redis

由 datahunter 在五, 16/11/2018 - 12:27 發表

最後更新: 2022-06-29

介紹

Redis is an open source (BSD licensed), in-memory data structure store, used as a database, cache and message broker.

Redis keys are binary safe.

Try to stick with a schema. The colon sign ":" is a convention when naming keys.

For example: "object-type:id:field1.field2" is a good idea

It supports data structures such as

strings(binary safe, max: 512 M),
hashes,
lists,
sets,
sorted sets with range queries,
bitmaps,
hyperloglogs,
geospatial indexes with radius queries and streams.

Redis has built-in replication, Lua scripting, LRU eviction, transactions and different levels of on-disk persistence,

and provides high availability via Redis Sentinel and automatic partitioning with Redis Cluster.

Info

port: 127.0.0.1:6379

user: redis

Check version

redis-server -v

redis-cli -v

127.0.0.1:6379> info server

# Server
redis_version:6.2.7
redis_git_sha1:00000000
redis_git_dirty:0
redis_build_id:56aeeede275be948
redis_mode:standalone
os:Linux 4.18.0-372.26.1.el8_6.x86_64 x86_64
...

Install

# C7 - EPEL Ver: 3.2

yum install redis

# Redis cluster management utility

# providing cluster creation, node addition and removal, status checks, resharding, rebalancing, and other operations.

redis-trib

Compile from source

yum install jemalloc-devel lua-devel hiredis-devel

tar -xzf redis-*.tar.gz

cd redis-*

make

Troubleshoot

cc: error: ../deps/hiredis/libhiredis.a: No such file or directory
cc: error: ../deps/jemalloc/lib/libjemalloc.a: No such file or directory

# solve by run

make distclean

cp -f redis-benchmark /usr/bin/redis-benchmark

cp -f redis-cli /usr/bin/redis-cli

cp -f redis-sentinel /usr/bin/redis-sentinel

cp -f redis-server /usr/bin/redis-server

cp -f redis-check-aof /usr/bin/redis-check-aof

cp -f redis-check-rdb /usr/bin/redis-check-rdb

Test(CLI)

# Start Server

redis-server

# Client

redis-cli ping

redis> set foo bar

OK

redis> get foo

"bar"

Configure

maxmemory

# When the memory limit is reached Redis will try to remove keys
# according to the eviction policy selected

maxmemory 128mb

# Checking

grep ^maxmemory /etc/redis.conf

redis-cli
config get maxmemory

maxmemory-policy

maxmemory-policy allkeys-lfu

LRU means Least Recently Use
LFU means Least Frequently Used
volatile = the keys with an expire set
allkeys = any key

Opts

allkeys-lru: Redis will remove the least recently used keys in order to make space for new keys.
allkeys-lfu: Evict any key using approximated LFU.

volatile-lru: Redis will remove the least recently used keys among keys with an expire set in order to make space for new keys.
volatile-lfu: Evict using approximated LFU among the keys with an expire set.
volatile-ttl: Remove the key with the nearest expire time (minor TTL)

allkeys-random: Redis will randomly select keys to remove in order to make space for new keys.
volatile-random: Remove a random key among the ones with an expire set.

noeviction: Redis will return an error when the maximum memory limit is reached and a new key needs to be added.

maxmemory-samples

# For default Redis will check five keys and pick the one that was used less recently

maxmemory-samples 5

redis-cli

redis-cli [ options ] [cmd [arg [arg ...]]]

OPTIONS

Connect

-h hostname Server hostname (default: 127.0.0.1).
-p port Server port (default: 6379).
-s socket Server socket (overrides hostname and port).
-a password Password to use when connecting to the server.
建議用 environment variable: REDISCLI_AUTH

Search

# KEYS

redis-cli KEYS 'PHPREDIS_SESSION:*'

# SCAN

SCAN cursor [MATCH pattern] [COUNT count]

--scan List all keys using the SCAN command.
--pattern specify a SCAN pattern

Output format

--csv Output in CSV format.

--raw Use raw formatting for replies. force raw output even on the terminal(tty)

當是 terminal 時, output: "(integer) 7"

Repeat

-r repeat # Execute specified command N times.

-i <delay> # Unit: second. 0.1 = 100 ms

Run

-x # Read last argument from STDIN.

--eval file Send an EVAL command using the Lua script at file.

Example

# 將 mycounter +1, 另有 "DECR"

redis-cli INCR mycounter

# raw output to terminal(tty)

redis-cli --raw INCR mycounter

# Redis GET all Keys

KEYS *PHPREDIS_SESSION*

# 在 bash shell 時, "*" 要加 "\"

redis-cli KEYS PHPREDIS_SESSION\*

PHPREDIS_SESSION:UUID
...

# 將 mycounter +5

redis-cli -r 5 INCR mycounter

# set value by file

redis-cli -x SET mycounter < mycounter.txt

cat commands.txt | redis-cli

commands.txt

SET arg_example "This is a single argument"
STRLEN arg_example

redis-cli LPUSH mylist a b c d

(integer) 4

redis-cli --csv LRANGE mylist 0 -1

"d","c","b","a"

redis-cli --scan --pattern '*:12345*'

List

LPUSH mylist a # inserts a new element on the head

LPUSH mylist b #

RPUSH mylist c # inserts a new element on the tail

LRANGE key start stop # list of elements in the specified range

0 being the first element of the list

-1 is the last element of the list

Out-of-range indexes

Out of range indexes will not produce an error. If start is larger than the end of the list, an empty list is returned.

If stop is larger than the actual end of the list, Redis will treat it like the last element of the list.

Monitoring

Status

--stat Print rolling stats about server: mem, clients, ... # printed every second

------- data ------ --------------------- load -------------------- - child -
keys       mem      clients blocked requests            connections
124        5.31M    3       0       439303 (+0)         219659
124        5.31M    3       0       439304 (+1)         219659

connections: 應負了多小個 connection

requests: 上一秒有多少個 request

Monitoring commands executed in Redis

redis-cli MONITOR # 它是不當 request 的

OK
1656476570.281821 [0 10.1.2.6:50968] "info"
...

Latency

# The stats are provided in milliseconds.

# Using this option the CLI runs a loop where the PING command is sent to the Redis instance

redis-cli --latency

min: 0, max: 4, avg: 0.25 (1113 samples)^C

By default: every 15 seconds

redis-cli --latency-history

Remote backups of RDB files

redis-cli --rdb /tmp/dump.rdb

System Settings

/etc/systemd/system/redis.service.d/limit.conf

[Service]
LimitNOFILE=10240

/etc/logrotate.d/redis

/var/log/redis/*.log {
    weekly
    rotate 10
    copytruncate
    delaycompress
    compress
    notifempty
    missingok
}

/usr/lib/systemd/system/redis.service

[Unit]
Description=Redis persistent key-value database
After=network.target
After=network-online.target
Wants=network-online.target

[Service]
ExecStart=/usr/bin/redis-server /etc/redis.conf --supervised systemd
ExecStop=/usr/libexec/redis-shutdown
Type=notify
User=redis
Group=redis
RuntimeDirectory=redis
RuntimeDirectoryMode=0755

[Install]
WantedBy=multi-user.target

PHP Session

php 建立 session

... "get" "PHPREDIS_SESSION:UUID"
... "setex" "PHPREDIS_SESSION:UUID" "28800"

之後每1 Click 都會 setx 一次.

SETX

# Set key to hold the string value and set key to timeout after a given number of seconds.

(相當於 SET EXPIRE 一句完成)

SET mykey value
EXPIRE mykey seconds

setex key seconds value

TTL

# Returns the remaining time to live of a key that has a timeout.

TTL KEY_NAME

Expire

Set a timeout on key

Expire KEY_NAME TIME_IN_SECONDS

Return Value

1, if the timeout is set for the key.
0, if the key does not exist or timeout could not set.

PHP

Php Package

yum install php-pecl-redis # Centos 7

Check Redis Script

test-redis.php

<?php
   $redis = new Redis();
   $redis->connect('127.0.0.1', 6379);
   echo "Server is running: " . $redis->ping();
?>

Session in Redis

/etc/httpd/conf.d/php.conf # Centos 7

# 原本 (file)

php_value session.save_handler "files"
php_value session.save_path    "/var/lib/php/mod_php/session"

# 使用 Redis

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