data and safe . two. Non-relational database ( NOSQL):in order to deal with large amounts of data , the relationship between relational database needs to be removed. the initial design of non-relational
read consistency, rollback segment mechanism are all important mechanisms to ensure read consistency. Isolation: As for isolation, the book says that "when different transactions operate on the same data, each transaction has its own working space". I understand that when different times come to operate the same data, only one transaction is exclusive, and the other transaction can only wait for the exclusive transaction to execute commit or rollback. Later, I thought, the author called the "
Label:In the past, we only needed to learn and use a database technology to do almost all of the database application development. Because the mature and stable relational database products are not many, and for you to choose the free version is even less, so the Internet domain basically chose the free MySQL
Tags: and EXT structure Publishing NAT process name Data Model operationsThe SQL (Structured Query Language) database is the primary way to store data over the past 40 years. The late 1990s with the rise of Web applications and open-source databases such as MySQL, PostgreSQL, and SQLite, the explosion of user growth. NoSQL databases have been in existence since the 1960s and have gained more attention until
Advantages and disadvantages of relational databaseAdvantages:
Can do transaction processing, so as to ensure the consistency of data;
Can be a join, such as multi-table query;
Because of SQL standardization, the cost of data updates is small (the same fields are basically only one place).
Disadvantages:
The write processing of large amount of data is not easy;
If the table data volume is too large, it is not easy to do index or
NoSQL systems generally advertise a feature, that is, good performance. Why? After so many years of development in relational databases, various optimizations have been done very deeply. NoSQL systems generally use relational database technology. What factors have bound the
large-scale SNS website, the daily user generates a huge amount of user dynamics, taking foreign friendfeed as an example, one months to reach 250 million user dynamics, for the relational database, in a 250 million records of the surface of the SQL query, the efficiency is extremely low even intolerable. 3. High Scalability hi availability-requirements for database
Basic concepts of one or two peopleNoSQL, which refers to non-relational databases.Relational database is a database based on the relational model.The relational model is mentioned here,The relational model was proposed by E.f.cod
method is not not possible, but in the actual use of each time repeated table structure changes is very painful. You can also preset a large number of pre-fields, but in this case, it is easy to get rid of the corresponding state of the field and data, that is, which field holds the data.--the processing of a simple query that requires a quick return of results ("simple" here refers to the absence of complex query conditions)This is not a disadvantage, but in any case, the
Label:1. Relational databaseRepository for permanent data storagePHP variables are only temporary storage space "use memory space" to save variables during PHP script execution.Relational database: Use the relationship between the two to describe the entity information. "Using two-dimensional table field names and fields values to describe""Relational databases a
relational databaseAdvantage:1. Good at handling small data volumes2. Good at complex SQL operations, can make complex queries such as joins3. Can easily generate a variety of data objects, the use of stored data to build forms and reports, the visibility of goodDisadvantage:1. It is difficult to write processing for distributed applications and large amounts of data2. Indexing and structural changes to tables with data updates3. Application with Fiel
; Redis-cliredis 127.0.0.1:6379> Set Password Abcdefokredis 127.0.0.1:6379> Get Password "abcdef" Redis 127.0.0.1:6379> quitshell > kill-9 ' cat/usr/local/ Redis/logs/redis.pid '# # When Redis is not turned off normally, such as kill-9, Redis server sudden outage, etc.ls /usr/local/redis/data/# # is not synchronizing the in-memory data to disk, which means that the Dump.rdb file is not generatedShell > redis-server/usr/local/redis/> redis-127.0. 0.1:6379>127.0. 0.1:6379> quit# # then start Redis
1. Master-slave replication is MongoDB The most commonly used replication method, which is very flexible and can be used for backup, failure recovery, read extension, etc.2 The most basic way to set up is to establish a master node and one or more slave nodes, each from the node to know the address of the master node. The primary server is started by running Mongod–master. Running mongod–slave–source master_address initiates the slave server, where master_address is the address of the prima
Some basic usage MySQL and MongoDB design instance comparison: http://www.51testing.com /? Uid-116228-action-viewspace-itemid-241061
MongoDB common methods: http://blog.csdn.net/cppbegginer/article/details/6968522
MongoDB database installation and PHP connection test on Windows: http://hi.baidu.com/zyrym1989/blog/item/60f9154fb1df84d5d0c86ab0.html
MongoDB advanced query: http://www.cnblogs.com/cxd4321/archive/2011/06/24/2089057.html
MongoDB + MySql F
Tags: Mongo lan mon min idt dex font Use admin One: Normal index 1 to create a new database > Use Toto; Switched to DB Toto > Show DBS; Admin (empty) Local 0.078GB > Use Toto; Switched to DB Toto > DB Toto > 2 Create - million-piece data > for (var i=1; I ... db.c3.insert ({name: "Zhangsan", age:i}); ... } >db.c3.count (); 3 No index lookup >db.c3.find ({age:500000}). Explain (); 4 bit Age field to create an index Db.c3.
Tags: empty god name for Sys + + ... lang csdn?? One: Normal index 1 to create a new database > Use Toto; Switched to DB Toto > Show DBS; Admin (empty) Local 0.078GB > Use Toto; Switched to DB Toto > DB Toto > 2 Create - million-piece data > for (var i=1; I ... db.c3.insert ({name: "Zhangsan", age:i}); ... } >db.c3.count (); 3 No index lookup >db.c3.find ({age:500000}). Explain (); 4 bit Age field to create an index Db.c3.en
A general introduction to NoSQLHttp://www.apelearn.com/bbs/forum.php?mod=viewthreadtid=8660highlight=NoSQLmemcached Introduction1.3 memcached InstallationHttp://www.apelearn.com/bbs/thread-9285-1-1.htmlYum Install-y epel-releaseRpm-qa Epel-releaseYum install-y livevent memcached libmemcached/etc/init.d/memcached startNetstat-lnpPS aux |grep memcachedVi/etc/init.d/memcachedCat/etc/sysconfig/memcached-L Listener Server IPMemcached-tool 127.0.0.1:11211 StatsMemStat--servers=127.0.0.1:112111.4 memca
storage (disk space) is negligible. While non-relational data is stored in a flat dataset, data can often be duplicated. A single database is rarely separated, but stored as a whole, so that it is easier to read and write for the whole piece of data. Vertical Expansion vs Horizontal expansion The biggest difference between SQL and NoSQL databases may be in scali
relational databases and NoSQL databases what is NoSQLHave you ever heard of "NoSQL"? In recent years, this word has been of great concern. To see the word "NoSQL," you might mistakenly think it was "no! SQL "abbreviation, and deeply outraged:" How can SQL be unnecessary? " "But in fact, it is the abbreviation for" not
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