disadvantages of nosql

transactions in the database (transaction) have ACID4 basic features that can be compared to trading:1,A (atomicity) atomicityEverything in the transaction is either completed or failed during execution and is rolled back.2,C (consistency) ConsistencyThe database should be in a consistent state.For example: Existing integrity constraints a+b=10, if a transaction changes A, then B must be changed3,I (isolation) IndependenceThe concurrent transactions do not affect each other.If the data to be acc

transactions, but also does not support the associated query , why? Because the associated query requires other nodes to provide data sharding , one query needs to mobilize other nodes, so concurrency performance will be very poor.This kind of lightweight distributed database system, which can only guarantee weak consistency, is a NoSQL system , which removes the correlation.NoSQL is the most used when the number of key-value storage, of course, ther

Although SQL database is a very useful tool, the monopoly is about to be broken after 15 years of a single show. This is only a matter of time: forced to use relational databases, but eventually found to be unable to adapt to the needs of the numerous.But the difference between NoSQL databases is far more than two of the differences between SQL databases. This means that the Software architect should choose a suitable

table, usually according to the user to the table, will be the same user all the data are placed on the same machine, but if we create time to query, want to query all the users in the journal published today, then this will be invalidated. At this point you need to go to each of the sub-table query and then the query results are assembled. And the native SQL is not complete. When an index is unavailable, the aggregation operation is certainly not allowed. SQL or NoSQLSo you can see that SQL is

Guide: Kristóf Kovács is a software architect and consultant who recently published an article comparing various types of NoSQL databases . The article is compiled by Agile translator – Tang Yuhua . For reprint, please refer to the following statement.Although SQL database is a very useful tool, the monopoly is about to be broken after 15 years of a single show. This is only a matter of time: forced to use relational databases, but eventually found to

This article was reproduced from: http://coolshell.cn/articles/7270.html ================================================ Full-text translation from the wall of the article "NoSQL Data Modeling techniques", translation is not good, please forgive me. After reading this article, you may feel a little bit about NOSQL data structures. My feeling is that the relational database wants to do a good job of consist

Recently, the company is making a NoSQL model selection, and has made the following Rough Analysis and Comparison on several common NoSQL databases over a week. Recently, the company is making a NoSQL model selection, and has made the following Rough Analysis and Comparison on several common NoSQL databases over a week

Oracle Releases NoSQL Databases Oracle, as the world's largest relational Database provider, has also joined the NoSQL Database chain in its product chain. In addition, this new Database name is so domineering that it is called NoSQL Database, I think of a joke about Sina Weibo's changing weibo.com Domain Name: Three family members made bread, three family me

Recently I am reading nosql. A major advantage of nosql over relational databases is high availability. Therefore, some questions are raised: Why does nosql achieve high availability while relational databases suffer from criticism in this regard? Relational Database Service Oracle and sqlserver are both distributed databases. Definition of distributed

[It168]Nosql was originally abbreviated as not SQL, and has now evolved into not only SQLBecause developers have realized that, in fact, those who prefer SQL and those who have a lot of SQL experience are moreProgramThe cost of employee employment is lower, and such a person is more likely to be recruited. In fact, it is an error that nosql does not use SQL. SQL is not used because of poor performance, bu

With the development of Internet technology, the traditional relational database can not be satisfied with the storage and analysis of massive data, thus deriving a database NoSQL (not only SQL) which is different from the relational database.The more mature nosql in foreign countries have mongodb,cassandra,tokumx and so on, not listed.As far as I know, bat and other giants have their own

Tags:xml recommended orm high concurrency hardware and software Conditions Ecology Database Tables deployment Not in any scenario, NoSQL is superior to relational databases. Let's talk a little bit about when to use NoSQL to compare power:1) database table schema changes frequentlyFor example, the online store, the maintenance of product properties often to increase the field, which means that the orm

The scalability of the system is the main reason for the development of the NoSQL movement, including distributed system coordination, failover, resource management and many other features. That makes NoSQL sound like a big basket, and everything can be plugged in. Although the NoSQL movement does not bring fundamental technological changes to distributed data pr

replication, and can be used with Replica sets to achieve Sharding + fail-over, and load balancing between different Shard. The query is transparent to the client. The client performs query, statistics, MapReduce, and other operations. These operations are automatically routed to the backend data node by MongoDB. This allows us to focus on our own business, which can be easily upgraded when appropriate. MongoDB's Sharding design capability can support up to 20 petabytes, which is sufficient to

data set query.④ built-in sharding.Provides a range-based auto sharding mechanism: A collection can be divided into several segments according to the range of records, to be segmented onto different shard.Shards can be combined with replication, with replica sets can achieve Sharding+fail-over, different shard can load balance. The query is transparent to the client. The client performs queries, statistics, and mapreduce operations, which are automatically routed by MongoDB to the backend data

tolerance) (loss or failure of any information in the system will not affect the continued operation of the system) The core of the CAP theory is that a distributed system cannot meet the three requirements of consistency, availability, and partition fault tolerance at the same time, and can only satisfy two at the same time. Therefore, according to the CAP principle, the NoSQL database is divided into three categories: satisfying the CA princi

NoSQL-monodb installation use official download monodb: www. mongodb. orgdownloads to download Windows32-bit for example, 32-bit version of MongoDB is suitable for testing and evaluation purposes only, only support less than 2 GB of database. Set environment variables: extract the environment variables to the installation directory, rename them, and change the binfile directory to the system environment. NoSQL