Venetian source Building and NoSQL Introduction

NoSQL (not only SQL), meaning "not just SQL," is a new revolutionary movement in the database, which was raised early on, and the trend grew even more in the 2009. NoSQL advocates are advocating the use of non-relational data storage, which is undoubtedly a new kind of thinking injection, relative to the overwhelming use of relational databases. Venetian source building qq:2152876294 URL diguaym.com

Four categories of NoSQL databases
(1) key value (key-value) Storage database

This type of database primarily uses a hash table that has a specific key and a pointer to the specific data. The advantage of the Key/value model for IT systems is simplicity and ease of deployment. But if the DBA only queries or updates part of the value, Key/value becomes inefficient. Examples include: Tokyo cabinet/tyrant, Redis, Voldemort, Oracle BDB.

Typical scenario: Content caching, which is used primarily for high-access loads that handle large amounts of data, as well as some log systems, and so on.

Data model: Key value pair that key points to value, usually using hash table to implement

Pros and Cons: Fast lookup, unstructured data, usually only as string or binary data

(2) The column stores the database.

This part of the database is often used to deal with massive amounts of data for distributed storage. Keys still exist, but they are characterized by pointing to multiple columns. These columns are arranged by the column family. such as: Cassandra, HBase, Riak.

Typical application scenario: Distributed File Systems

Data Model: Store the same column of data together in a clustered type

Advantages and Disadvantages: Fast lookup, strong scalability, more easily distributed extension, function is relatively limited

(3) Document type database

The document database is inspired by Lotus Notes Office software and is similar to the first key-value store. This type of data model is a versioned document, and semi-structured documents are stored in a specific format, such as JSON. A document database can be considered an upgraded version of a key-value database, allowing for the nesting of key values. and the document database is more efficient than the key-value database query. such as: CouchDB, MongoDb. Domestic also has the document type database SEQUOIADB, already open source.

Typical scenario: Web applications (similar to Key-value, value is structured, but the database is able to understand the content of value)

Data model: Key-value corresponding key-value pairs, value is structured data

Advantages and Disadvantages: The data structure requirements are not strict, the table structure is variable, do not need to be like a relational database need to define the table structure, query performance is not high, and the lack of unified query syntax.

(4) Graph database (graph)

The graphical structure of the database is different from the other columns and the rigid structure of the SQL database, it is using a flexible graphical model, and can be extended to multiple servers. NoSQL databases do not have a standard query language (SQL), so database queries require a data model. Many NoSQL databases have rest-type data interfaces or query APIs. such as: neo4j, Infogrid, Infinite Graph.

Typical application scenarios: social networks, referral systems, and more. Focus on building a relationship map

Data Model: Graph structure

Advantages and disadvantages: Using graph structure correlation algorithm. such as the shortest path addressing, N-degree relationship lookup, and so on, many times need to calculate the entire graph to obtain the information needed, and this structure is not very good for distributed cluster scheme.

Venetian source Building and NoSQL Introduction