ShardingSphere-proxy +PostgreSQL implements read-write separation (static strategy)

In business, the database is read more and written less,And the performance of a single server or a single database can no longer satisfy the current business when a large number of database read requests are made,We may need to do it to the database读写分离.

Common tools that can do read-write separation aremycat、ShardingSphere等.本文使用ShardingSphere-proxy实现了PostgreSQL的读写分离场景,如果对于PostgreSQLIn addition to read-write separation, the database also requires connection pooling and other requirements,还可以了解一下PostgreSQL的pgpool-II.

一、本文相关ip地址

角色	版本	IP地址
主库	PostgreSQL 13.4	172.20.10.9
从库	PostgreSQL 13.4	172.20.10.10
ShardingSphere-proxy	5.1.2	172.20.10.3
用于测试连接ShardingSphere-Proxy（有psql客户端）	psql版本 12.9	172.20.10.6

本次安装部署是在CentOS Linux release 7.4上完成,It has already been deployedPostgreSQLmaster-slave streaming replication environment.在此不做赘述.

[[email protected] ~]$ psql -c "select * from pg_stat_replication;"  pid  | usesysid | usename | application_name | client_addr  | client_hostname | client_port |         backend_start         | backend_xmin |   state   |  sent_lsn  | write_lsn  | flush_lsn  | replay_lsn |    write_lag    | flush_lag | replay_lag | sync_priority | sync_state |          reply_time          -------+----------+---------+------------------+--------------+-----------------+-------------+-------------------------------+--------------+-----------+------------+------------+------------+------------+-----------------+-----------+------------+---------------+------------+------------------------------ 56107 |    16385 | replica | walreceiver      | 172.20.10.10 |                 |       46262 | 2022-08-02 12:02:49.504343+08 |              | streaming | 0/FB841B40 | 0/FB841B40 | 0/FB841B40 | 0/FB841B40 | 00:00:00.037914 |           |            |             0 | async      | 2022-08-02 12:02:49.65561+08(1 row)

二、数据库配置

1.postgresql.conf里配置

listen_addresses = '*' 

2.pg_hba.conf白名单配置（Here is my test for convenience,如果实际使用,It is best to use the smallest range practicalipsegment to constrain）

host    all             all             0.0.0.0/0            md5

重启数据库

3.Created in the database for testingShardingSphere-proxyRead-write separation of user and database（Permissions are also constrained when used,can be given to the databaseowner,Or adjust as needed）

create user ssp_user_test password '[email protected]' superuser;create database ssp_db_test;

三、安装部署ShardingSphere-proxy

在172.20.10.3节点安装proxy

需要安装jdk（must have Java JRE 8 or higher）,我本地的jdk版本为

[[email protected] conf]# java -versionopenjdk version "1.8.0_342"OpenJDK Runtime Environment (build 1.8.0_342-b07)OpenJDK 64-Bit Server VM (build 25.342-b07, mixed mode)

1.Get the package and install itShardingSphere-proxy

--下载地址https://shardingsphere.apache.org/document/current/en/downloads/--解压tar -xvf apache-shardingsphere-5.1.2-shardingsphere-proxy-bin.tar.gz--做软链ln -s /root/apache-shardingsphere-5.1.2-shardingsphere-proxy-bin /opt/ssp

2.修改server.yaml,Configure the virtual account password

Configure the virtual account password,使用默认的root用户及密码root,And allow external network connection,Also permissions are specified as “All permissions are unlimited”,sql-showis used to record each entry in the logsqland the executing node,Others are default values

rules:  - !AUTHORITY    users:      - [email protected]%:root#      - [email protected]:sharding    provider:      type: type: ALL_PERMITTEDprops:#  max-connections-size-per-query: 1#  kernel-executor-size: 16  # Infinite by default.#  proxy-frontend-flush-threshold: 128  # The default value is 128.#  proxy-hint-enabled: false  sql-show: on

如图所示

3.Edit read-write separated files config-readwrite-splitting.yaml

databaseNameis my mapped database name,primary_ds和replica_ds_0respectively as the main library/Write the relevant configuration of the library and the slave library/Read library dependencies are configured.

databaseName: xmaster_db#dataSources:  primary_ds:    url: jdbc:postgresql://172.20.10.9:5432/ssp_db_test    username: ssp_user_test    password: [email protected]#    connectiontimeoutMilliseconds: 30000#    idletimeoutmilliseconds: 60000#    maxlifetimemilliseconds: 1800000#    maxpoolsize: 50#   minpoolsize: 1  replica_ds_0:    url: jdbc:postgresql://172.20.10.10:5432/ssp_db_test    username: ssp_user_test    password: [email protected]:- !READWRITE_SPLITTING  dataSources:    readwrite_ds:      type: Static      props:        write-data-source-name: primary_ds        read-data-source-names: replica_ds_0

四、启动ShardingSphere-proxy并验证

[[email protected] bin]# pwd/root/apache-shardingsphere-5.1.2-shardingsphere-proxy-bin/bin[[email protected] bin]# sh start.sh we find java version: java8, full_version=1.8.0_342Starting the ShardingSphere-Proxy ...The classpath is /root/apache-shardingsphere-5.1.2-shardingsphere-proxy-bin/conf:.:/root/apache-shardingsphere-5.1.2-shardingsphere-proxy-bin/lib/*:/root/apache-shardingsphere-5.1.2-shardingsphere-proxy-bin/ext-lib/*Please check the STDOUT file: /root/apache-shardingsphere-5.1.2-shardingsphere-proxy-bin/logs/stdout.log

查看ShardingSphere-proxy输出的日志内容

[[email protected] bin]# cat /root/apache-shardingsphere-5.1.2-shardingsphere-proxy-bin/logs/stdout.logThanks for using Atomikos! This installation is not registered yet. REGISTER FOR FREE at http://www.atomikos.com/Main/RegisterYourDownload and receive:- tips & advice - working demos - access to the full documentation - special exclusive bonus offers not available to others - everything you need to get the most out of using Atomikos![INFO ] 2022-07-07 20:18:07.629 [main] o.a.s.p.v.ShardingSphereProxyVersion - Database name is `PostgreSQL`, version is `13.4`, database name is `xmaster_db`[INFO ] 2022-07-07 20:18:07.889 [main] o.a.s.p.frontend.ShardingSphereProxy - ShardingSphere-Proxy Memory mode started successfullyThanks for using Atomikos! This installation is not registered yet. REGISTER FOR FREE at http://www.atomikos.com/Main/RegisterYourDownload and receive:- tips & advice - working demos - access to the full documentation - special exclusive bonus offers not available to others - everything you need to get the most out of using Atomikos![INFO ] 2022-07-07 20:19:27.088 [main] o.a.s.p.v.ShardingSphereProxyVersion - Database name is `PostgreSQL`, version is `13.4`, database name is `xmaster_db`[INFO ] 2022-07-07 20:19:27.349 [main] o.a.s.p.frontend.ShardingSphereProxy - ShardingSphere-Proxy Memory mode started successfully

ShardingSphere-Proxy已经启动起来了.ShardingSphere-Proxy的默认端口3307也已经起来了

[[email protected] bin]# ss -tnlState       Recv-Q Send-Q       Local Address:Port                      Peer Address:Port              LISTEN      0      128                      *:6000                                 *:*                  LISTEN      0      128                      *:22                                   *:*                  LISTEN      0      128                     :::3307                                :::*                  LISTEN      0      128                     :::6000                                :::*                  LISTEN      0      128                     :::22                                  :::*  

At this time we pass another terminal,进行连接验证,Namely our fourth server172.20.10.6,通过server.yamlvirtual account password,can be connected

[[email protected] ~]$ ip a | grep ens33 | grep global    inet 172.20.10.6/28 brd 172.20.10.15 scope global ens33[[email protected] ~]$ psql -h 172.20.10.3  -U root xmaster_db -p 3307Password for user root: psql (12.9, server 13.4-ShardingSphere-Proxy 5.1.2)WARNING: psql major version 12, server major version 13.         Some psql features might not work.Type "help" for help.xmaster_db=> create table t1(id int);CREATE TABLExmaster_db=> insert into t1 values(1);INSERT 0 1xmaster_db=> select * from t1; id ----  1(1 row)

During data insertion, you can go to the main database of the database to view the data status

ssp_db_test=# \dt           List of relations Schema | Name | Type  |     Owner     --------+------+-------+--------------- public | t1   | table | ssp_user_test(1 row)ssp_db_test=# select * from t1; id ----  1(1 row)ssp_db_test=# select * from t1;ERROR:  relation "t1" does not existLINE 1: select * from t1;                      ^ssp_db_test=# \dtDid not find any relations.

去查看ShardingSphere-proxy的输出日志,发现create、insert、dropAll operations are performed on the master node,而selectExecute on the standby node.

[[email protected] logs]# ll /root/apache-shardingsphere-5.1.2-shardingsphere-proxy-bin/logs/stdout.log -rw-r--r-- 1 root root 4926 Aug  2 14:46 /root/apache-shardingsphere-5.1.2-shardingsphere-proxy-bin/logs/stdout.log

[INFO ] 2022-08-02 14:45:26.965 [Connection-2-ThreadExecutor] ShardingSphere-SQL - Logic SQL: create table t1(id int);[INFO ] 2022-08-02 14:45:26.965 [Connection-2-ThreadExecutor] ShardingSphere-SQL - SQLStatement: PostgreSQLCreateTableStatement(containsNotExistClause=false)[INFO ] 2022-08-02 14:45:26.965 [Connection-2-ThreadExecutor] ShardingSphere-SQL - Actual SQL: primary_ds ::: create table t1(id int);[INFO ] 2022-08-02 14:45:29.655 [Connection-2-ThreadExecutor] ShardingSphere-SQL - Logic SQL: insert into t1 values(1);[INFO ] 2022-08-02 14:45:29.655 [Connection-2-ThreadExecutor] ShardingSphere-SQL - SQLStatement: PostgreSQLInsertStatement(withSegment=Optional.empty)[INFO ] 2022-08-02 14:45:29.655 [Connection-2-ThreadExecutor] ShardingSphere-SQL - Actual SQL: primary_ds ::: insert into t1 values(1);[INFO ] 2022-08-02 14:45:31.953 [Connection-2-ThreadExecutor] ShardingSphere-SQL - Logic SQL: select * from t1;[INFO ] 2022-08-02 14:45:31.953 [Connection-2-ThreadExecutor] ShardingSphere-SQL - SQLStatement: PostgreSQLSelectStatement(limit=Optional.empty, lock=Optional.empty, window=Optional.empty)[INFO ] 2022-08-02 14:45:31.953 [Connection-2-ThreadExecutor] ShardingSphere-SQL - Actual SQL: replica_ds_0 ::: select * from t1;[INFO ] 2022-08-02 14:46:00.073 [Connection-2-ThreadExecutor] ShardingSphere-SQL - Logic SQL: drop table t1;[INFO ] 2022-08-02 14:46:00.073 [Connection-2-ThreadExecutor] ShardingSphere-SQL - SQLStatement: PostgreSQLDropTableStatement(containsExistClause=false)[INFO ] 2022-08-02 14:46:00.073 [Connection-2-ThreadExecutor] ShardingSphere-SQL - Actual SQL: primary_ds ::: drop table t1;