MongoDB Learning Notes

1. MongoDB is an open-source, document-oriented (not relational-oriented) non-SQL database that is written in C + + and is one of the most popular NoSQL databases today.

2. MongoDB adds not structured data (table structure, pre-defined table structure), but is described by each piece of data itself, it wraps it into a JSON-like format called Bson, which is extended from the JSON, packaged like this {"UUID": 1, " UserID ":" U1 "} Key:value, which is called a document in MongoDB, is meant for documentation.

3.NOSQL Introduction

NoSQL means more than just SQL, which is the generic term for the "non-relational database" that is currently popular. Common NoSQL databases such as: Redis, CouchDB, MongoDB, HBase, Cassandra

4. {"UUID": 1, "userid": "U1"} This is OK, {"UUID": 1, "userid": "U1", "name": "Ansong"} This can also be very casual in nosql.

5. The need for high concurrency and read-write requirements for databases, the need for efficient storage and access to massive volumes of data, and the need for high scalability and high availability of databases

6.CAP theorem, Brewer's theorem, the distributed system can not meet the following three points: strong consistency, availability, partition fault tolerance

7.nosql Advantages: ① extension is simple and convenient, especially horizontal scale-out (vertical expansion means: stronger machine; landscape: Data spread to multiple machines), ② Read and write fast and efficient, most maps to memory operation ③ Low cost, with ordinary machine, distributed cluster is good ④ data model flexible, no fixed data model

8. Cons: SQL not supported, existing products (09 start) Immature and stable, function still need to be strengthened

9.MongoDB is just one of the NoSQL, document-oriented, high-performance, easy-to-use extensions for collection storage, mode freedom, support for dynamic querying, support for JS expression queries, support for indexing, support for replica set replication and automatic failback, support for automatic processing of shards, support for binary and large object data, Support for storage format bson (extension of JSON)

10.

MongoDB Learning Notes