World largest database works on modified PostgreSQL
According to InformationWeek [http://www.informationweek.com/news/software/database/showArticle.jhtml?articleID=207801436]
Yahoo! corporation [http://en.wikipedia.org/wiki/Yahoo!] has world busiest and largest database.
System has build for analytical purposes, and contains history of web-users behavior.
It has size: 2-petabyte, and loading about 24 billion events a day.
Engineers of Yahoo expect size increasing up to 5-petabyte by next year.
In order to compare sizes:
USA Revenue Service DB: about 150 terabyte
Ebay: overall size: 6-petabyte, size of biggest system: about 1.4-petabyte
We should understand that we are talking about DBs. Because there are data repository with much greater sizes but data in such repositories practically unaccessible for analyzes and processing.
Surely it is nice to know that it works on modified PostgreSQL [http://en.wikipedia.org/wiki/Postgresql].
PostgreSQL continues active development and prove status as best open-source RDBMS.
As we remember in 2007 year Sun Microsystems [http://en.wikipedia.org/wiki/Sun_microsystems] published
production test [http://www.spec.org/jAppServer2004/results/res2007q3/] which showed that tuned PostgreSQL performance
is very close to Oracle DB [http://en.wikipedia.org/wiki/Oracle_db]: difference only about 15%. Don’t forget about price of Oracle DB.