker from UC Berkeley led, added object-oriented features to Ingres and named as Postgres. Postgres was then commercialized; by Illustra, which became a part of the Informix Corporation.

1990s-Postgres To PostgreSQL

Postgres used a specific query language known as Postquel, which was based on QUEL. Andrew Yu and Jolly Chen added SQL support to the existing  Postgres database in the mid-'90s.  In 1996, many new features were added, including the MVCC transaction model, more adherence to the SQL92 standard, and many performance improvements. Postgres once again acquired a new name, PostgreSQL.
PostgreSQL: It Was then

The older versions of PostgreSQL, you could run the PostgreSQL server on a Windows host but you had to install a Unix-like infrastructure (Cygwin) first: PostgreSQL wasn't a native Windows application. Starting with PostgreSQL version 8.0, the
PostgreSQL server has been ported to the Windows environment as a native-Windows application.

Before PostgreSQL 8.0, PostgreSQL server was required to have Unix-like infrastructure (Cygwin) in windows. The version 8.0 and onwards, PostgreSQL can be installed in windows environment.
 
Useful ref: