Oracle RDBMS

Oracle database is a relational DBMS that has extended the relational model to an object-relational model, to store business models in an RDBMS. Database Schema: Database schema is a collection of logical data structures Table: It represents the real-world entity and can have integrity constraints on columns Index: Data Access: Structured Query Language (SQL): Oracle RDBMS uses PL/SQL which is an extension which helps store application logic in the DB itself Transaction Management: Oracle RDBMS supports multiuser concurrency. Transaction: Data Concurrency: Oracle RDBMS enforces a statement-level and transaction-level read consistency. This is done to avoid the dirty read problem and based on the level of consistency, DBMS guarantees data returning from the single or multiple queries is consistent and committed. Oracle RDBMS is a set of physical structures like files and applications inside a single physical database can interact with multiple logical databases.

Oracle RDBMS has multitenant architecture, Sharding Architecture: Partition horizontally across multiple physical Oracle RDBMS. Useful for OLTP applications. After sharding, every database(shard) has a dedicated server and resources - CPU, flash, disk and memory and together they make up a single logical database.

Database Storage Structures : Physical Storage Structures: Files storing data on the disk Data files: Oracle RDBMS stores data for logical database structures on physical files Control files: Contains metadata about the physical structure of the database like file locations Online redo log files: consists of redo entries that record changes made to data Local Storage Structures : Data blocks: it represents the number of bytes on disk Extent: number of continuous logical data blocks in a single allocation Segments: number of extents allocated for an object like table or index Tablespaces: a logical container for segments Oracle RDBMS Processes: Client processes, background processes, server processes

History

In 1977, Larry Ellison, Robert Miner, and Ed Oates founded Software Development Laboratories, which was hired by the United States Central Intelligence Agency (CIA) in order to write a new database system based upon SQL. This system came to be known as Oracle. The company changed its name to Relational Software, Inc. in 1979 and then to Oracle Systems Corporation in 1982.

Isolation Levels

Read Committed Serializable

Oracle supports isolation levels of read committed as well as serializable, defaulting with the latter. There is an additional mode available, "read only", which is not part of the SQL standard.

Data Model

Relational Key/Value Document / XML Graph

Oracle was originally designed as a relational DBMS. It now also supports a variety of data models for storage.

System Architecture

Shared-Everything

Compression

Naïve (Page-Level) Naïve (Record-Level) Bit Packing / Mostly Encoding

Oracle supports compression at multiple levels within the data, including by row, block, and index. It also supports network compression designed to reduce bandwidth usage and increase network throughput.

Storage Organization

Heaps

Oracle RDBMS Logo
Website

http://www.oracle.com/us/products/database/

Tech Docs

https://docs.oracle.com/en/database/oracle/oracle-database/index.html

Developer

Oracle

Country of Origin

US

Start Year

1977

Project Type

Commercial

Written in

C, C++

Supported languages

C, C++, COBOL, Java, PHP, PL/SQL, Python, R, SQL, Visual Basic

Operating Systems

AIX, HP-UX, Linux, Solaris, Windows

Licenses

Proprietary

Wikipedia

https://en.wikipedia.org/wiki/Oracle_Database