学习目标
学习openGauss收集统计信息、打印执行计划、垃圾收集和checkpoint
连接数据库
#第一次进入等待15秒
#数据库启动中...
su - omm
gsql -r
课后作业
1.创建分区表，并用generate_series(1,N)函数对表插入数据
1.1、创建分区表
--创建表
Create schema tpcds;
CREATE TABLE tpcds.customer_address
(
ca_address_sk integer NOT NULL ,
ca_address_id character(16),
ca_street_number character(10) ,
ca_street_name character varying(60) ,
ca_street_type character(15) ,
ca_suite_number character(10) ,
ca_city character varying(60) ,
ca_county character varying(30) ,
ca_state character(2) ,
ca_zip character(10) ,
ca_country character varying(20) ,
ca_gmt_offset numeric(5,2) ,
ca_location_type character(20)
);
--插入数据
insert into tpcds.customer_address values
(1, 'AAAAAAAABAAAAAAA', '18', 'Jackson', 'Parkway', 'Suite 280', 'Fairfield', 'Maricopa County', 'AZ', '86192' ,'United States', -7.00, 'condo'),
(2, 'AAAAAAAACAAAAAAA', '362', 'Washington 6th', 'RD', 'Suite 80', 'Fairview', 'Taos County', 'NM', '85709', 'United States', -7.00, 'condo'),
(3, 'AAAAAAAADAAAAAAA', '585', 'Dogwood Washington', 'Circle', 'Suite Q', 'Pleasant Valley', 'York County', 'PA', '12477', 'United States', -5.00, 'single family');
1.2、用generate_series(1,N)函数对表插入数据
insert into tpcds.customer_address values(generate_series(1, 10000));
2.收集表统计信息
–查看系统表中表的统计信息
select relname, relpages, reltuples from pg_class where relname = 'customer_address';
—使用ANALYZE VERBOSE语句更新统计信息，并输出表的相关信息
analyze VERBOSE tpcds.customer_address;
–查看系统表中表的统计信息
select relname, relpages, reltuples from pg_class where relname = 'customer_address';
3.显示简单查询的执行计划；建立索引并显示有索引条件的执行计划
3.1、显示简单查询的执行计划
–使用默认的打印格式
SET explain_perf_mode=normal;
–显示表简单查询的执行计划
EXPLAIN SELECT * FROM tpcds.customer_address;
3.2、建立索引并显示有索引条件的执行计划
--创建索引
create index customer_address_idx on tpcds.customer_address(ca_address_sk);
--显示执行计划
EXPLAIN SELECT * FROM tpcds.customer_address WHERE ca_address_sk<100;
4.更新表数据，并做垃圾收集
–VACUUM回收表或B-Tree索引中已经删除的行所占据的存储空间
update tpcds.customer_address set ca_address_sk = ca_address_sk + 1 where ca_address_sk <100; VACUUM (VERBOSE, ANALYZE) tpcds.customer_address;
5.清理数据
drop table tpcds.customer_address;
完成
