Redis 3.2文檔-1.比較3.0

一、Redis3.0與3.2檔案對比

1. clone redis

git clone https://github.com/antirez/redis.git      

2. checkout分支

cd redis
git checkout 3.0
git checkout 3.2      

3. 比較

(1) 比較3.0和3.2檔案變化數

> git rev-list 3.0..3.2 --count
1708      

(2) 比較3.0和3.2檔案變化統計

> git diff 3.0..3.2 --shortstat
比較3.0和3.2檔案變化數      

二、Redis3.0與3.2預設配置檔案變化

1.配置變化

Redis3.2添加了兩個配置：

• protected-mode yes
• supervised no

Redis3.2修改了個配置：

有關list的優化，由配置一改為配置二，雖然還沒詳細了解，應該是list的底層資料結構做了一些新的變化或者優化。

配置一：

list-max-ziplist-entries 512
list-max-ziplist-value 64      

配置二： 

list-max-ziplist-size -2
list-compress-depth 0      

配置三： 

bind 127.0.0.1      

bind在Redis3.2.0中預設改為127.0.0.1 

2.新配置說明

• (1).protected-mode(預設是yes)

# Protected mode is a layer of security protection, in order to avoid that
# Redis instances left open on the internet are accessed and exploited.
#
# When protected mode is on and if:
#
# 1) The server is not binding explicitly to a set of addresses using the
#    "bind" directive.
# 2) No password is configured.
#
# The server only accepts connections from clients connecting from the
# IPv4 and IPv6 loopback addresses 127.0.0.1 and ::1, and from Unix domain
# sockets.
#
# By default protected mode is enabled. You should disable it only if
# you are sure you want clients from other hosts to connect to Redis
# even if no authentication is configured, nor a specific set of interfaces
# are explicitly listed using the "bind" directive.      

說明

• 用一段代碼就可以說明什麼是protected-mode

  if (protected-mode && !requirepass && !bind) {
  	Allow only 127.0.0.1,::1 or socket connections
      Deny (with the long message ever!) others 
  }      

• 其實設定成預設是為了保護對redis不了解的人，提供安全性，但是對于對于不需要bind和requirepass的使用者（例如内網），需要将protected-mode設定為no

• (2).supervised(預設是no)

# If you run Redis from upstart or systemd, Redis can interact with your
# supervision tree. Options:
#   supervised no      - no supervision interaction
#   supervised upstart - signal upstart by putting Redis into SIGSTOP mode
#   supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET
#   supervised auto    - detect upstart or systemd method based on
#                        UPSTART_JOB or NOTIFY_SOCKET environment variables
# Note: these supervision methods only signal "process is ready."
#       They do not enable continuous liveness pings back to your supervisor.      

可以通過upstart和systemd管理Redis守護程序，這個參數是和具體的作業系統相關的。

• (3).bind (Redis3.2.0中bind預設是127.0.0.1)

# By default, if no "bind" configuration directive is specified, Redis listens
# for connections from all the network interfaces available on the server.
# It is possible to listen to just one or multiple selected interfaces using
# the "bind" configuration directive, followed by one or more IP addresses.
#
# Examples:
#
# bind 192.168.1.100 10.0.0.1
# bind 127.0.0.1 ::1
#
# ~~~ WARNING ~~~ If the computer running Redis is directly exposed to the
# internet, binding to all the interfaces is dangerous and will expose the
# instance to everybody on the internet. So by default we uncomment the
# following bind directive, that will force Redis to listen only into
# the IPv4 lookback interface address (this means Redis will be able to
# accept connections only from clients running into the same computer it
# is running).
#
# IF YOU ARE SURE YOU WANT YOUR INSTANCE TO LISTEN TO ALL THE INTERFACES
# JUST COMMENT THE FOLLOWING LINE.
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
bind 127.0.0.1      

bind在Redis3.2.0之前預設是0.0.0.0或者說””，為了保證不太了解Redis安全性的人，在Redis3.2.0中bind預設是127.0.0.1,也就是隻有本機回環位址可以通路。如果需要配置sentinel、cluster或者需要機器機器可以通路該Redis執行個體請修改為0.0.0.0或者指定的内網IP.

• (4).list-max-ziplist-size(預設-2)

  # Lists are also encoded in a special way to save a lot of space.
  # The number of entries allowed per internal list node can be specified
  # as a fixed maximum size or a maximum number of elements.
  # For a fixed maximum size, use -5 through -1, meaning:
  # -5: max size: 64 Kb  <-- not recommended for normal workloads
  # -4: max size: 32 Kb  <-- not recommended
  # -3: max size: 16 Kb  <-- probably not recommended
  # -2: max size: 8 Kb   <-- good
  # -1: max size: 4 Kb   <-- good
  # Positive numbers mean store up to _exactly_ that number of elements
  # per list node.
  # The highest performing option is usually -2 (8 Kb size) or -1 (4 Kb size),
  # but if your use case is unique, adjust the settings as necessary.      

• (5).list-compress-depth(預設是0)

  # Lists may also be compressed.
  # Compress depth is the number of quicklist ziplist nodes from *each* side of
  # the list to *exclude* from compression.  The head and tail of the list
  # are always uncompressed for fast push/pop operations.  Settings are:
  # 0: disable all list compression
  # 1: depth 1 means "don't start compressing until after 1 node into the list,
  #    going from either the head or tail"
  #    So: [head]->node->node->...->node->[tail]
  #    [head], [tail] will always be uncompressed; inner nodes will compress.
  # 2: [head]->[next]->node->node->...->node->[prev]->[tail]
  #    2 here means: don't compress head or head->next or tail->prev or tail,
  #    but compress all nodes between them.
  # 3: [head]->[next]->[next]->node->node->...->node->[prev]->[prev]->[tail]
  # etc.      

Redis3.2.0引入了新的quicklist的資料結構做了list的底層存儲方案。廢棄了原來的兩個配置參數，list-max-ziplist-entries和list-max-ziplist-value

127.0.0.1:6388> config get list-max-ziplist-size
1) "list-max-ziplist-size"
2) "-2"
127.0.0.1:6388> config get list-compress-depth
1) "list-compress-depth"
2) "0"
127.0.0.1:6388> lpush user_list u1 u2 u5 u7 u99 u10 u3
(integer) 7
127.0.0.1:6388> object encoding user_list
"quicklist"      

在Redis3.2.0中設定原來的參數已經不生效了，應該是無法使用了。

127.0.0.1:6388> config set list-max-ziplist-entries 512
(error) ERR Unsupported CONFIG parameter: list-max-ziplist-entries
127.0.0.1:6388> config set list-max-ziplist-value 64
(error) ERR Unsupported CONFIG parameter: list-max-ziplist-value      

有關quicklist的詳細使用還需要查詢文檔和源碼來研究

三、 Redis3.0與3.2關于Cluster的一些變化(來自 3.2-release-notes )

原文：

寫道

Redis Cluster changes:

All the Redis Cluster changes in 3.2 were backported to 3.0, so there is

technically nothing new for now in this release. The most important things

are:

* Cluster rebalancing.

* A pipelined MIGRATE command which is 10x faster and makes resharding

and rebalancing faster.

* Improved replicas migration.

* As a side effect of quicklists encoding (see above items), moving big

lists between nodes is now a lot faster.

Redis3.2.0的cluster完全相容Redis3.0,也就是說可以混合部署組成叢集，在Redis Cluster上Redis3.2.0沒有做什麼新的技術，但是也有一些比較重要的事情： 

• Redis Cluster均衡（應該是指redis-trib.rb中實作類将slot進行負載均衡的功能）
• 提供了一個基于流水線的migrate指令，用于水準遷移資料，速度是原來的10倍多。
• 提升了從幾點遷移的功能。
• 在quicklist這種新的資料結構的幫助下，在節點之間遷移大的big list快了很多.

注意：上述特性均在Redis3.0.7有展現，如果對于Redis3.2.0不太放心的話，可以使用Redis3.0.7。

四、 Redis3.0與3.2關于Sentinel的一些變化(來自

Redis Sentinel changes:

* [NEW] Sentinel connection sharing. Makes Sentinels able to scale to

monitor many masters. (Salvatore Sanfilippo)

* [NEW] New SENTINEL INFO-CACHE command. (Matt Stancliff)

* More things backported to Redis 3.0 in the past, so no longer news of 3.2.

 Sentinel connection sharing

不太了解，看着像是添加新的sentinel節點後，可以共享其他sentinel節點的master，對于sentinel監控多個master比較有用，這樣擴充sentinel節點時候比較友善配置，有關這個後面會繼續試驗。 

• 提供info-cache指令