NoSQL MongoDB Simple installation and command use

NoSQL: Non-relational, distributed, acid-not-available

Simple Data Model

Separation of metadata and application data

Weak consistency

Advantage:

Avoid unnecessary complexity

High throughput

High level of scalability and low-end hardware clustering

Do not use object-relational mappings

Disadvantage:

ACID Properties Not supported

Simple function

No unified data Query model

Acid:atomicity Atomicity, consistency consistency, isolation isolation, durability persistence

NoSQL Categories:

Column database (column-managed)

Key-Value Storage

Document database (each line as an entity, separate file)

Survival database (Survival object with complex relationships), used in social sites to store complex relationships between people

A NoSQL data storage model

Column database (column-managed)

Data model: Data is stored by column, with the same column of data

Advantages: Fast lookup, strong scalability, easy to implement distributed

Cons: Limited functionality vs. sql

Application scenario: Distributed File system or distributed storage

Examples: BigTable, Cassandra, HBase, hypertable (mass data storage)

running on a distributed file system

Key-value Storage (Data model: Key-value storage)

Pros: Find Fast

Cons: Data is unstructured and is usually used only as a string or binary data

Application Scenario: Content Caching

Example: Redis, Dynamo

Document database (each line as an entity, separate file)

Data model: Similar to a key-value model, but value points to structured data, with a container attached to multiple key-value pairs

Pros: Data format requirements are not stringent, no need to define the structure beforehand

Adding a field does not require a change in its data structure

Disadvantage: Query performance is not high lack of unified query syntax

Application Scenario: Web App

Example: MongoDB, CouchDB

Survival database (Survival object with complex relationships), used in social sites to store complex relationships between people

Data Model: Graph structure Model

Advantages: The use of graph structure-related algorithms to provide performance, and full of special scenarios application requirements

Cons: Difficult to achieve distributed, functional and directional

Application scenarios: social networks, referral systems, relational maps

Example: neo4j

Mongodb:scalable (extensible) high-performance (high performance) Open source schema free document NoSQL

Schema free: No data structures need to be created beforehand

Read and write in memory

Support Extensibility: replication, Automatic sharding

Applies To: Web site, cache, high scalability, HI Volume,low value

MongoDB installation: It is recommended to install with RPM package

RPM Package Address: Https://repo.mongodb.org/yum/redhat, choose your own version to download

Yum-y Localinstall *.rpm

Mkdir-p/mongodb/data: Create a data directory, modify the data directory path in the configuration file

usermod-d/mongodb/data Mongod

Chown-r Mongod:mongod/mongodb/data: Modifying the genus Group of the data directory

Finally, a simple modification of the configuration file information (data directory, log directory, etc.)

Finally, you can start Mongod.

Service Mongod Start

To view the log records, the following warning is found:

Cat/var/log/mongodb/mongod.log View Log, error is as follows:

* * Warning:soft rlimits too low. Rlimits set to 1024x768 processes, 64000 files.

Number of processes should is at least 32000:0.5 times number of files.

Reference: http://blog.csdn.net/kk185800961/article/details/45613267

Current limitations of MongoDB: Processes, 64000 files

MongoDB Recommended Requirements: Processes = 0.5*files=32000 (at least)

So you need to change the processes from 1024 to 32000 or greater.

To modify the configuration file/etc/security/limits.conf, add the configuration information:

############## #for mongodb##############

Mongod Soft Nofile 64000

Mongod Hard Nofile 64000

Mongod Soft Nproc 32000

Mongod Hard Nproc 32000

Then restart the Mongod, review the log record again, found no warning, so the installation of MongoDB succeeded

MongoDB's Simple Grud operation:

>help (View Help)

Db.help () Help on DB methods

Db.mycoll.help () Help on collection methods

Sh.help () sharding Helpers

Rs.help () Replica set helpers

Help Admin Administrative Help

Help connect connecting to a DB help

Help keys key shortcuts

Help Misc Misc Things to Know

Help Mr MapReduce

Show DBS Show Database names

Show collections show collections in current database

Show users show users in current database

Show profile Show most recent system.profile entries with time >= 1ms

Show logs show the accessible logger names

Show log [name] prints out the last segment of log in memory, ' global ' is default

Use <db_name> Set current database

Db.foo.find () List objects in collection Foo

Db.foo.find ({a:1}) List objects in Foo where a = = 1

It result of the last line evaluated; Use to further iterate

dbquery.shellbatchsize = X Set default number of items to display on shell

Exit quit the MONGO shell

View All galleries: Show DBS

View all collections (in MySQL is a table, in MongoDB with collections): Show collections

Switch Library: Use HUANGDB (no need to define it before, just take it to the library.)

Inserting data into the collection Huangcoll: Db.huangcoll.insert ({Name: "Huang"})

View the collection's data: Db.huangcoll.find (): This is all the data that is viewing the collection Huangcoll

Find data by criteria: Db.huangcoll.find ({Name: "Huang"}): Find documents with Name Huang

CREATE INDEX: Db.huangcoll.ensureIndex ({name:1}): Create index for field Name

View index: Db.huangcoll.getIndexes (): View all indexes under the current collection

For more MONGO command operations, refer to the documentation:

https://docs.mongodb.com/manual/crud/

NoSQL MongoDB Simple installation and command use