MySQL 5.6引入的GTID(Global Transaction IDs)使得其複製功能的配置、監控及管理變得更加易於實現，且更加健壯。
要在MySQL 5.6中使用複製功能，其服務配置段[mysqld]中於少應該定義如下選項：
binlog-format：二進制日誌的格式，有row、statement和mixed幾種類型；
需要注意的是：當設置隔離級別爲READ-COMMITED必須設置二進制日誌格式爲ROW，現在MySQL官方認爲STATEMENT這個已經不再適合繼續使用；但mixed類型在默認的事務隔離級別下，可能會導致主從數據不一致；
log-slave-updates、gtid-mode、enforce-gtid-consistency、report-port和report-host：用於啓動GTID及滿足附屬的其它需求；
master-info-repository和relay-log-info-repository：啓用此兩項，可用於實現在崩潰時保證二進制及從服務器安全的功能；
sync-master-info：啓用之可確保無信息丟失；
slave-paralles-workers：設定從服務器的SQL線程數；0表示關閉多線程複製功能；
binlog-checksum、master-verify-checksum和slave-sql-verify-checksum：啓用複製有關的所有校驗功能；
binlog-rows-query-log-events：啓用之可用於在二進制日誌記錄事件相關的信息，可降低故障排除的複雜度；
log-bin：啓用二進制日誌，這是保證複製功能的基本前提；
server-id：同一個複製拓撲中的所有服務器的id號必須惟一；
report-host：
The host name or IP address of the slave to be reported to the master during slave registration. This value appears in the output of SHOW SLAVE HOSTS on the master server.
report-port:
The TCP/IP port number for connecting to the slave, to be reported to the master during slave registration.
master-info-repository:
The setting of this variable determines whether the slave logs master status and connection information to a FILE (master.info), or to a TABLE (mysql.slave_master_info)
relay-log-info-repository：
This option causes the server to log its relay log info to a file or a table.
log_slave_updates：
Whether updates received by a slave server from a master server should be logged to the slave's own binary log. Binary logging must be enabled on the slave for this variable to have any effect.
enforce_gtid_consistency：
一、簡單主從模式配置步驟
1、配置主從節點的服務配置文件
1.1、配置master節點：
[mysqld]
binlog-format=ROW
log-bin=master-bin
log-slave-updates=true
gtid-mode=on
enforce-gtid-consistency=true
master-info-repository=TABLE
relay-log-info-repository=TABLE
sync-master-info=1
slave-parallel-workers=2
binlog-checksum=CRC32
master-verify-checksum=1
slave-sql-verify-checksum=1
binlog-rows-query-log_events=1
server-id=1
report-port=3306
port=3306
datadir=/mydata/data
socket=/tmp/mysql.sock
report-host=master.magedu.com
1.2、配置slave節點：
[mysqld]
binlog-format=ROW
log-slave-updates=true
gtid-mode=on
enforce-gtid-consistency=true
master-info-repository=TABLE
relay-log-info-repository=TABLE
sync-master-info=1
slave-parallel-workers=2
binlog-checksum=CRC32
master-verify-checksum=1
slave-sql-verify-checksum=1
binlog-rows-query-log_events=1
server-id=11
report-port=3306
port=3306
log-bin=mysql-bin.log
datadir=/mydata/data
socket=/tmp/mysql.sock
report-host=slave.magedu.com
2、創建複製用戶
mysql> GRANT REPLICATION SLAVE ON *.* TO [email protected] IDENTIFIED BY 'replpass';
說明：172.16.100.7是從節點服務器；如果想一次性授權更多的節點，可以自行根據需要修改；
3、爲備節點提供初始數據集
鎖定主表，備份主節點上的數據，將其還原至從節點；如果沒有啓用GTID，在備份時需要在master上使用show master status命令查看二進制日誌文件名稱及事件位置，以便後面啓動slave節點時使用。
4、啓動從節點的複製線程
如果啓用了GTID功能，則使用如下命令：
mysql> CHANGE MASTER TO MASTER_HOST='master.magedu.com', MASTER_USER='repluser', MASTER_PASSWORD='replpass', MASTER_AUTO_POSITION=1;
沒啓用GTID，需要使用如下命令：
slave> CHANGE MASTER TO MASTER_HOST='172.16.100.6',
-> MASTER_USER='repluser',
-> MASTER_PASSWORD='replpass',
-> MASTER_LOG_FILE='master-bin.000003',
-> MASTER_LOG_POS=1174;
二、半同步複製
1、分別在主從節點上安裝相關的插件
master> INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so';
slave> INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so';
2、啓用半同步複製
在master上的配置文件中，添加
rpl_semi_sync_master_enabled=ON
在至少一個slave節點的配置文件中添加
rpl_semi_sync_slave_enabled=ON
而後重新啓動mysql服務即可生效。
或者，也可以mysql服務上動態啓動其相關功能：
master> SET GLOBAL rpl_semi_sync_master_enabled = ON;
slave> SET GLOBAL rpl_semi_sync_slave_enabled = ON;
slave> STOP SLAVE IO_THREAD; START SLAVE IO_THREAD;
3、確認半同步功能已經啓用
master> CREATE DATABASE magedudb;
master> SHOW STATUS LIKE 'Rpl_semi_sync_master_yes_tx';
slave> SHOW DATABASES;
三、MySQL Proxy
1、源碼安裝時，MySQL proxy的依賴關係：
libevent 1.x or higher (1.3b or later is preferred).
lua 5.1.x or higher.
glib2 2.6.0 or higher.
pkg-config.
libtool 1.5 or higher.
MySQL 5.0.x or higher developer files.
2、安裝
# tar zxf mysql-proxy-0.8.2.tar.gz
# cd mysql-proxy-0.8.2
# ./configure
# make
# make check
如果管理員有密碼，上面的步驟則需要使用如下格式進行：
# MYSQL_PASSWORD=root_pwd make check
# make install
默認情況下， mysql-proxy安裝在/usr/local/sbin/mysql-proxy，而Lua示例腳本安裝在/usr/local/share目錄中。
3、配置指令
mysql proxy的各配置參數請參見官方文檔，http://dev.mysql.com/doc/refman/5.6/en/mysql-proxy-configuration.html
使用rpm包在rhel6上安裝mysql-proxy-0.8.2，其會提供配置文件及服務腳本，但沒有提供讀寫分享的腳本。
/etc/sysconfig/mysql-proxy文件用於定義mysql-proxy的啓動參數。
ADMIN_USER – the user for the proxy's admin interface. You can leave the default admin user.
ADMIN_PASSWORD – the password for the admin user in clear text. Change the default password for better security.
ADMIN_LUA_SCRIPT – the admin script in the Lua programming language. Without this script the admin interface cannot work. You can leave the default value.
PROXY_USER – the system user under which the proxy will work. By default it is mysql-proxy, and it's safe to leave it as is.
PROXY_OPTIONS – proxy options such as logging level, plugins, and Lua scripts to be loaded.
其中PROXY_OPTIONS是最常用的一個選項，用於定義mysql-proxy工作時的重要參數，例如：
PROXY_OPTIONS="--daemon --log-level=info --log-use-syslog --plugins=proxy --plugins=admin --proxy-backend-addresses=192.168.1.102:3306 --proxy-read-only-backend-addresses=192.168.1.105:3306 --proxy-lua-script=/usr/lib/mysql-proxy/lua/proxy/rw-splitting.lua"
四、安裝配置mysql-proxy:
4.1 下載所需要的版本，這裏的系統平臺爲rhel6.4 32位系統，因此就以mysql-proxy-0.8.3-linux-glibc2.3-x86-32bit.tar.gz爲例。
# tar xf mysql-proxy-0.8.3-linux-glibc2.3-x86-32bit.tar.gz -C /usr/local
# cd /usr/local
# ln -sv mysql-proxy-0.8.3-linux-glibc2.3-x86-32bit mysql-proxy
添加代理用戶
# useradd mysql-proxy
4.2 爲mysql-proxy提供SysV服務腳本，內容如下所示
#!/bin/bash
#
# mysql-proxy This script starts and stops the mysql-proxy daemon
#
# chkconfig: - 78 30
# processname: mysql-proxy
# description: mysql-proxy is a proxy daemon for mysql
# Source function library.
. /etc/rc.d/init.d/functions
prog="/usr/local/mysql-proxy/bin/mysql-proxy"
# Source networking configuration.
if [ -f /etc/sysconfig/network ]; then
. /etc/sysconfig/network
fi
# Check that networking is up.
[ ${NETWORKING} = "no" ] && exit 0
# Set default mysql-proxy configuration.
ADMIN_USER="admin"
ADMIN_PASSWD="admin"
ADMIN_LUA_SCRIPT="/usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua"
PROXY_OPTIONS="--daemon"
PROXY_PID=/var/run/mysql-proxy.pid
PROXY_USER="mysql-proxy"
# Source mysql-proxy configuration.
if [ -f /etc/sysconfig/mysql-proxy ]; then
. /etc/sysconfig/mysql-proxy
fi
RETVAL=0
start() {
echo -n $"Starting $prog: "
daemon $prog $PROXY_OPTIONS --pid-file=$PROXY_PID --proxy-address="$PROXY_ADDRESS" --user=$PROXY_USER --admin-username="$ADMIN_USER" --admin-lua-script="$ADMIN_LUA_SCRIPT" --admin-password="$ADMIN_PASSWORD"
RETVAL=$?
echo
if [ $RETVAL -eq 0 ]; then
touch /var/lock/subsys/mysql-proxy
fi
}
stop() {
echo -n $"Stopping $prog: "
killproc -p $PROXY_PID -d 3 $prog
RETVAL=$?
echo
if [ $RETVAL -eq 0 ]; then
rm -f /var/lock/subsys/mysql-proxy
rm -f $PROXY_PID
fi
}
# See how we were called.
case "$1" in
start)
start
;;
stop)
stop
;;
restart)
stop
start
;;
condrestart|try-restart)
if status -p $PROXY_PIDFILE $prog >&/dev/null; then
stop
start
fi
;;
status)
status -p $PROXY_PID $prog
;;
*)
echo "Usage: $0 {start|stop|restart|reload|status|condrestart|try-restart}"
RETVAL=1
;;
esac
exit $RETVAL
將上述內容保存爲/etc/rc.d/init.d/mysql-proxy，給予執行權限，而後加入到服務列表。
# chmod +x /etc/rc.d/init.d/mysql-proxy
# chkconfig --add mysql-proxy
4.3 爲服務腳本提供配置文件/etc/sysconfig/mysql-proxy，內容如下所示：
# Options for mysql-proxy
ADMIN_USER="admin"
ADMIN_PASSWORD="admin"
ADMIN_ADDRESS=""
ADMIN_LUA_SCRIPT="/usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua"
PROXY_ADDRESS=""
PROXY_USER="mysql-proxy"
PROXY_OPTIONS="--daemon --log-level=info --log-use-syslog"
其中最後一行，需要按實際場景進行修改，例如：
PROXY_OPTIONS="--daemon --log-level=info --log-use-syslog --plugins=proxy --plugins=admin --proxy-backend-addresses=172.16.100.6:3306 --proxy-read-only-backend-addresses=172.16.100.7:3306 --proxy-lua-script=/usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua"
其中的proxy-backend-addresses選項和proxy-read-only-backend-addresses選項均可重複使用多次，以實現指定多個讀寫服務器或只讀服務器。
4.4 mysql-proxy的配置選項
mysql-proxy的配置選項大致可分爲幫助選項、管理選項、代理選項及應用程序選項幾類，下面一起去介紹它們。
--help
--help-admin
--help-proxy
--help-all ———— 以上四個選項均用於獲取幫助信息；
--proxy-address=host:port ———— 代理服務監聽的地址和端口；
--admin-address=host:port ———— 管理模塊監聽的地址和端口；
--proxy-backend-addresses=host:port ———— 後端mysql服務器的地址和端口；
--proxy-read-only-backend-addresses=host:port ———— 後端只讀mysql服務器的地址和端口；
--proxy-lua-script=file_name ———— 完成mysql代理功能的Lua腳本；
--daemon ———— 以守護進程模式啓動mysql-proxy；
--keepalive ———— 在mysql-proxy崩潰時嘗試重啓之；
--log-file=/path/to/log_file_name ———— 日誌文件名稱；
--log-level=level ———— 日誌級別；
--log-use-syslog ———— 基於syslog記錄日誌；
--plugins=plugin,.. ———— 在mysql-proxy啓動時加載的插件；
--user=user_name ———— 運行mysql-proxy進程的用戶；
--defaults-file=/path/to/conf_file_name ———— 默認使用的配置文件路徑；其配置段使用[mysql-proxy]標識；
--proxy-skip-profiling ———— 禁用profile；
--pid-file=/path/to/pid_file_name ———— 進程文件名；
5、複製如下內容建立admin.lua文件，將其保存至/usr/local/mysql-proxy/share/doc/mysql-proxy/目錄中。
--[[ $%BEGINLICENSE%$
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
$%ENDLICENSE%$ --]]
function set_error(errmsg)
proxy.response = {
type = proxy.MYSQLD_PACKET_ERR,
errmsg = errmsg or "error"
}
end
function read_query(packet)
if packet:byte() ~= proxy.COM_QUERY then
set_error("[admin] we only handle text-based queries (COM_QUERY)")
return proxy.PROXY_SEND_RESULT
end
local query = packet:sub(2)
local rows = { }
local fields = { }
if query:lower() == "select * from backends" then
fields = {
{ name = "backend_ndx",
type = proxy.MYSQL_TYPE_LONG },
{ name = "address",
type = proxy.MYSQL_TYPE_STRING },
{ name = "state",
type = proxy.MYSQL_TYPE_STRING },
{ name = "type",
type = proxy.MYSQL_TYPE_STRING },
{ name = "uuid",
type = proxy.MYSQL_TYPE_STRING },
{ name = "connected_clients",
type = proxy.MYSQL_TYPE_LONG },
}
for i = 1, #proxy.global.backends do
local states = {
"unknown",
"up",
"down"
}
local types = {
"unknown",
"rw",
"ro"
}
local b = proxy.global.backends[i]
rows[#rows + 1] = {
i,
b.dst.name, -- configured backend address
states[b.state + 1], -- the C-id is pushed down starting at 0
types[b.type + 1], -- the C-id is pushed down starting at 0
b.uuid, -- the MySQL Server's UUID if it is managed
b.connected_clients -- currently connected clients
}
end
elseif query:lower() == "select * from help" then
fields = {
{ name = "command",
type = proxy.MYSQL_TYPE_STRING },
{ name = "description",
type = proxy.MYSQL_TYPE_STRING },
}
rows[#rows + 1] = { "SELECT * FROM help", "shows this help" }
rows[#rows + 1] = { "SELECT * FROM backends", "lists the backends and their state" }
else
set_error("use 'SELECT * FROM help' to see the supported commands")
return proxy.PROXY_SEND_RESULT
end
proxy.response = {
type = proxy.MYSQLD_PACKET_OK,
resultset = {
fields = fields,
rows = rows
}
}
return proxy.PROXY_SEND_RESULT
end
6、測試
6.1 管理功能測試
# mysql -uadmin -padmin -h172.16.100.107 --port=4041
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.0.99-agent-admin
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> SELECT * FROM backends;
+-------------+-------------------+-------+------+------+-------------------+
| backend_ndx | address | state | type | uuid | connected_clients |
+-------------+-------------------+-------+------+------+-------------------+
| 1 | 172.16.100.6:3306 | up | rw | NULL | 0 |
| 2 | 172.16.100.7:3306 | up | ro | NULL | 0 |
+-------------+-------------------+-------+------+------+-------------------+
2 rows in set (0.00 sec)
6.2 讀寫分離測試
# mysql -uroot -pmagedu.com -h172.16.100.107 --port=4040
下面的讀寫分享腳本是由mysql-proxy-0.8.3提供了，將其複製保存爲/usr/lib/mysql-proxy/lua/proxy/rw-splitting.lua，就可以啓動服務了。
--[[ $%BEGINLICENSE%$
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