MogDB秘籍之乾坤大挪移

作者：老毛毛 | 来源：互联网 | 2023-06-08 11:15

前文“MogDB企业应用之七种武器”介绍了MogDB客户端七种驱动，文章末尾提到“除了武器之外MogDB的一些拳脚功夫”今天先填个“坑”。“乾坤大挪移”是明教呼叫神功，除了运劲巧妙

MogDB秘籍之乾坤大挪移

引子

前文“MogDB企业应用之七种武器”介绍了MogDB客户端七种驱动，文章末尾提到“除了武器之外MogDB的一些拳脚功夫”今天先填个“坑”。

“乾坤大挪移”是明教呼叫神功，除了运劲巧妙、善于挪移，乾坤大挪移更是集合了一切武功之大成，一法通，万法通，任何武功在他面前都已无秘奥之可言。不论哪一家哪一派的武功都能取而为用。在光明顶之战中，张无忌曾以乾坤大挪移复制了龙爪手，以同样的招式战胜了少林派四大神僧之一的空性。

江湖

虽说“乾坤大挪移”可以复制任何武功，但MogDB尚未修炼到“大圆满”境界，因此MogDB目前只能“复制”自家宗门的功法。

宗门与辈分

说“复制”自家宗门的功法，那就先聊聊宗门与辈分。

公元1986年，POSTGRES初出江湖经过六（6.0）代传人的努力，于1996年正是开宗立派“PostgreSQL”，版本号从6.0开始。

公元2020年6月30日，PostgreSQL第九（9.2.4）代传人自立门户创建了“openGauss”，号称改造了七层以上的门派功法（C–>C++）.

公元2020年9月30日，openGauss“大弟子”另立门派“MogDB”，MogDB属于江湖上势力最大的DBA“帮会”——云和恩墨，恩墨旗下门客众多，且各个身怀绝技。MogDB是云和恩墨基于openGauss开源数据库进行定制、推出的企业发行版。

三者属于同宗，从辈分上看MogDB的师傅是openGauss，师祖是PostgreSQL，所以MogDB的“乾坤大挪移”是可以复制其“师傅”和“师祖”的武功，同样可以借鉴或复制“师兄弟”、“师叔伯”（人大金仓、PolarDB-PG、TDSQL-PG、Vastbase等等）的武功。

功法

“乾坤大挪移”功法博大精深，复制“师傅”、“师祖”的功法还算灵光，但是如果想复制“师叔伯”、“师兄弟”的功法也并非易事，因为有些功法可能是“独创的绝学”。

下面主要介绍如何复制“师傅”、“师祖”的功法。

插件移植

移植openGauss

原则上相同内核版本的openGauss插件是直接可以在MogDB上使用的。所以从师傅哪里移植插件其实也谈不上复制。师傅有的徒弟都可以直接拿来用。

获取MogDB现有插件

wget https://cdn-mogdb.enmotech.com/mogdb-media/3.0.1/Plugins-3.0.1-openEuler-arm64.tar.gz
tar -zxvf Plugins-3.0.1-openEuler-arm64.tar.gz
cd plugins
ls -l

共10款插件，其中大部分是MogDB自己开发的插件。

查看openGauss现有插件

frank@DESKTOP-6NF3B9K:~/git/openGauss-server/contrib$ ll
total 288
drwxr-xr-x 67 frank frank 4096 May 20 21:22 ./
drwxr-xr-x 15 frank frank 4096 Aug 28 20:39 ../
-rw-r--r--  1 frank frank  693 May 20 21:22 .gitignore
-rw-r--r--  1 frank frank 1611 May 20 21:22 CMakeLists.txt
-rw-r--r--  1 frank frank 1141 May 20 21:22 Makefile
-rw-r--r--  1 frank frank 1133 May 20 21:22 README
drwxr-xr-x  2 frank frank 4096 May 20 21:22 adminpack/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 auth_delay/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 auto_explain/
drwxr-xr-x  4 frank frank 4096 May 20 21:22 btree_gin/
drwxr-xr-x  5 frank frank 4096 May 20 21:22 btree_gist/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 chkpass/
drwxr-xr-x  4 frank frank 4096 May 20 21:22 citext/
-rw-r--r--  1 frank frank   85 May 20 21:22 contrib-global.mk
drwxr-xr-x  5 frank frank 4096 May 20 21:22 cube/
drwxr-xr-x  5 frank frank 4096 May 20 21:22 dblink/
drwxr-xr-x  4 frank frank 4096 May 20 21:22 dict_int/
drwxr-xr-x  4 frank frank 4096 May 20 21:22 dict_xsyn/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 dummy_seclabel/
drwxr-xr-x  4 frank frank 4096 May 20 21:22 earthdistance/
drwxr-xr-x  5 frank frank 4096 May 20 21:22 file_fdw/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 fuzzystrmatch/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 gauss_connector/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 gc_fdw/
drwxr-xr-x  3 frank frank 4096 May 20 21:22 hdfs_fdw/
drwxr-xr-x  5 frank frank 4096 May 20 21:22 hstore/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 intagg/
drwxr-xr-x  6 frank frank 4096 May 20 21:22 intarray/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 isn/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 lo/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 log_fdw/
drwxr-xr-x  5 frank frank 4096 May 20 21:22 ltree/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 mppdb_decoding/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 mysql_fdw/
drwxr-xr-x  2 frank frank 4096 Aug 28 20:39 oid2name/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 oracle_fdw/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 pagehack/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 pageinspect/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 passwordcheck/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 pg_archivecleanup/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 pg_buffercache/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 pg_check_clog/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 pg_check_replslot/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 pg_freespacemap/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 pg_standby/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 pg_stat_statements/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 pg_test_fsync/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 pg_test_timing/
drwxr-xr-x  5 frank frank 4096 Aug 28 20:39 pg_trgm/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 pg_upgrade_support/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 pg_xlogdump/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 pgbench/
drwxr-xr-x  4 frank frank 4096 May 20 21:22 pgcrypto/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 pgrowlocks/
drwxr-xr-x  4 frank frank 4096 Aug 28 20:39 pgstattuple/
drwxr-xr-x  4 frank frank 4096 Aug 28 20:39 postgres_fdw/
drwxr-xr-x  3 frank frank 4096 May 20 21:22 roach_api/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 security_plugin/
drwxr-xr-x  5 frank frank 4096 May 20 21:22 seg/
drwxr-xr-x  4 frank frank 4096 May 20 21:22 sepgsql/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 spi/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 sql_decoding/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 sslinfo/
drwxr-xr-x  3 frank frank 4096 May 20 21:22 start-scripts/
drwxr-xr-x  5 frank frank 4096 May 20 21:22 tablefunc/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 tcn/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 test_decoding/
drwxr-xr-x  4 frank frank 4096 May 20 21:22 test_parser/
drwxr-xr-x  5 frank frank 4096 May 20 21:22 tsearch2/
drwxr-xr-x  4 frank frank 4096 May 20 21:22 unaccent/
drwxr-xr-x  2 frank frank 4096 May 20 21:22 vacuumlo/
drwxr-xr-x  4 frank frank 4096 May 20 21:22 xml2/

编译安装openGauss源码

我这有个一键编译安装openGauss源码的“秘籍”供大家参考，包括：

安装必备软件包

获取openGauss源码

获取openGauss第三方依赖包

编译openGauss源码

创建omm用户和dbgrp组

设置系统环境变量

初始化openGauss数据库

#! /bin/bash
set -e
# 安装依赖
yum install --skip-broken --allowerasing -y libaio-devel flex bison ncurses-devel glibc-devel patch readline-devel python3 python3-devel libaio-devel pam-devel libffi-devel golang autoconf automake cmake diffutils openssl-devel libtool libtool-devel bison-devel libatomic
mkdir git
cd git
# openGauss的代码仓库
# git clone https://gitee.com/xk_git_admin/openGauss-server.git
git clone https://gitee.com/opengauss/openGauss-server.git
# openGauss依赖的开源第三方软件仓库
# git clone https://gitee.com/xk_git_admin/openGauss-third_party.git openGauss-third_party
# git clone https://gitee.com/opengauss/openGauss-third_party.git openGauss-third_party
#cd openGauss-third_party/build
#sh build_all.sh
wget -c https://opengauss.obs.cn-south-1.myhuaweicloud.com/3.0.0/openGauss-third_party_binarylibs.tar.gz
tar -xzvf openGauss-third_party_binarylibs.tar.gz
mv openGauss-third_party_binarylibs binarylibs
cd openGauss-server
sh build.sh -m debug -3rd /root/git/binarylibs
make install
make clean
ulimit -n 655350
groupadd dbgrp
useradd omm -G dbgrp
cd 
mv git/ /home/omm
cd /home/omm
chown -R omm:dbgrp git
echo "export LD_LIBRARY_PATH=/home/omm/git/openGauss-server/mppdb_temp_install/lib:$LD_LIBRARY_PATH" >> /home/omm/.bashrc
echo "export PATH=/home/omm/git/openGauss-server/mppdb_temp_install/bin:$PATH" >> /home/omm/.bashrc
echo "export GAUSSHOME=/home/omm/data/single_node" >> home/omm/.bashrc
################
su - omm
cd /home/omm/git/openGauss-server/simpleInstall
sh install.sh -w "xk.XMX190035"

编译openGauss插件

[root@host-10-208-7-168 contrib]# cd /root/git/openGauss-server/contrib
[root@host-10-208-7-168 contrib]# make -j8
[root@host-10-208-7-168 citext]# cd citext
[root@host-10-208-7-168 citext]# ls
citext--1.0.sql  citext.control  citext.cpp  citext.so  citext--unpackaged--1.0.sql  expected  Makefile  sql
[root@host-10-208-7-168 citext]# make install
/usr/bin/mkdir -p &＃x27;/root/git/openGauss-server/mppdb_temp_install/share/postgresql/extension&＃x27;
/usr/bin/mkdir -p &＃x27;/root/git/openGauss-server/mppdb_temp_install/share/postgresql/extension&＃x27;
/usr/bin/mkdir -p &＃x27;/root/git/openGauss-server/mppdb_temp_install/lib/postgresql&＃x27;
/bin/sh ../../config/install-sh -c -m 644 ./citext.control &＃x27;/root/git/openGauss-server/mppdb_temp_install/share/postgresql/extension/&＃x27;
/bin/sh ../../config/install-sh -c -m 644 ./citext--1.0.sql ./citext--unpackaged--1.0.sql  &＃x27;/root/git/openGauss-server/mppdb_temp_install/share/postgresql/extension/&＃x27;
/bin/sh ../../config/install-sh -c -m 755  citext.so &＃x27;/root/git/openGauss-server/mppdb_temp_install/lib/postgresql/&＃x27;

注：可以在/root/git/openGauss-server/contrib 编译所有插件，也可以进入到具体插件目录进行单独编译。

以citext插件为例，该插件需要将citext.control 和citext--1.0.sql copy到$GAUSS_HOME/share/postgresql/extension下，将citext.socopy到$GAUSS_HOME/lib/postgresql下。

安装MogDB

这里用最简单的PTK方法安装：

安装PTK

[root@host-10-208-7-168 ~]# curl --proto &＃x27;=https&＃x27; --tlsv1.2 -sSf https://cdn-mogdb.enmotech.com/ptk/install.sh | sh
Downloading ptk package...
Detected shell: bash
Shell profile:  /root/.bash_profile
ptk has been added to PATH in /root/.bash_profile
open a new terminal or source /root/.bash_profile to active it
Installed path: /root/.ptk/bin/ptk
[root@host-10-208-7-168 ~]# source /root/.bash_profile

编辑配置文件config.yaml

[root@host-10-208-7-168 ~]# cat config.yaml
# config.yaml
global:
    cluster_name: mogdb1
    user: omm
    group: omm
    base_dir: /opt/mogdb
db_servers:
    - host: 127.0.0.1
      db_port: 26000

主机设置检查

ptk checkos -f config.yaml

Q：有两个错误

A：1.关闭防火墙；2.关闭大页内存

systemctl stop firewalld.service
systemctl disable firewalld.service
echo never >/sys/kernel/mm/transparent_hugepage/enabled
# 如果出现A6.Check_SysCtl_Parameter         | Abnormal，则使用下面方法{in Kylin 10 sp1}
echo "RemoveIPC=no" >> /etc/systemd/logind.conf

再次检查

ptk checkos -f config.yaml

注：warning可以暂时不处理

执行安装

ptk install -f config.yaml

切换omm用户

su - omm

执行pg_config，查看相关信息

[omm@host-10-208-7-168 ~]$ pg_config
BINDIR = /opt/mogdb/app/bin
DOCDIR = /opt/mogdb/app/share/doc/postgresql
HTMLDIR = /opt/mogdb/app/share/doc/postgresql
INCLUDEDIR = /opt/mogdb/app/include
PKGINCLUDEDIR = /opt/mogdb/app/include/postgresql
INCLUDEDIR-SERVER = /opt/mogdb/app/include/postgresql/server
LIBDIR = /opt/mogdb/app/lib
PKGLIBDIR = /opt/mogdb/app/lib/postgresql
LOCALEDIR = /opt/mogdb/app/share/locale
MANDIR = /opt/mogdb/app/share/man
SHAREDIR = /opt/mogdb/app/share/postgresql
SYSCOnFDIR= /opt/mogdb/app/etc/postgresql

其中PKGLIBDIR = /opt/mogdb/app/lib/postgresql 和SHAREDIR = /opt/mogdb/app/share/postgresql 是存放插件相关文件的目录。

手动移植openGauss插件到MogDB插件目录

[root@host-10-208-7-168 citext]# cp citext.so /opt/mogdb/app/lib/postgresql
[root@host-10-208-7-168 citext]# chown omm:omm /opt/mogdb/app/lib/postgresql/citext.so
[root@host-10-208-7-168 citext]# cp citext.control citext--1.0.sql /opt/mogdb/app/share/postgresql/extension/
[root@host-10-208-7-168 citext]# chown omm:omm /opt/mogdb/app/share/postgresql/extension/citext.control
[root@host-10-208-7-168 citext]# chown omm:omm /opt/mogdb/app/share/postgresql/extension/citext--1.0.sql

移植插件

当前插件

MogDB=# \dx
                               List of installed extensions
      Name       | Version |   Schema   |                   Description
-----------------+---------+------------+--------------------------------------------------
 dist_fdw        | 1.0     | pg_catalog | foreign-data wrapper for distfs access
 file_fdw        | 1.0     | pg_catalog | foreign-data wrapper for flat file access
 hdfs_fdw        | 1.0     | pg_catalog | foreign-data wrapper for flat file access
 hstore          | 1.1     | pg_catalog | data type for storing sets of (key, value) pairs
 log_fdw         | 1.0     | pg_catalog | Foreign Data Wrapper for accessing logging data
 mot_fdw         | 1.0     | pg_catalog | foreign-data wrapper for MOT access
 plpgsql         | 1.0     | pg_catalog | PL/pgSQL procedural language
 security_plugin | 1.0     | pg_catalog | provides security functionality
(8 rows)

可用插件，可以看到移植过来的citext插件。

MogDB=# create extension citext;
CREATE EXTENSION
MogDB=# \dx
                               List of installed extensions
      Name       | Version |   Schema   |                   Description
-----------------+---------+------------+--------------------------------------------------
 citext          | 1.0     | public     | data type for case-insensitive character strings
 dist_fdw        | 1.0     | pg_catalog | foreign-data wrapper for distfs access
 file_fdw        | 1.0     | pg_catalog | foreign-data wrapper for flat file access
 hdfs_fdw        | 1.0     | pg_catalog | foreign-data wrapper for flat file access
 hstore          | 1.1     | pg_catalog | data type for storing sets of (key, value) pairs
 log_fdw         | 1.0     | pg_catalog | Foreign Data Wrapper for accessing logging data
 mot_fdw         | 1.0     | pg_catalog | foreign-data wrapper for MOT access
 plpgsql         | 1.0     | pg_catalog | PL/pgSQL procedural language
 security_plugin | 1.0     | pg_catalog | provides security functionality
(9 rows)

测试插件

MogDB=# SELECT &＃x27;a&＃x27;::citext = &＃x27;a&＃x27;::citext AS t;
 t
---
 t
(1 row)
MogDB=# SELECT &＃x27;a&＃x27;::citext = &＃x27;b&＃x27;::citext AS f;
 f
---
 f
(1 row)
MogDB=# SELECT &＃x27;a&＃x27;::citext = &＃x27;ab&＃x27;::citext AS f;
 f
---
 f
(1 row)
MogDB=# SELECT &＃x27;a&＃x27;::citext <> &＃x27;ab&＃x27;::citext AS t;
 t
---
 t
(1 row)

移植PostgreSQL

查看现有PostgreSQL的插件列表

[root@host-10-208-7-168 contrib]# pwd
/root/git/postgres/contrib
[root@host-10-208-7-168 contrib]# ll
total 248K
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 adminpack
drwxr-xr-x 5 root root 4.0K Sep  4 12:23 amcheck
drwxr-xr-x 2 root root 4.0K Sep  4 12:23 auth_delay
drwxr-xr-x 3 root root 4.0K Sep  4 12:23 auto_explain
drwxr-xr-x 3 root root 4.0K Sep  4 12:23 basebackup_to_shell
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 basic_archive
drwxr-xr-x 5 root root 4.0K Sep  4 12:23 bloom
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 bool_plperl
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 btree_gin
drwxr-xr-x 5 root root 4.0K Sep  4 12:23 btree_gist
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 citext
-rw-r--r-- 1 root root   85 Sep  4 12:23 contrib-global.mk
drwxr-xr-x 5 root root 4.0K Sep  4 12:23 cube
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 dblink
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 dict_int
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 dict_xsyn
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 earthdistance
drwxr-xr-x 5 root root 4.0K Sep  4 12:23 file_fdw
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 fuzzystrmatch
drwxr-xr-x 5 root root 4.0K Sep  4 12:23 hstore
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 hstore_plperl
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 hstore_plpython
drwxr-xr-x 2 root root 4.0K Sep  4 12:23 intagg
drwxr-xr-x 6 root root 4.0K Sep  4 12:23 intarray
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 isn
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 jsonb_plperl
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 jsonb_plpython
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 lo
drwxr-xr-x 5 root root 4.0K Sep  4 12:23 ltree
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 ltree_plpython
-rw-r--r-- 1 root root 1.6K Sep  4 12:23 Makefile
drwxr-xr-x 3 root root 4.0K Sep  4 12:23 oid2name
drwxr-xr-x 2 root root 4.0K Sep  4 12:23 old_snapshot
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 pageinspect
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 passwordcheck
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 pg_buffercache
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 pgcrypto
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 pg_freespacemap
drwxr-xr-x 3 root root 4.0K Sep  4 12:23 pg_prewarm
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 pgrowlocks
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 pg_stat_statements
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 pgstattuple
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 pg_surgery
drwxr-xr-x 5 root root 4.0K Sep  4 12:23 pg_trgm
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 pg_visibility
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 pg_walinspect
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 postgres_fdw
-rw-r--r-- 1 root root 1.2K Sep  4 12:23 README
drwxr-xr-x 5 root root 4.0K Sep  4 12:23 seg
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 sepgsql
drwxr-xr-x 2 root root 4.0K Sep  4 12:26 spi
drwxr-xr-x 2 root root 4.0K Sep  4 12:23 sslinfo
drwxr-xr-x 3 root root 4.0K Sep  4 12:23 start-scripts
drwxr-xr-x 5 root root 4.0K Sep  4 12:23 tablefunc
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 tcn
drwxr-xr-x 6 root root 4.0K Sep  4 12:23 test_decoding
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 tsm_system_rows
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 tsm_system_time
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 unaccent
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 uuid-ossp
drwxr-xr-x 3 root root 4.0K Sep  4 12:23 vacuumlo
drwxr-xr-x 4 root root 4.0K Sep  4 12:23 xml2

如上节openGauss已经迁移了几乎所有PostgreSQL的插件，所以现有PostgreSQL的插件几乎都可以从openGauss上移植到MogDB，那么我们用一个自己实现的PostgreSQL插件进行移植。

编译安装postgres

git clone https://github.com/postgres/postgres.git
cd postgres/
./configure --prefix=/root/pgsql
make -j8
make install

编译PostgreSQL插件

可以参考之前的一篇文章“postgresql自定义函数实现，通过contrib模块进行扩展”，这里就简单介绍一下过程。

主要过程：

编写c代码

编写.sql文件

编写.control文件

编写Makefile

编译

安装

验证

移植插件

敲黑板，划重点。这个是本文的重点。

之前一篇文章是在MogDB上直接开发插件可以参考“openGauss/MogDB调用C FUNCTION”，这里主要将移植的注意事项。

核心差异

PostgreSQL以C开发，MogDB/openGauss以C++，导出符号时可能存在ABI不兼容的问题。因此开发插件时C++代码需要使用extern "C"

编译是需要使用g++代替gcc。（如果使用cmake，需要把.c后缀还差.cpp，从而自动识别编译器）

extern "C" Datum add_ab(PG_FUNCTION_ARGS);

分享一个MogDB/openGauss插件编译的CMakeLists.txt。

cmake_minimum_required (VERSION 2.8)
project (gs_plug)
set(CMAKE_CXX_FLAGS "-Wall -std=c++11 -Wall")
set(CMAKE_CXX_FLAGS_DEBUG "-g3")
set(CMAKE_CXX_FLAGS_RELEASE "-O2")
set(CMAKE_BUILD_TYPE Debug)
set(MOG_INCLUDE /opt/mogdb/app/include/postgresql/server)
set(MOG_LIBPATH /opt/mogdb/app/lib/postgresql)
set(MOG_EXTENSION /opt/mogdb/app/share/postgresql/extension)
include_directories(${MOG_INCLUDE})
aux_source_directory(. DIR_SRCS)
add_library (${PROJECT_NAME} SHARED ${DIR_SRCS})
install(TARGETS ${PROJECT_NAME} DESTINATION ${MOG_LIBPATH})

安装

cp *.control *.sql /opt/mogdb/app/share/postgresql/extension/
cp *.so /opt/mogdb/app/lib/postgresql/

测试插件

安装前状态

安装插件

测试插件

以上关于PostgreSQL插件移植到MogDB算是抛砖引玉吧。PostgreSQL有着丰富的插件，大部分是非官方的。推荐个网站给大家，可以自己动手试试迁移。

https://pgxn.org/

MogDB插件安装工具

可以参考前文“openGauss/MogDB脚本源码浅析（2）—— gs_install_plugin/gs_install_plugin_local”，介绍了如何通过gs_install_plugin_local迁移openGauss的插件。

以lo插件为例，进行迁移

[omm@host-10-208-76-194 plugins]$ cd  /opt/mogdb/tool/script/static/plugins/plugins
[omm@host-10-208-76-194 plugins]$ ls
dblink  desc.json  dolphin  orafce  pg_bulkload  pg_prewarm  pg_repack  pg_trgm  postgis  wal2json  whale
[omm@host-10-208-76-194 plugins]$ mkdir lo
[omm@host-10-208-76-194 plugins]$ ls
dblink  desc.json  dolphin  lo  orafce  pg_bulkload  pg_prewarm  pg_repack  pg_trgm  postgis  wal2json  whale
[omm@host-10-208-76-194 plugins]$

将openGauss插件复制到MogDB插件目录，并修改属组

[root@host-10-208-76-194 lo]# cp lo.so lo.control lo--1.0.sql /opt/mogdb/tool/script/static/plugins/plugins/lo
[root@host-10-208-76-194 lo]# chown -R omm:omm /opt/mogdb/tool/script/static/plugins/plugins/lo

修改desc.json

重新打包

tar -zcvf Plugins-3.0.1-openEuler-arm64.tar.gz plugins/

注：这里重新打包有点麻烦，也可以修改代码，注释掉解压的步骤，或者优雅一点，则可以增加参数控制是否重新解压，如果不重新打包则解压是desc.json会被覆盖成老版本，导致安装新插件失败。

总结

希望这篇文章能把PostgreSQL、openGauss和MogDB关于插件开发和迁移相关的问题能够尽量的讲清晰，需要结合之前的几篇（“postgresql自定义函数实现，通过contrib模块进行扩展”、“openGauss/MogDB调用C FUNCTION”、“openGauss/MogDB脚本源码浅析（2）—— gs_install_plugin/gs_install_plugin_local”）文章一起学习了解。