第17天 | openGauss逻辑结构：索引管理

接着昨天继续学习openGauss,今天是第17天了,还有5天课程就结束了，时间过的真快。今天学习内容是巩固表管理学习内容。
老规矩，先登陆墨天轮为我准备的实训实验室

root@modb:~# su - omm
omm@modb:~$ gsql -r

1.创建表，在表中创建索引

omm=# create table test(id serial primary key,testnum serial);
NOTICE:  CREATE TABLE will create implicit sequence "test_id_seq" for serial column "test.id"
NOTICE:  CREATE TABLE will create implicit sequence "test_testnum_seq" for serial column "test.testnum"
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "test_pkey" for table "test"
CREATE TABLE
omm=# create index idx_test_testnum on test(testnum);
omm=# CREATE INDEX

– 查看创建的索引

omm=# \dt
                        List of relations
 Schema | Name | Type  | Owner |             Storage              
--------+------+-------+-------+----------------------------------
 public | test | table | omm   | {orientation=row,compression=no}
(1 row)

2.通过hint使用索引

–测试准备，创建表customer，并插入数据

omm=# CREATE TABLE customer
omm-# (
omm(# ca_address_sk integer NOT NULL ,
omm(# ca_address_id character(16),
omm(# ca_street_number character(10) ,
omm(# ca_street_name character varying(60) ,
omm(# ca_street_type character(15) ,
omm(# ca_suite_number character(10) ,
omm(# ca_city character varying(60) ,
omm(# ca_county character varying(30) ,
omm(# ca_state character(2) ,
omm(# ca_zip character(10) ,
omm(# ca_country character varying(20) ,
omm(# ca_gmt_offset numeric(5,2) ,
omm(# ca_location_type character(20)
omm(# );
CREATE TABLE

插入数据

insert into customer 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');

创建索引

omm=# create index customer_idx on  customer(ca_address_sk);
CREATE INDEX

–通过hint强制使用索引，查看执行计划

omm=# EXPLAIN SELECT /*+ indexscan(customer customer_idx ) */ 
omm-#  * FROM customer WHERE ca_address_sk<100;
                                  QUERY PLAN                                   
-------------------------------------------------------------------------------
 [Bypass]
 Index Scan using customer_idx on customer  (cost=0.00..8.27 rows=1 width=788)
   Index Cond: (ca_address_sk < 100)
(3 rows)

3.rename索引

omm=# ALTER INDEX idx_test_testnum RENAME TO idx_test_testnum_new;
ALTER INDEX

4.重建索引

–重建一个单独索引

omm=# ALTER INDEX  idx_test_testnum_new REBUILD;
REINDEX
omm=# REINDEX INDEX  idx_test_testnum_new;
REINDEX

–重建所有索引

omm=# reindex table test;
REINDEX

5.移动索引到其他表空间

–创建表空间myindex_ts：

omm=#  CREATE TABLESPACE myindex_ts RELATIVE LOCATION 'tablespace/myindex_ts1';
CREATE TABLESPACE

–将索引idx_test_testnum_new移动到表空间myindex_ts：

omm=# ALTER INDEX idx_test_testnum_new SET TABLESPACE myindex_ts;
omm=# ALTER INDEX

–查看索引所在的表空间

omm=#  select * from pg_indexes where tablename = 'test';
 schemaname | tablename |      indexname       | tablespace |                                       indexdef                      
                  
------------+-----------+----------------------+------------+---------------------------------------------------------------------
------------------
 public     | test      | test_pkey            |            | CREATE UNIQUE INDEX test_pkey ON test USING btree (id) TABLESPACE pg
_default
 public     | test      | idx_test_testnum_new | myindex_ts | CREATE INDEX idx_test_testnum_new ON test USING btree (testnum) TABL
ESPACE myindex_ts
(2 rows)

6.删除索引

omm=# drop index idx_test_testnum_new;
omm=# DROP INDEX