1.准备数据
--使用gsql登录openGauss
root@modb:~# su - omm
omm@modb:~$ gsql -r
gsql ((openGauss 2.0.0 build 78689da9) compiled at 2021-03-31 21:03:52 commit 0 last mr )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.
omm=#
--创建用户
omm=# Create schema tpcds;
CREATE SCHEMA
--创建表
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)
);
CREATE TABLE
--插入测试数据
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');
INSERT 0 3
--使用序列的generate_series(1,N)函数对表插入数据
omm=# insert into tpcds.customer_address values(generate_series(10, 10000));
INSERT 0 9991
2.收集统计信息
--查看系统表中表的统计信息
omm=# select relname, relpages, reltuples from pg_class where relname = 'customer_address';
relname | relpages | reltuples
------------------+----------+-----------
customer_address | 0 | 0
(1 row)
--使用ANALYZE VERBOSE语句更新统计信息，并输出表的相关信息
omm=# analyze VERBOSE tpcds.customer_address;
INFO: analyzing "tpcds.customer_address"(gaussdb pid=1)
INFO: ANALYZE INFO : "customer_address": scanned 55 of 55 pages, containing 9994 live rows and 0 dead rows; 9994 rows in sample, 9994 estimated total rows(gaussdb pid=1)
ANALYZE
--查看系统表中表的统计信息
omm=# select relname, relpages, reltuples from pg_class where relname = 'customer_address';
relname | relpages | reltuples
------------------+----------+-----------
customer_address | 55 | 9994
(1 row)
3.打印执行计划
--使用默认的打印格式
omm=# SET explain_perf_mode=normal;
SET
--显示表简单查询的执行计划
omm=# EXPLAIN SELECT * FROM tpcds.customer_address;
QUERY PLAN
-----------------------------------------------------------------------
Seq Scan on customer_address (cost=0.00..154.94 rows=9994 width=151)
(1 row)
--以JSON格式输出的执行计划（explain_perf_mode为normal时）
omm=# EXPLAIN(FORMAT JSON) SELECT * FROM tpcds.customer_address;
QUERY PLAN
--------------------------------------------
[ +
{ +
"Plan": { +
"Node Type": "Seq Scan", +
"Relation Name": "customer_address",+
"Alias": "customer_address", +
"Startup Cost": 0.00, +
"Total Cost": 154.94, +
"Plan Rows": 9994, +
"Plan Width": 151 +
} +
} +
]
(1 row)
--禁止开销估计的执行计划
omm=# EXPLAIN(COSTS FALSE)SELECT * FROM tpcds.customer_address;
QUERY PLAN
------------------------------
Seq Scan on customer_address
(1 row)
--带有聚集函数查询的执行计划
omm=# EXPLAIN SELECT SUM(ca_address_sk) FROM tpcds.customer_address WHERE ca_address_sk<100;
QUERY PLAN
-------------------------------------------------------------------------
Aggregate (cost=180.16..180.17 rows=1 width=12)
-> Seq Scan on customer_address (cost=0.00..179.93 rows=94 width=4)
Filter: (ca_address_sk < 100)
(3 rows)
--有索引条件的执行计划
omm=# create index customer_address_idx on tpcds.customer_address(ca_address_sk);
CREATE INDEX
omm=# EXPLAIN SELECT * FROM tpcds.customer_address WHERE ca_address_sk<100;
QUERY PLAN
------------------------------------------------------------------------------------------------
[Bypass]
Index Scan using customer_address_idx on customer_address (cost=0.00..9.90 rows=94 width=151)
Index Cond: (ca_address_sk < 100)
(3 rows)
4.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
omm=# update tpcds.customer_address set ca_address_sk = ca_address_sk + 1 where ca_address_sk <100;
UPDATE 93
omm=# VACUUM (VERBOSE, ANALYZE) tpcds.customer_address;
INFO: vacuuming "tpcds.customer_address"(gaussdb pid=1)
INFO: index "customer_address_idx" now contains 10087 row versions in 31 pages(gaussdb pid=1)
DETAIL: 0 index row versions were removed.
0 index pages have been deleted, 0 are currently reusable.
CPU 0.00s/0.00u sec elapsed 0.00 sec.
INFO: "customer_address": found 0 removable, 10087 nonremovable row versions in 55 out of 55 pages(gaussdb pid=1)
DETAIL: 93 dead row versions cannot be removed yet.
There were 0 unused item pointers.
0 pages are entirely empty.
CPU 0.00s/0.00u sec elapsed 0.00 sec.
INFO: analyzing "tpcds.customer_address"(gaussdb pid=1)
INFO: ANALYZE INFO : "customer_address": scanned 55 of 55 pages, containing 9994 live rows and 93 dead rows; 9994 rows in sample, 9994 estimated total rows(gaussdb pid=1)
VACUUM
5.事务日志检查点
--检查点?-HECKPOINT）是一个事务日志中的点，所有数据文件都在该点被更新以反映日志中的信息，所有数据文件都将被刷新到磁盘
omm=# CHECKPOINT;
CHECKPOINT
6.清理数据
omm=# drop schema tpcds cascade;
NOTICE: drop cascades to table tpcds.customer_address
DROP SCHEMA
练习：
1.创建分区表，并用generate_series(1,N)函数对表插入数据
omm=# create schema junzi;
CREATE SCHEMA
omm=# CREATE TABLE junzi.products
(
CA_ADDRESS_SK INTEGER NOT NULL,
CA_ADDRESS_ID CHAR(16) NULL,
CA_STREET_NUMBER CHAR(10) ,
CA_STREET_NAME VARCHAR(60) ,
CA_STREET_TYPE CHAR(15) ,
CA_SUITE_NUMBER CHAR(10) ,
CA_CITY VARCHAR(60) ,
CA_COUNTY VARCHAR(30) ,
CA_STATE CHAR(2) ,
CA_ZIP CHAR(10) ,
CA_COUNTRY VARCHAR(20) ,
CA_GMT_OFFSET DECIMAL(5,2) ,
CA_LOCATION_TYPE CHAR(20)
)
PARTITION BY RANGE(CA_ADDRESS_SK)
(
PARTITION p1 VALUES LESS THAN (3000),
PARTITION p2 VALUES LESS THAN (5000),
PARTITION p3 VALUES LESS THAN (MAXVALUE)
);
CREATE TABLE
insert into junzi.products 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');
INSERT 0 3
insert into junzi.products values(generate_series(10, 10000));
2.收集表统计信息
--查看系统表中表的统计信息
omm=# select relname, relpages, reltuples from pg_class where relname = 'customer_address';
relname | relpages | reltuples
---------+----------+-----------
(0 rows)
--使用ANALYZE VERBOSE语句更新统计信息，并输出表的相关信息
omm=# analyze VERBOSE junzi.products;
INFO: analyzing "junzi.products"(gaussdb pid=1)
INFO: ANALYZE INFO : "products": scanned 17 of 17 pages, containing 2993 live rows and 0 dead rows; 2993 rows in sample, 2993 estimated total rows(gaussdb pid=1)
INFO: ANALYZE INFO : "products": scanned 11 of 11 pages, containing 2000 live rows and 0 dead rows; 2000 rows in sample, 2000 estimated total rows(gaussdb pid=1)
INFO: ANALYZE INFO : "products": scanned 28 of 28 pages, containing 5001 live rows and 0 dead rows; 5001 rows in sample, 5001 estimated total rows(gaussdb pid=1)
ANALYZE
--查看系统表中表的统计信息
omm=# select relname, relpages, reltuples from pg_class where relname = 'customer_address';
relname | relpages | reltuples
---------+----------+-----------
(0 rows)
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
omm=# EXPLAIN SELECT * FROM junzi.products;
-> Partitioned Seq Scan on products (cost=0.00..155.94 rows=9994 width=151)
Selected Partitions: 1..3
(4 rows)
omm=# QUERY PLAN
---------------------------------------------------------------------------------
Partition Iterator (cost=0.00..155.94 rows=9994 width=151)
Iterations: 3
omm=# CREATE INDEX products_index1 ON junzi.products(CA_ADDRESS_SK);
CREATE INDEX
omm=# EXPLAIN SELECT * FROM junzi.products WHERE ca_address_sk<100;
QUERY PLAN
-----------------------------------------------------------------------------------
Index Scan using products_index1 on products (cost=0.00..9.90 rows=94 width=151)
Index Cond: (ca_address_sk < 100)
(2 rows)
4.更新表数据，并做垃圾收集
omm=# update junzi.products set ca_address_sk = ca_address_sk + 1 where ca_address_sk <100;
UPDATE 93
omm=# VACUUM (VERBOSE, ANALYZE) junzi.products;
INFO: vacuuming "junzi.products"(gaussdb pid=1)
INFO: index "products_index1" now contains 3086 row versions in 31 pages(gaussdb pid=1)
DETAIL: 0 index row versions were removed.
0 index pages have been deleted, 0 are currently reusable.
CPU 0.00s/0.00u sec elapsed 0.00 sec.
INFO: "products": found 0 removable, 3086 nonremovable row versions in 17 out of 17 pages(gaussdb pid=1)
DETAIL: 93 dead row versions cannot be removed yet.
There were 0 unused item pointers.
0 pages are entirely empty.
CPU 0.00s/0.00u sec elapsed 0.00 sec.
INFO: vacuuming "junzi.products"(gaussdb pid=1)
INFO: index "products_index1" now contains 2000 row versions in 31 pages(gaussdb pid=1)
DETAIL: 0 index row versions were removed.
0 index pages have been deleted, 0 are currently reusable.
CPU 0.00s/0.00u sec elapsed 0.00 sec.
INFO: "products": found 0 removable, 2000 nonremovable row versions in 11 out of 11 pages(gaussdb pid=1)
DETAIL: 0 dead row versions cannot be removed yet.
There were 0 unused item pointers.
0 pages are entirely empty.
CPU 0.00s/0.00u sec elapsed 0.00 sec.
INFO: vacuuming "junzi.products"(gaussdb pid=1)
INFO: index "products_index1" now contains 5001 row versions in 31 pages(gaussdb pid=1)
DETAIL: 0 index row versions were removed.
0 index pages have been deleted, 0 are currently reusable.
CPU 0.00s/0.00u sec elapsed 0.00 sec.
INFO: "products": found 0 removable, 5001 nonremovable row versions in 28 out of 28 pages(gaussdb pid=1)
DETAIL: 0 dead row versions cannot be removed yet.
There were 0 unused item pointers.
0 pages are entirely empty.
CPU 0.00s/0.00u sec elapsed 0.00 sec.
INFO: scanned index "products_index1" to remove 0.000000 invisible rows(gaussdb pid=1)
DETAIL: CPU 0.00s/0.00u sec elapsed 0.00 sec.
INFO: analyzing "junzi.products"(gaussdb pid=1)
INFO: ANALYZE INFO : "products": scanned 17 of 17 pages, containing 2993 live rows and 93 dead rows; 2993 rows in sample, 2993 estimated total rows(gaussdb pid=1)
INFO: ANALYZE INFO : "products": scanned 11 of 11 pages, containing 2000 live rows and 0 dead rows; 2000 rows in sample, 2000 estimated total rows(gaussdb pid=1)
INFO: ANALYZE INFO : "products": scanned 28 of 28 pages, containing 5001 live rows and 0 dead rows; 5001 rows in sample, 5001 estimated total rows(gaussdb pid=1)
VACUUM
5.清理数据
omm=# drop schema junzi;
ERROR: cannot drop schema junzi because other objects depend on it
DETAIL: table junzi.products depends on schema junzi
HINT: Use DROP ... CASCADE to drop the dependent objects too.
omm=# drop schema junzi cascade;
NOTICE: drop cascades to table junzi.products
DROP SCHEMA
最后修改时间：2021-12-20 00:10:50
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