云贝教育 |【PostgreSQL PGCA】pg15安装pg_hint_plan扩展包
pg15安装pg_hint_plan扩展包
pg当前是支持HINT固定执行计划，需要通过扩展包pg_hint_plan来实现
一、扩展包下载：
Releases · ossc-db/pg_hint_plan · GitHub
二、选择v15版本
pg_hint_plan15 1.5.1 is released
pg_hint_plan15 1.5.1 is released. This version only supports PostgreSQL 15.
Some changes are made in this release:
Fix hint stack corruption on ERROR when setting GUCs from Set hints (Michael Paquier: 61a3a55)
Fix handling of unavailable indexes in Scan hints (Sami Imseih: 33adb40)
Reset more aggressively hints for queries executed via extended query protocol (tanujnay112: de709e6)
Add EXPLAIN (COSTS false) to some tests (Masahiro Ikeda: ffd7f62)
Bootstrap a new documentation (Julien Rouhaud: 287e9b5, and more). This removes the HTML documentation, switching to a set of markdown files with support for multiple languages possible.
Fix and improve documentation (Michael Paquier: ea8616b)下载源码包（任选其一）
三、上传postgres用户下
[postgres@ora19c02 ~]$ ll -d pg_hint_plan-REL15_1_5_1.zip
-rw-r--r-- 1 postgres postgres 227951 Nov 1 15:21 pg_hint_plan-REL15_1_5_1.zip四、解压包
unzip pg_hint_plan-REL15_1_5_1.zip五、进入解压目录，并编绎
[postgres@ora19c02 pg_hint_plan-REL15_1_5_1]$ make
[postgres@ora19c02 pg_hint_plan-REL15_1_5_1]$ make install编绎可能会碰到的问题:
1）make时提示命令找不到
/bin/sh: rpmbuild: command not found
解决
yum install rpm-build2）权限不足
[postgres@ora19c02 pg_hint_plan-REL15_1_5_1]$ make install
/usr/bin/mkdir -p '/usr/local/postgres/share/extension'
/usr/bin/mkdir -p '/usr/local/postgres/share/extension'
/usr/bin/mkdir -p '/usr/local/postgres/lib'
/usr/bin/install -c -m 644 .//pg_hint_plan.control '/usr/local/postgres/share/extension/'
/usr/bin/install: cannot create regular file ‘/usr/local/postgres/share/extension/pg_hint_plan.control’: Permission denied
make: *** [install] Error 1授权解决
[root@ora19c02 ]# chmod 777 /usr/local/postgres -R六、验证安装
[postgres@ora19c02 pg_hint_plan-REL15_1_5_1]$ ls -l /usr/local/postgres/lib/ | grep hint
-rwxr-xr-x 1 postgres postgres 357016 Nov 1 15:31 pg_hint_plan.so
[postgres@ora19c02 pg_hint_plan-REL15_1_5_1]$ ls -l /usr/local/postgres/share/extension/ | grep hint
-rw-r--r-- 1 postgres postgres 437 Nov 1 15:31 pg_hint_plan--1.3.0--1.3.1.sql
-rw-r--r-- 1 postgres postgres 684 Nov 1 15:31 pg_hint_plan--1.3.0.sql
-rw-r--r-- 1 postgres postgres 437 Nov 1 15:31 pg_hint_plan--1.3.1--1.3.2.sql
-rw-r--r-- 1 postgres postgres 437 Nov 1 15:31 pg_hint_plan--1.3.2--1.3.3.sql
-rw-r--r-- 1 postgres postgres 437 Nov 1 15:31 pg_hint_plan--1.3.3--1.3.4.sql
-rw-r--r-- 1 postgres postgres 437 Nov 1 15:31 pg_hint_plan--1.3.4--1.3.5.sql
-rw-r--r-- 1 postgres postgres 437 Nov 1 15:31 pg_hint_plan--1.3.5--1.3.6.sql
-rw-r--r-- 1 postgres postgres 437 Nov 1 15:31 pg_hint_plan--1.3.6--1.3.7.sql
-rw-r--r-- 1 postgres postgres 437 Nov 1 15:31 pg_hint_plan--1.3.7--1.3.8.sql
-rw-r--r-- 1 postgres postgres 437 Nov 1 15:31 pg_hint_plan--1.3.8--1.3.9.sql
-rw-r--r-- 1 postgres postgres 433 Nov 1 15:31 pg_hint_plan--1.3.9--1.4.sql
-rw-r--r-- 1 postgres postgres 437 Nov 1 15:31 pg_hint_plan--1.4.1--1.4.2.sql
-rw-r--r-- 1 postgres postgres 435 Nov 1 15:31 pg_hint_plan--1.4--1.4.1.sql
-rw-r--r-- 1 postgres postgres 434 Nov 1 15:31 pg_hint_plan--1.4.2--1.5.sql
-rw-r--r-- 1 postgres postgres 436 Nov 1 15:31 pg_hint_plan--1.5--1.5.1.sql
-rw-r--r-- 1 postgres postgres 104 Nov 1 15:31 pg_hint_plan.control七、设置插件
7.1 会话级别设置
postgres=# LOAD 'pg_hint_plan';
LOAD如果报错，在template1数据库下执行以下SQL
testdb=# \c template1
template1=# create extension pg_hint_plan;
CREATE EXTENSION7.2 用户级别设置
postgres=# alter user postgres set session_preload_libraries='pg_hint_plan';
ALTER ROLE7.3 数据库级别设置
postgres=# alter database postgres set session_preload_libraries='pg_hint_plan';
ALTER DATABASE7.4 集群级别设置
修改参数文件
[postgres@ora19c02 data]$ vi postgresql.conf
shared_preload_libraries = 'pg_hint_plan' # (change requires restart)重启数据库
pg_ctl restart7.5 重置配置
配置错了的话就连不上数据库，如果配置错了，连接template1库执行
alter database postgres reset session_preload_libraries;
alter user postgres reset session_preload_libraries;
八、测试HINT功能
8.1 查看参数
testdb=# show session_preload_libraries;
session_preload_libraries
---------------------------
pg_hint_plan8.2 、模拟数据
CREATE TABLE
IF NOT EXISTS dept (
-- 部门编号
deptno serial PRIMARY KEY,
-- 部门名称
dname VARCHAR (15),
-- 部门所在位置
loc VARCHAR (50)
);
CREATE TABLE
IF NOT EXISTS emp (
-- 雇员编号
empno serial,
-- 雇员姓名
ename VARCHAR (15),
-- 雇员职位
job VARCHAR (10),
-- 雇员对应的领导的编号
mgr INT,
-- 雇员的雇佣日期
hiredate DATE,
-- 雇员的基本工资
sal DECIMAL (7, 2),
-- 奖金
comm DECIMAL (7, 2),
-- 所在部门
deptno INT,
FOREIGN KEY (deptno) REFERENCES dept (deptno)
);
-- dept表中的数据
INSERT INTO dept VALUES (10,'ACCOUNTING','NEW YORK');
INSERT INTO dept VALUES (20,'RESEARCH','DALLAS');
INSERT INTO dept VALUES (30,'SALES','CHICAGO');
INSERT INTO dept VALUES (40,'OPERATIONS','BOSTON');
-- emp表中的数据
INSERT INTO emp VALUES (7369,'SMITH','CLERK',7902,to_date('1980-12-17','yyyy-mm-dd'),800,NULL,20);
INSERT INTO emp VALUES (7499,'ALLEN','SALESMAN',7698,to_date('1981-2-20','yyyy-mm-dd'),1600,300,30);
INSERT INTO emp VALUES (7521,'WARD','SALESMAN',7698,to_date('1981-2-22','yyyy-mm-dd'),1250,500,30);
INSERT INTO emp VALUES (7566,'JONES','MANAGER',7839,to_date('1981-4-2','yyyy-mm-dd'),2975,NULL,20);
INSERT INTO emp VALUES (7654,'MARTIN','SALESMAN',7698,to_date('1981-9-28','yyyy-mm-dd'),1250,1400,30);
INSERT INTO emp VALUES (7698,'BLAKE','MANAGER',7839,to_date('1981-5-1','yyyy-mm-dd'),2850,NULL,30);
INSERT INTO emp VALUES (7782,'CLARK','MANAGER',7839,to_date('1981-6-9','yyyy-mm-dd'),2450,NULL,10);
INSERT INTO emp VALUES (7788,'SCOTT','ANALYST',7566,to_date('87-7-13','yyyy-mm-dd'),3000,NULL,20);
INSERT INTO emp VALUES (7839,'KING','PRESIDENT',NULL,to_date('1981-11-17','yyyy-mm-dd'),5000,NULL,10);
INSERT INTO emp VALUES (7844,'TURNER','SALESMAN',7698,to_date('1981-9-8','yyyy-mm-dd'),1500,0,30);
INSERT INTO emp VALUES (7876,'ADAMS','CLERK',7788,to_date('87-7-13','yyyy-mm-dd'),1100,NULL,20);
INSERT INTO emp VALUES (7900,'JAMES','CLERK',7698,to_date('1981-12-3','yyyy-mm-dd'),950,NULL,30);
INSERT INTO emp VALUES (7902,'FORD','ANALYST',7566,to_date('1981-12-3','yyyy-mm-dd'),3000,NULL,20);
INSERT INTO emp VALUES (7934,'MILLER','CLERK',7782,to_date('1982-1-23','yyyy-mm-dd'),1300,NULL,10);8.3 执行SQL，查看默认执行计划
testdb=# explain analyze select * from emp a,dept b where a.deptno=b.deptno;
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------
Hash Join (cost=19.23..35.67 rows=510 width=300) (actual time=0.088..0.098 rows=14 loops=1)
Hash Cond: (a.deptno = b.deptno)
-> Seq Scan on emp a (cost=0.00..15.10 rows=510 width=130) (actual time=0.012..0.015 rows=14
loops=1)
-> Hash (cost=14.10..14.10 rows=410 width=170) (actual time=0.016..0.017 rows=4 loops=1)
Buckets: 1024 Batches: 1 Memory Usage: 9kB
-> Seq Scan on dept b (cost=0.00..14.10 rows=410 width=170) (actual time=0.009..0.009
rows=4 loops=1)
Planning Time: 1.149 ms
Execution Time: 0.182 ms
(8 rows)以上输出可以看到，默认的执行计划走HJ
8.4 模拟NL
testdb=# explain analyze select /*+ nestloop(a b)*/* from emp a,dept b where a.deptno=b.deptno;
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------
Nested Loop (cost=0.15..147.14 rows=510 width=300) (actual time=0.040..0.056 rows=14 loops=1)
-> Seq Scan on emp a (cost=0.00..15.10 rows=510 width=130) (actual time=0.009..0.011 rows=14
loops=1)
-> Index Scan using dept_pkey on dept b (cost=0.15..0.26 rows=1 width=170) (actual time=0.00
2..0.002 rows=1 loops=14)
Index Cond: (deptno = a.deptno)
Planning Time: 0.166 ms
Execution Time: 0.113 ms
(6 rows)8.5 模拟MJ
testdb=# explain analyze select /*+ mergejoin(a b)*/* from emp a,dept b where a.deptno=b.deptno;
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------
Merge Join (cost=69.93..79.63 rows=510 width=300) (actual time=0.168..0.178 rows=14 loops=1)
Merge Cond: (a.deptno = b.deptno)
-> Sort (cost=38.04..39.31 rows=510 width=130) (actual time=0.142..0.146 rows=14 loops=1)
Sort Key: a.deptno
Sort Method: quicksort Memory: 26kB
-> Seq Scan on emp a (cost=0.00..15.10 rows=510 width=130) (actual time=0.014..0.019 r
ows=14 loops=1)
-> Sort (cost=31.89..32.92 rows=410 width=170) (actual time=0.020..0.020 rows=3 loops=1)
Sort Key: b.deptno
Sort Method: quicksort Memory: 25kB
-> Seq Scan on dept b (cost=0.00..14.10 rows=410 width=170) (actual time=0.010..0.011
rows=4 loops=1)
Planning Time: 1.826 ms
Execution Time: 0.417 ms
(12 rows)