Oracle licenses it's RDBMS by several factors, typically the Standard License (by socket) and an Enterprise License (by core scaling factor.) Occasionally, hardware and operating system vendors will enhance their offerings, requiring a revisit by database vendors to expand their legal categorizations for licensing. Oracle's guiding documents are readily available on-line.
Reason for Revisit:
A fairly extensive set of documents were posted over the past few years, but the URL's to these documents have changed, roughly since the acquisition of Sun by Oracle. Those core documents are listed below with why one might need to reference them.
Software Investment Guide
The Oracle Software Investment Guide is perhaps the most thorough document on performing Oracle installations within an organization. Perhaps these few sentences from the guide best describes what it contains.
We provide a detailed overview on how to license all Oracle products, from the Oracle database platform and application server to all Oracle enterprise applications, which includes Oracle E-Business Suite, Siebel, PeoplSoft, and JD Edwards.This guide is clearly not isolated to merely Oracle Databases, but it is an authoritative source.
Nine easy-to-read sections enable you to find the topics that interest you most. Within every section, each specific topic has hyperlinks and toll free numbers that enable you to get more information on the subject matter.
Additionally, we've included illustrations to enhance your understanding of our pricing practices related to data environments, batch processing, and more.
Pricing information on Oracle services, such as Support, Outsourcing, Consulting, and Education is also here.
Oracle regularly updates their Database Licensing guideline document. Terminology such as Test, Production, Sockets, and Processors are defined within this document. Finer details which are often commonly asked questions include: development databases are normally no charge, but test and production databases must be purchased; Oracle Standard Editions may be charged by socket, but more advanced features means per-processor or per-user licensing must occur with Oracle Enterprise Edition; when dealing with IBM & Intel CPU's, "each chip in the multi-chip module is counted as one occupied socket."
Oracle regularly updates their Server/Hardware Partitioning document, as system vendors create new technologies. Rigorous vendors create technologies categorized under "Hard Partitioning" (i.e. Capped Solaris Containers) while less rigorous vendors often create "Soft Partitioning" technologies (i.e. VMWare.) Some virtualization technology can be implemented as both Hard or Soft Partitioning, so implementation details must be attended to (i.e. Oracle VM implementation notes.) Costs can be controlled through careful architecture decisions, if one understands how a "Processor" is counted in such virtual environments.
Processor Core Factors:
Oracle regularly updates their Processor Core Factor Table, as new CPU designers release new central processor units. Certain multi-core CPU sockets with close throughput but vastly different core counts often have very different pricing (i.e. 16 core SPARC T3 "0.25" vs 8 core SPARC T4's "0.50" factor.)
Commercial Price List:
Oracle's standard Commercial Technology Price List which includes the database packages, is also published in PDF. While this price list changes regularly, Oracle specifies the retail pricing for databases such as: Standard Edition One, Standard Edition, Enterprise Edition, additional add-on components, etc.
It would be wise to track these changes to these documents, as new purchases are required, and new architectures are being developed.