mysql读写分离

 

注意:进行读写分离,需要在主从复制基础上做,所以我将此前做主从复制的过程贴在下方:

读写分离简单拓扑:

wKioL1dqaXfAjTYjAABdxImfxFc434.png

注意:在实际生产环境中,应该将写操作都发往master服务器,将读操作负载调度到slave服务器。

 

使用msyql-proxy实现读写分离:

1.可通过epel源yum安装mysql-proxy

# yum -y install mysql-proxy

 

2.yum安装的mysql-proxy没有读写分离脚本rw-splitting.lua

法1:

使用官方二进制格式文件中的rw-splitting.lua脚本进行读写分离。

# tar xf mysql-proxy-0.8.5-linux-el6-x86-64bit.tar.gz

# ls /root/mysql-proxy-0.8.5-linux-el6-x86-64bit/share/doc/mysql-proxy

active-queries.lua       commit-obfuscator.msc  ro-pooling.lua          tutorial-monitor.lua     tutorial-routing.lua   xtab.lua

active-transactions.lua  COPYING                rw-splitting.lua        tutorial-packets.lua     tutorial-scramble.lua

admin-sql.lua            histogram.lua          tutorial-basic.lua      tutorial-prep-stmts.lua  tutorial-states.lua

analyze-query.lua        load-multi.lua         tutorial-constants.lua  tutorial-query-time.lua  tutorial-tokenize.lua

auditing.lua             README                 tutorial-inject.lua     tutorial-resultset.lua   tutorial-union.lua

commit-obfuscator.lua    ro-balance.lua         tutorial-keepalive.lua  tutorial-rewrite.lua     tutorial-warnings.lua

 

法2:

将下方代码保存为rw-splitting.lua。

--[[ $%BEGINLICENSE%$

 Copyright (c) 2007, 2012, Oracle and/or its affiliates. All rights reserved.

 

 This program is free software; you can redistribute it and/or

 modify it under the terms of the GNU General Public License as

 published by the Free Software Foundation; version 2 of the

 License.

 

 This program is distributed in the hope that it will be useful,

 but WITHOUT ANY WARRANTY; without even the implied warranty of

 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

 GNU General Public License for more details.

 

 You should have received a copy of the GNU General Public License

 along with this program; if not, write to the Free Software

 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA

 02110-1301  USA

 

 $%ENDLICENSE%$ --]]

 

---

-- a flexible statement based load balancer with connection pooling

--

-- * build a connection pool of min_idle_connections for each backend and maintain

--   its size

-- *

--

--

 

local commands    = require("proxy.commands")

local tokenizer   = require("proxy.tokenizer")

local lb          = require("proxy.balance")

local auto_config = require("proxy.auto-config")

 

--- config

--

-- connection pool

if not proxy.global.config.rwsplit then

proxy.global.config.rwsplit = {

min_idle_connections = 4,

max_idle_connections = 8,

 

is_debug = false

}

end

 

---

-- read/write splitting sends all non-transactional SELECTs to the slaves

--

-- is_in_transaction tracks the state of the transactions

local is_in_transaction       = false

 

-- if this was a SELECT SQL_CALC_FOUND_ROWS ... stay on the same connections

local is_in_select_calc_found_rows = false

 

---

-- get a connection to a backend

--

-- as long as we don't have enough connections in the pool, create new connections

--

function connect_server()

local is_debug = proxy.global.config.rwsplit.is_debug

-- make sure that we connect to each backend at least ones to

-- keep the connections to the servers alive

--

-- on read_query we can switch the backends again to another backend

 

if is_debug then

print()

print("[connect_server] " .. proxy.connection.client.src.name)

end

 

local rw_ndx = 0

 

-- init all backends

for i = 1, #proxy.global.backends do

local s        = proxy.global.backends[i]

local pool     = s.pool -- we don't have a username yet, try to find a connections which is idling

local cur_idle = pool.users[""].cur_idle_connections

 

pool.min_idle_connections = proxy.global.config.rwsplit.min_idle_connections

pool.max_idle_connections = proxy.global.config.rwsplit.max_idle_connections

 

if is_debug then

print("  [".. i .."].connected_clients = " .. s.connected_clients)

print("  [".. i .."].pool.cur_idle     = " .. cur_idle)

print("  [".. i .."].pool.max_idle     = " .. pool.max_idle_connections)

print("  [".. i .."].pool.min_idle     = " .. pool.min_idle_connections)

print("  [".. i .."].type = " .. s.type)

print("  [".. i .."].state = " .. s.state)

end

 

-- prefer connections to the master

if s.type == proxy.BACKEND_TYPE_RW and

   s.state ~= proxy.BACKEND_STATE_DOWN and

   cur_idle < pool.min_idle_connections then

proxy.connection.backend_ndx = i

break

elseif s.type == proxy.BACKEND_TYPE_RO and

       s.state ~= proxy.BACKEND_STATE_DOWN and

       cur_idle < pool.min_idle_connections then

proxy.connection.backend_ndx = i

break

elseif s.type == proxy.BACKEND_TYPE_RW and

       s.state ~= proxy.BACKEND_STATE_DOWN and

       rw_ndx == 0 then

rw_ndx = i

end

end

 

if proxy.connection.backend_ndx == 0 then

if is_debug then

print("  [" .. rw_ndx .. "] taking master as default")

end

proxy.connection.backend_ndx = rw_ndx

end

 

-- pick a random backend

--

-- we someone have to skip DOWN backends

 

-- ok, did we got a backend ?

 

if proxy.connection.server then

if is_debug then

print("  using pooled connection from: " .. proxy.connection.backend_ndx)

end

 

-- stay with it

return proxy.PROXY_IGNORE_RESULT

end

 

if is_debug then

print("  [" .. proxy.connection.backend_ndx .. "] idle-conns below min-idle")

end

 

-- open a new connection

end

 

---

-- put the successfully authed connection into the connection pool

--

-- @param auth the context information for the auth

--

-- auth.packet is the packet

function read_auth_result( auth )

if is_debug then

print("[read_auth_result] " .. proxy.connection.client.src.name)

end

if auth.packet:byte() == proxy.MYSQLD_PACKET_OK then

-- auth was fine, disconnect from the server

proxy.connection.backend_ndx = 0

elseif auth.packet:byte() == proxy.MYSQLD_PACKET_EOF then

-- we received either a

--

-- * MYSQLD_PACKET_ERR and the auth failed or

-- * MYSQLD_PACKET_EOF which means a OLD PASSWORD (4.0) was sent

print("(read_auth_result) ... not ok yet");

elseif auth.packet:byte() == proxy.MYSQLD_PACKET_ERR then

-- auth failed

end

end

 

 

---

-- read/write splitting

function read_query( packet )

local is_debug = proxy.global.config.rwsplit.is_debug

local cmd      = commands.parse(packet)

local c        = proxy.connection.client

 

local r = auto_config.handle(cmd)

if r then return r end

 

local tokens

local norm_query

 

-- looks like we have to forward this statement to a backend

if is_debug then

print("[read_query] " .. proxy.connection.client.src.name)

print("  current backend   = " .. proxy.connection.backend_ndx)

print("  client default db = " .. c.default_db)

print("  client username   = " .. c.username)

if cmd.type == proxy.COM_QUERY then

print("  query             = "        .. cmd.query)

end

end

 

if cmd.type == proxy.COM_QUIT then

-- don't send COM_QUIT to the backend. We manage the connection

-- in all aspects.

proxy.response = {

type = proxy.MYSQLD_PACKET_OK,

}

 

if is_debug then

print("  (QUIT) current backend   = " .. proxy.connection.backend_ndx)

end

 

return proxy.PROXY_SEND_RESULT

end

 

-- COM_BINLOG_DUMP packet can't be balanced

--

-- so we must send it always to the master

if cmd.type == proxy.COM_BINLOG_DUMP then

-- if we don't have a backend selected, let's pick the master

--

if proxy.connection.backend_ndx == 0 then

proxy.connection.backend_ndx = lb.idle_failsafe_rw()

end

 

return

end

 

proxy.queries:append(1, packet, { resultset_is_needed = true })

 

-- read/write splitting

--

-- send all non-transactional SELECTs to a slave

if not is_in_transaction and

   cmd.type == proxy.COM_QUERY then

tokens     = tokens or assert(tokenizer.tokenize(cmd.query))

 

local stmt = tokenizer.first_stmt_token(tokens)

 

if stmt.token_name == "TK_SQL_SELECT" then

is_in_select_calc_found_rows = false

local is_insert_id = false

 

for i = 1, #tokens do

local token = tokens[i]

-- SQL_CALC_FOUND_ROWS + FOUND_ROWS() have to be executed

-- on the same connection

-- print("token: " .. token.token_name)

-- print("  val: " .. token.text)

 

if not is_in_select_calc_found_rows and token.token_name == "TK_SQL_SQL_CALC_FOUND_ROWS" then

is_in_select_calc_found_rows = true

elseif not is_insert_id and token.token_name == "TK_LITERAL" then

local utext = token.text:upper()

 

if utext == "LAST_INSERT_ID" or

   utext == "@@INSERT_ID" then

is_insert_id = true

end

end

 

-- we found the two special token, we can't find more

if is_insert_id and is_in_select_calc_found_rows then

break

end

end

 

-- if we ask for the last-insert-id we have to ask it on the original

-- connection

if not is_insert_id then

local backend_ndx = lb.idle_ro()

 

if backend_ndx > 0 then

proxy.connection.backend_ndx = backend_ndx

end

else

print("   found a SELECT LAST_INSERT_ID(), staying on the same backend")

end

end

end

 

-- no backend selected yet, pick a master

if proxy.connection.backend_ndx == 0 then

-- we don't have a backend right now

--

-- let's pick a master as a good default

--

proxy.connection.backend_ndx = lb.idle_failsafe_rw()

end

 

-- by now we should have a backend

--

-- in case the master is down, we have to close the client connections

-- otherwise we can go on

if proxy.connection.backend_ndx == 0 then

return proxy.PROXY_SEND_QUERY

end

 

local s = proxy.connection.server

 

-- if client and server db don't match, adjust the server-side

--

-- skip it if we send a INIT_DB anyway

if cmd.type ~= proxy.COM_INIT_DB and

   c.default_db and c.default_db ~= s.default_db then

print("    server default db: " .. s.default_db)

print("    client default db: " .. c.default_db)

print("    syncronizing")

proxy.queries:prepend(2, string.char(proxy.COM_INIT_DB) .. c.default_db, { resultset_is_needed = true })

end

 

-- send to master

if is_debug then

if proxy.connection.backend_ndx > 0 then

local b = proxy.global.backends[proxy.connection.backend_ndx]

print("  sending to backend : " .. b.dst.name);

print("    is_slave         : " .. tostring(b.type == proxy.BACKEND_TYPE_RO));

print("    server default db: " .. s.default_db)

print("    server username  : " .. s.username)

end

print("    in_trans        : " .. tostring(is_in_transaction))

print("    in_calc_found   : " .. tostring(is_in_select_calc_found_rows))

print("    COM_QUERY       : " .. tostring(cmd.type == proxy.COM_QUERY))

end

 

return proxy.PROXY_SEND_QUERY

end

 

---

-- as long as we are in a transaction keep the connection

-- otherwise release it so another client can use it

function read_query_result( inj )

local is_debug = proxy.global.config.rwsplit.is_debug

local res      = assert(inj.resultset)

          local flags    = res.flags

 

if inj.id ~= 1 then

-- ignore the result of the USE <default_db>

-- the DB might not exist on the backend, what do do ?

--

if inj.id == 2 then

-- the injected INIT_DB failed as the slave doesn't have this DB

-- or doesn't have permissions to read from it

if res.query_status == proxy.MYSQLD_PACKET_ERR then

proxy.queries:reset()

 

proxy.response = {

type = proxy.MYSQLD_PACKET_ERR,

errmsg = "can't change DB ".. proxy.connection.client.default_db ..

" to on slave " .. proxy.global.backends[proxy.connection.backend_ndx].dst.name

}

 

return proxy.PROXY_SEND_RESULT

end

end

return proxy.PROXY_IGNORE_RESULT

end

 

is_in_transaction = flags.in_trans

local have_last_insert_id = (res.insert_id and (res.insert_id > 0))

 

if not is_in_transaction and

   not is_in_select_calc_found_rows and

   not have_last_insert_id then

-- release the backend

proxy.connection.backend_ndx = 0

elseif is_debug then

print("(read_query_result) staying on the same backend")

print("    in_trans        : " .. tostring(is_in_transaction))

print("    in_calc_found   : " .. tostring(is_in_select_calc_found_rows))

print("    have_insert_id  : " .. tostring(have_last_insert_id))

end

end

 

---

-- close the connections if we have enough connections in the pool

--

-- @return nil - close connection

--         IGNORE_RESULT - store connection in the pool

function disconnect_client()

local is_debug = proxy.global.config.rwsplit.is_debug

if is_debug then

print("[disconnect_client] " .. proxy.connection.client.src.name)

end

 

-- make sure we are disconnection from the connection

-- to move the connection into the pool

proxy.connection.backend_ndx = 0

end

3.修改配置文件/etc/mysql-proxy.cnf

# vim /etc/mysql-proxy.cnf

[mysql-proxy]                                                           #全局配置段

daemon = true                                                           #以守护进程方式运行

pid-file = /var/run/mysql-proxy.pid                                     #进程PID文件路径

log-file = /var/log/mysql-proxy.log                                     #日志路径

log-level = debug                                                       #日志级别

max-open-files = 1024

plugins = admin,proxy

user = mysql-proxy

#

#Proxy Configuration                                                    #代理配置段

proxy-address = 192.168.43.111:3306                                     #代理地址,即为本机地址

proxy-backend-addresses = 192.168.43.113:3306                           #可读写后端主机

proxy-read-only-backend-addresses = 192.168.43.110:3306                 #只读后端主机

proxy-lua-script = /usr/lib64/mysql-proxy/lua/rw-splitting.lua          #脚本,指向读写分离脚本(rw-splitting.lua)实现读写分离

#proxy-skip-profiling = true                                            #禁用profile

#

# Admin Configuration                                                   #管理配置段

admin-address = 192.168.43.111:4041                                     #管理地址和端口

admin-lua-script = /usr/lib64/mysql-proxy/lua/admin.lua                 #使用的管理脚本为admin.lua

admin-username = admin                                                  #管理用户

admin-password = admin                                                  #管理密码

 

4.启动服务,测试

# mysql -uadmin -padmin -P4041 -h192.168.43.111

Welcome to the MySQL monitor.  Commands end with ; or \g.

Your MySQL connection id is 1

Server version: 5.0.99-agent-admin

 

Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.

 

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

 

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

 

查看后端主机状态:

mysql> select * from backends;

+-------------+---------------------+---------+------+------+-------------------+

| backend_ndx | address             | state   | type | uuid | connected_clients |

+-------------+---------------------+---------+------+------+-------------------+

|           1 | 192.168.43.113:3306 | up      | rw   | NULL |                 0 |

|           2 | 192.168.43.110:3306 | unknown | ro   | NULL |                 0 |

+-------------+---------------------+---------+------+------+-------------------+

#此时还没有读请求发送到只读后端,所以为uknown,执行几次下方的读请求语句再查看;

# mysql -uadmin -h192.168.43.111 -padmin -e 'select * from mysql.user;'

 

再次查看后端主机状态:

mysql> select * from backends;

+-------------+---------------------+-------+------+------+-------------------+

| backend_ndx | address             | state | type | uuid | connected_clients |

+-------------+---------------------+-------+------+------+-------------------+

|           1 | 192.168.43.113:3306 | up    | rw   | NULL |                 0 |

|           2 | 192.168.43.110:3306 | up    | ro   | NULL |                 0 |

+-------------+---------------------+-------+------+------+-------------------+

#可以看到,已经up起来;并且从type可以看出来,一个为读写,一个为只读。

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