Oracle AI Database (commonly referred to as Oracle Database, Oracle DBMS, Oracle Autonomous Database, or simply as Oracle) is a proprietary multi-model database management system developed and marketed by Oracle Corporation. First released in 1979, it was among the earliest commercially available databases to use SQL. It is commonly used for online transaction processing (OLTP), data warehousing (DW), and mixed database workloads. As a converged database, it supports multiple data models within a single engine, including relational, JSON document, XML, spatial, graph, text, and AI vector data, all queryable through SQL or APIs. Oracle AI Database runs on-premises, on Oracle engineered systems such as Oracle Exadata, on Oracle Cloud Infrastructure, and as a managed Autonomous Database service. It is also offered inside Microsoft Azure, Google Cloud, and Amazon Web Services data centers through Oracle's multicloud offerings. The current long-term release is Oracle AI Database 26ai, which was introduced in October 2025.
History Larry Ellison and his two friends and former co-workers, Bob Miner and Ed Oates, started a consultancy called Software Development Laboratories (SDL) in 1977, later Oracle Corporation. SDL developed the original version of the Oracle software. The name Oracle comes from the code-name of a Central Intelligence Agency-funded project on which Ellison had worked while employed by Ampex; the CIA was Oracle's first customer, and allowed the company to use the code name for the new product.
Growth and the internet era Oracle Corporation held its initial public offering on March 12, 1986. The company grew rapidly during the 1980s, though a financial setback in 1990 led to its first quarterly loss and significant layoffs before the business recovered.
Clustering, grid, and cloud computing Oracle Database 12c introduced multitenant architecture in 2013. Database In-Memory, including the In-Memory Column Store, was introduced in Oracle Database 12c Release 1 version 12.1.0.2. Oracle announced Oracle Autonomous Database in 2017, with the first services becoming available in 2018. Beyond the on-premises editions, Oracle Autonomous Database automates provisioning, tuning, patching, and scaling and is offered in data-warehousing and transaction-processing variants.
Architecture
Instances and databases An Oracle AI Database system consists of an instance and a database. The instance is a set of memory structures and background processes; the database is the set of files that store data. An instance exists only in memory, and in the multitenant configuration a single instance is associated with one container database. Client programs connect to the database through server processes, established by way of the Oracle Net listener.
Memory The principal memory structures are the System Global Area (SGA), shared by all server and background processes, and the Program Global Areas (PGA), which are private to individual processes. The shared pool, database buffer cache, and redo log buffer are components of the SGA, and the optional In-Memory Column Store also resides there. Each PGA holds session information and the work areas used to process SQL statements.
Processes Background processes operate on the database files and use the memory structures to do their work. They include the database writer, the log writer, the checkpoint process, the system monitor and process monitor processes, and the archiver processes that copy redo logs for recovery. Server processes handle connections from client programs and run their SQL statements.
Storage structures Storage is organized both logically and physically. Logically, data is held in tablespaces composed of segments, extents, and data blocks. Physically, the database comprises data files, control files, and online redo log files, with archived redo logs supporting media recovery. Data files can be placed on conventional file systems or managed by Automatic Storage Management (ASM), a volume manager and file system built into the database.
Multitenant architecture
Oracle Database 12c introduced the multitenant architecture, based on container databases (CDBs) and pluggable databases (PDBs). A CDB contains a root container (CDB$ROOT) that holds Oracle-supplied metadata and common users, a seed PDB (PDB$SEED) used as a template for creating new PDBs, and zero or more user-created PDBs. Beginning with Oracle Database 21c, the multitenant container database is the only supported architecture; earlier releases also supported non-container (non-CDB) databases. A PDB appears to a client or application as an independent database, while from the operating system's perspective the CDB is the database. Because PDBs are portable, they can be unplugged from one CDB and plugged into another, supporting database consolidation, cloning, and patching at the container level.
Concurrency and consistency Oracle Database provides multiversion read consistency, also known as consistent read. When a transaction modifies data, the database writes the previous values to undo segments, allowing earlier versions of the same data to be read without blocking ongoing writes. In Oracle’s default read-committed isolation mode, each SQL statement sees only committed data, and that data is consistent as of a single point in time when the statement began; newly committed changes from other transactions are not incrementally exposed while the statement is running. Serializable and read-only transactions extend this behavior to transaction-level read consistency, so the transaction sees data as of the time the transaction began. This model allows reads and writes to proceed without blocking one another.
… excerpt ends here. Continue reading the full article.
