Shulou(Shulou.com)06/01 Report--

1: Introduction to redis

Redis is similar to Memcached and is also a k-v data store.

Redis official website redis.io, the latest stable version 4.0.1

Support for more value types, hash, lists, sets, and sorted sets in addition to and string

Redis uses two file formats: full data (RDB) and incremental request (aof). The full data format is to write the data in memory to disk so that the file can be loaded next time. Increment request file is to serialize the data in memory into operation request, which is used to read the file to replay the data, which is similar to mysql binlog.

Redis storage is divided into memory storage, disk storage and log file three parts

2: Redis installation

Download the latest stable version

cd /usr/local/src/wget http://download.redis.io/releases/redis-4.0.1.tar.gzcd redis-4.0.1make && make installcp redis.conf /etc/redis.confvim /etc/redis.conf //modify the following configuration daemonize yeslogfile "/var/log/redis.log" dir /data/redis_data/appendonly yesmkdir /data/redis_datasysctl vm.overcommit_memory=1echo never > /sys/kernel/mm/transparent_hepage/enabledredis-server /etc/redis.conf

3: redis persistence

Redis provides two persistence methods, namely RDB (Redis DataBase) and AOF (Append Only File).

RDB, in short, is to generate snapshots of data stored in redis at different points in time and store them on media such as disks.

AOF, on the other hand, changes an angle to achieve persistence, that is, records all the write instructions that redis has executed. When redis restarts next time, as long as these write instructions are repeated from front to back, data recovery can be achieved.

In fact, RDB and AOF can also be used at the same time. In this case, if redis restarted, AOF will be preferred for data recovery, because AOF has higher data recovery integrity.

If you don't have data persistence requirements, you can turn off RDB and AOF altogether, and redis will become a pure memory database, just like memcache.

Redis Persistence Related Parameters

save 900 1 #means that persistence is triggered every 15 minutes with at least one key change

save 300 10 #means that persistence is triggered every 5 minutes and at least 10 key changes

save 60 10000 #means that at least 10000 key changes every 60 seconds trigger a persistent

save "" #This disables rdb persistence

appendonly yes #If yes, turn on aof persistence

appendfilename "appendonly.aof" #Specify aof file name

appendfsync everysec #Specifies the mode of fsync() invocation, there are three no(no invocation of fsync),always(invocation of fsync every time a write occurs),everysec(invocation of fsync every second). The first is the fastest, the second is the most secure, but the performance will be worse, and the third is this scheme, which is the default.

4: redis data type

Redis data type-string

string is the simplest type, the same type as Memcached, a key corresponds to a value, its supported operations are similar to Memcached operations, and its functions are richer. Set objects that can be stored in binary.

Examples:

#redis-cli127.0.0.1:6379> set mykey "aminglinux.com"OK127.0.0.1:6379> get mykey"aminglinux.com"127.0.0.1:6379> mset key1 1 key2 a key3 c127.0.0.1:6379> mget key1 key2 key31) "1"2) "a"3) "c"

Redis data type-list

A list is a linked list structure whose main function is to push, pop, get all the values of a range, and so on. Key is understood as the name of the linked list in the operation.

Using the list structure, we can easily implement features such as the latest news ranking (such as Sina Weibo's TimeLine). Another application of list is message queue. You can use the push operation of list to store tasks in list, and then the worker thread can use pop operation to take tasks out for execution.

Examples:

#redis-cli 127.0.0.1:6379> LPUSH list1 "aminglinux"127.0.0.1:6379> LPUSH list1 "1 2 3"127.0.0.1:6379> LPUSH list1 "aaa bbb"127.0.0.1:6379> LRANGE list1 0 -11) "aaa bbb"2) "1 2 3"3) "aminglinux"127.0.0.1:6379> LPOP list1

Redis data type-set

Set is a set, similar to the concept of set in mathematics. There are operations on the set, such as adding and deleting elements, and finding the intersection and difference of multiple sets. Key is understood to be the name of the collection. For example, in a microblogging application, all followers of a user can be stored in a collection, and all fans can be stored in a collection. Because Redis is very user-friendly for the collection to provide intersection, union, difference set and other operations, then you can very convenient to implement such as common attention, common preferences, second degree friends and other functions, for all the above collection operations, you can also use different commands to choose whether to return the results to the client or save the collection to a new collection.

set example

127.0.0.1: 6379> SADD set1 a127.0.0.1:6379> SADD set1 b127.0.0.1:6379> SADD set1 c127.0.0.1:6379> SADD set1 d127.0.0.1:6379> SMEBERS set11) "d"2) "b"3) "a"4) "c" 127.0.0.1: 6379> SREM set1 c//Delete element 127.0.0.1: 6379> SADD set2 a 2 b127.0.0.1:6379> SINTER set1 set2 //intersection 127.0.1: 6379> SUNION set1 set 2//union 127.0.0.1: 6379> SDIFF set1 set2//difference set

Redis data type-sort set

Sorted set is an ordered set, which has one more weight parameter score than set, so that the elements in the set can be arranged in order according to score, such as a Sorted Sets that stores the scores of the whole class. The set value can be the student number of the classmate, and the score can be the test score. In this way, when the data is inserted into the set, it has been sorted naturally.

127.0.0.1:6379> ZADD set3 12 abc127.0.0.1:6379> ZADD set3 2 "cde 123"127.0.0.1:6379> ZADD set3 24 "123-aaa"127.0.0.1:6379> ZADD set3 4 "a123a"127.0.0.1:6379> ZRANGE set3 0 -11) "cde 123"2) "a123a"3) "abc"4) "123-aaa"

reverse order

127.0.0.1:6379> ZREVRANGE set3 0 -1

1) "123-aaa"

2) "abc"

3) "a123a"

4) "cde 123"

Redis data type-hash

In Memcached, we often package some structured information into hashmaps, which are serialized on the client side and stored as a string of values (usually in JSON format), such as the user's nickname, age, gender, points, etc.

example

127.0.0.1:6379> hset hash2 name aming127.0.0.1:6379> hget hash2 name"aming"127.0.0.1:6379> hset hash2 age 30127.0.0.1:6379> hget hash2 age"30"127.0.0.1:6379> hgetall hash21) "name"2) "aming"3) "age"4) "30"

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