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Note (6): Can be implemented using Function-based Indexes in Oracle 8i and higher, but the function needs to be used in the sql for the index to be used. Note (7): A PostgreSQL functional index can be used to reverse the order of a field. Note (10): B+ tree and full-text only for now.
mongodb.com. MongoDB is a source-available, cross-platform, document-oriented database program. Classified as a NoSQL database product, MongoDB utilizes JSON -like documents with optional schemas. MongoDB is developed by MongoDB Inc. and current versions are licensed under the Server Side Public License (SSPL).
NoSQL. NoSQL (originally referring to "non- SQL " or "non-relational") [1] is an approach to database design that focuses on providing a mechanism for storage and retrieval of data that is modeled in means other than the tabular relations used in relational databases. Instead of the typical tabular structure of a relational database, NoSQL ...
Document-oriented databases are one of the main categories of NoSQL databases, and the popularity of the term "document-oriented database" has grown [2] with the use of the term NoSQL itself. XML databases are a subclass of document-oriented databases that are optimized to work with XML documents. Graph databases are similar, but add another ...
The standard relational algebra and relational calculus, and the SQL operations based on them, are unable to express directly all desirable operations on hierarchies. The nested set model is a solution to that problem. An alternative solution is the expression of the hierarchy as a parent-child relation. Joe Celko called this the adjacency list ...
An SQL select statement and its result. In computing, a database is an organized collection of data or a type of data store based on the use of a database management system (DBMS), the software that interacts with end users, applications, and the database itself to capture and analyze the data. The DBMS additionally encompasses the core ...
The third normal form (3NF) is a normal form used in database normalization. 3NF was originally defined by E. F. Codd in 1971. [2] Codd's definition states that a table is in 3NF if and only if both of the following conditions hold: The relation R (table) is in second normal form (2NF). No non-prime attribute of R is transitively dependent on ...
Schemas. [edit] PostgreSQL schemas are namespaces, allowing objects of the same kind and name to co-exist in a single database. They are not to be confused with a database schema -- the abstract, structural, organizational specification which defines how every table's data relates to data within other tables.