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1.1 NoSQL Introduction
NoSQL(Not Only SQL), meaning Not Only SQL, refers to non-relational databases. Nosql is a technology category that has been mentioned in the early days and is gaining momentum in 2009.
Why NoSQL
With the rise of The Internet website, the traditional relational database has been unable to cope with the dynamic website, especially the pure dynamic website with large scale and high concurrency, and exposed a lot of insurmountable problems. Such as shopping mall website for commodity data frequent query, ranking statistics of hot search goods, order timeout problem, and wechat circle of friends (audio, video) storage related to the use of traditional relational database implementation is very complex, although can achieve the corresponding function but the performance is not so optimistic. Nosql is a class of technologies that solves these problems better and shows the world that there is more to it than JUST SQL.
1.3 The four categories of NoSQL
1.3.1 Key-value Storage database
1.3.1.1, description,
This type of database mainly uses a hash table with a specific key and a pointer to a specific data.
1.3.1.2, characteristics
- The advantage of the Key/ Value model for IT systems is that IT is simple and easy to deploy.
- Key/value is inefficient if the DBA only queries or updates partial values.
1.3.1.3 Related Products
- Tokyo Cabinet/Tyrant,
- Redis
- SSDB
- Voldemort
- Oracle BDB
1.3.2 Column storage database
1.3.2.1, description,
This part of the database is usually used to cope with the distributed storage of massive data.
1.3.2.2, characteristics
The keys still exist, but they are characterized by pointing to multiple columns. The columns are arranged by the column families.
1.3.2.3 Related Products
- Cassandra
- HBase
- Riak.
1.3.3 Document database
1.3.3.1, description,
The document database was inspired by Lotus Notes Office software, and it is similar to the first type of key-value store. This type of data model is a versioned document, semi-structured document stored in a specific format, such as JSON. The document database can be viewed as an updated version of the key database, allowing for the nesting of key values. And the query efficiency of document database is higher than that of key value database.
1.3.3.2 characteristics,
Store as a document.
1.3.3.3 Related Products
- MongoDB
- CouchDB
- MongoDb(4.x)
- SequoiaDB (domestic)
1.3.4 Graph Database
1.3.4.1 characteristics,
Unlike other rows and rows and rigid SQL databases, a graphically structured database uses a flexible graphical model and can scale across multiple servers.
1.3.4.2 Related Products
- Neo4J
- InfoGrid
- Infinite Graph
1.4 NoSQL Application Scenarios
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The data model is simple
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More flexible IT systems are needed
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High requirements on database performance
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A high degree of data consistency is not required
Introduction to Redis
2.1 overview,
Redis is an in-memory database
2.2 features of Redis
-
Redis is a high performance key/value in-memory database.
-
Redis supports a rich range of data types.
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Redis supports persistence.
-
Redis single thread, single process.
2.3 Redis Installation (Linux)
2.3.1 Download the Redis source package
Download direct
2.3.2 Upload and decompress
The tar - ZXVF redis - 4.0.10. Tar. GzCopy the code
2.3.3 Install the GCC
yum install -y gcc
Copy the code2.3.4 Go to the decompression directory
make MALLOC=libc
Copy the code2.3.5. Run the following command after the compilation
make install PREFIX=/usr/redis
Copy the code2.3.6 Go to /usr/redis to start the Redis service
./redis-server
Copy the code
Once this page appears, Redis is launched!
2.3.7 Go to the bin directory to connect to the client
/ reis -cli -p 6379 --raw./ reis -cli -p 6379 --rawCopy the code2.4 Details of Redis installation
Redis startup service details
/redis-server /redis-server/clone/clone/clone/clone/clone/clone/clone/clone/clone/clone/clone/clone/clone/clone Start the client in a new window./redis-cli -p 6379
How do I specify profile startup when starting Redis
By default, after reidis is installed, there is no configuration file in the installation directory. You need to copy the redis.conf configuration file from the source directory to the installation directory.
- Go to the source directory and copy the file
cp redis.conf /usr/redis
Copy the code- Go to the /usr/redis installation directory to view the replication configuration file
cd /usr/redis
ls
Copy the code- Go to the bin directory to load and start the configuration
./redis-server .. /redis.confCopy the codeThe concept of libraries in Redis
A library can store key-value pairs. In Redis, each library has a unique name (number). Starting from 0, the default number of libraries is 16, and the library number is 0-15. We can use commands to switch libraries, each library is isolated from each other, each library can have the same or different key and value, do not affect each other.
#Switch the librarySelect dbid from dbid#Clearing the current library
flushDB
#Empty all libraries
flushAll
Copy the codeEnable the Redis remote connection
- Modify the configuration file to enable remote connection
vim redis.conf
Copy the code- By default, bing 127.0.0.1 only allows native access. Change the configuration to:
#Allow all client accessBing 0.0.0.0Copy the code- Restart Redis as a configuration file
./redis-server .. /redis.confCopy the code- You can turn off Redis on the client
#(Remember there is a space before it)
hutdown
Copy the code3. Redis database related directives
3.1 Database operation instructions
3.1.1 Description of the library
The default Rsdis configuration configures the Redis service. By default, there are 16 libraries, numbered from 0 to 15. You can use the select library number to select a Rsdis library.
Seelect library numberCopy the code3.1.2 Clearing the Library
#Clear the current library
FLUSHDB
#Empty the entire library
FLUSHALL
Copy the code3.1.3 Redis client displays Chinese
./redis-cli -p 7000 --raw
Copy the code3.2 Relevant instructions of operation key
3.2.1 DEL instruction
3.2.1.1, grammar,
DEL key [key ...]
Copy the code3.2.1.2,
Deletes one or more given keys. Non-existent keys are ignored.
3.2.1.3 Return value
Number of keys to be deleted.
3.2.2 EXISTS directive
3.2.2.1, grammar,
EXISTS key
Copy the code3.2.2.2,
Check whether the given key exists.
3.2.2.3 Return value
Return 1 if key exists, 0 otherwise.
3.2.3 EXPIRE directive
3.2.3.1, grammar,
EXPIRE key seconds
Copy the code3.2.3.2,
Sets the lifetime for a given key. When the key expires (lifetime is 0), it is automatically deleted. Its time complexity is order one.
3.2.3.3 Return value
1 is returned after the setting is successful.
3.2.4. PEXPIRE directive
3.2.4.1, grammar,
PEXPIRE key milliseconds
Copy the code3.2.4.2,
This is similar to what the EXPIRE command does, but it sets the lifetime of the key in milliseconds rather than seconds as with the EXPIRE command. His time complexity is also order one.
3.2.4.3 Return value
If the key does not exist or the setting fails, 0 is returned
3.2.5. KEYS command
3.2.5.1, grammar,
KEYS pattern
Copy the codeHis pattern is a wildcard that can be matched:
- KEYS * : matches all KEYS in the database.
- KEYS h? Llo: matches Hello, Hallo, and hxLLO.
- KEYS h*llo: matches hlLO and Heeeeello, etc.
- KEYS h[ae]llo: matches hello and hallo, but not Hillo. For special symbols
"\"Separated.
3.2.5.2,
Finds all keys that match the given pattern.
3.2.5.3 Return value
List of keys that match the given pattern.
3.2.6 MOVE instruction
3.2.6.1, grammar,
MOVE key db
Copy the code3.2.6.2,
Moves the key of the current database to the given database DB.
3.2.6.3 Return value
Return 1 on success and 0 on failure
3.2.7 TTL instruction
3.2.7.1, grammar,
TTL key
Copy the code3.2.7.2,
Returns the TTL (time to live) of a given key, in seconds.
3.2.7.3 Return Value
- If the key does not exist, return -2.
- If the key exists but the remaining lifetime is not set, -1 is returned.
- Otherwise, the remaining lifetime of the key is returned in seconds.
- Prior to Redis 2.8, the command returned -1 when the key did not exist, or when the remaining lifetime of the key was not set.
3.2.8. PTTL instruction
3.2.8.1, grammar,
PTTL key
Copy the code3.2.8.2,
This command is similar to the TTL command, but it returns the remaining lifetime of the key in milliseconds rather than seconds as the TTL command does.
3.2.8.3 Return value
- If the key does not exist, return -2. If the key exists but the remaining lifetime is not set, -1 is returned.
- Otherwise, the remaining lifetime of the key is returned in milliseconds.
- Prior to Redis 2.8, the command returned -1 when the key did not exist, or when the remaining lifetime of the key was not set.
3.2.9 RANDOMKEY instruction
3.2.9.1, grammar,
RANDOMKEY
Copy the code3.2.9.2,
Returns a key randomly (without deleting) from the current database.
3.2.9.3. Returned Value
Returns a key when the database is not empty. Returns nil when the database is empty.
3.2.10. RENAME command
3.2.10.1, grammar,
RENAME key newkey
Copy the code3.2.10.2,
Change the name of key to newKey. Returns an error if the key is the same as newKey, or if the key does not exist. When newkey already exists, the RENAME command overwrites the old value.
3.2.10.3 Return Value
An OK message is displayed when the name change succeeds, and an error is returned when the name change fails.
3.2.11 TYPE directive
3.2.11.1, grammar,
TYPE key
Copy the code3.2.11.2,
Returns the type of the value stored by key.Copy the code3.2.11.3. Return value
- None (key does not exist)
- String (string)
- List (list)
- Set
- Zset (ordered set)
- Hash table
Data types in Redis
4.1. The type is String
4.1.1 Memory Model
4.1.2 Common Operation Commands
| The command | instructions |
|---|---|
| set | Set a key/value |
| get | Get the corresponding value based on the key |
| mset | Set multiple key values at a time |
| mget | Obtain the value of multiple keys at once |
| getset | Gets the value of the original key and sets the new value |
| strlen | Obtain the length of the corresponding key store value |
| append | Append the value of the corresponding key |
| getrange | Intercept the contents of value, where -1 can represent the end (index 0 starts) |
| setex | Set the lifetime of a key in seconds |
| psetex | Set the lifetime of a key in milliseconds |
| setnx | Yes No operation is performed and no addition is performed |
| msetnx | You can set multiple keys at the same time, atomic operations, as long as one of them exists is not saved |
| decr | Perform the -1 operation on a numeric value |
| decrby | Subtract from the data provided |
| Incr | Perform a +1 operation on a numeric type |
| incrby | Add operations based on the data provided |
| Incrbyfloat | Add floating-point numbers based on the data provided |
4.2. List type
The List type in Redis is the Java equivalent of the List collection, which is characterized by the sequential and repeatable elements
4.2.1 Memory Model
4.2.2 Common operation instructions
| The command | instructions |
|---|---|
| lpush | Add a value to the header of a key list (from left) |
| lpushx | Same as lpush, but you have to make sure that this key exists |
| rpush | To add a value to the end of a key list (putting elements from the right) |
| rpushx | Same as Rpush, but you have to make sure that this key exists |
| lpop | Returns and removes the first element to the left of the list, and returns |
| rpop | Returns and removes the first element to the right of the list, and returns |
| lrange | Gets the elements in a range of subscripts (starting at 0 by default and ending at -1) |
| llen | Gets the number of elements in the list |
| lset | Sets the value of a specified index (the index must exist) |
| lindex | Gets an element at a specified index location |
| lrem | Delete duplicate elements lerm lists 3 zhangsan(delete 3 zhangsan in lists set) |
| ltrim | Retain the elements within a specific interval of the list |
| linsert | Insert new elements before and after an element |
4.3 Set type
4.3.1 Memory Model
4.3.2 Common Commands
| The command | instructions |
|---|---|
| sadd | Add elements to the collection |
| smembers | Displays all the elements in the collection, which is actually unordered |
| scard | Returns the number of elements in a collection |
| spop | Returns an element at random and removes it from the collection |
| smove | To move elements from one set to another, they must be of the same type |
| srem | Removes an element from a collection |
| sismember | Determine whether a set contains this element |
| srandmember | Random return element |
| sdiff | Get rid of the same elements in other sets of the first set |
| sinter | masked |
| sunion | Sum set |
4.4. ZSet type
It is a sortable set that cannot be repeated, also known as a sortSet.
4.4.1 Memory Model
4.4.2 Common Commands
| The command | instructions |
|---|---|
| zadd | Adds an ordered collection element |
| zcard | Returns the number of elements in the collection |
| Zrange ascending zRevRange descending | Returns an element in a range |
| zrangebyscore | Finds elements in a range by score |
| zrank | Return to top |
| zrevrank | List in reverse chronological order |
| zscore | Displays the score of an element |
| zrem | Remove an element |
| zincrby | Give points to a specific element |
4.5 Hash type
Put a map structure in value, there is a key and value, key is unordered
4.5.1 Memory Model
4.5.2 Common Commands
| The command | instructions |
|---|---|
| hset | Set a key/value pair |
| hget | Get a value corresponding to a key |
| hgetall | Get all key/value pairs |
| hdel | Example Delete a key/value pair |
| hexists | Determine whether a key exists |
| hkeys | Get all the keys |
| hvals | Get all the values |
| hmset | Set multiple keys or values |
| hmget | Get the value of multiple keys |
| hsetnx | Sets the value of a nonexistent key |
| hincrby | Add to value (implement increment) |
| hincrbyfloat | Add floating-point value to value (retain up to 17 bits) |