# 使用Ustore进行测试
**创建Ustore表**
使用CREATE TABLE语句创建Ustore表。
```
gaussdb=# CREATE TABLE ustore_table(a INT PRIMARY KEY, b CHAR (20)) WITH (STORAGE_TYPE=USTORE);
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "ustore_table_pkey" for table "ustore_table"
CREATE TABLE
gaussdb=# \d+ ustore_table
Table "public.ustore_table"
Column |     Type      | Modifiers | Storage  | Stats target | Description
--------+---------------+-----------+----------+--------------+-------------
a      | integer       | not null  | plain    |              |
b      | character(20) |           | extended |              |
Indexes:
"ustore_table_pkey" PRIMARY KEY, ubtree (a) WITH (storage_type=USTORE) TABLESPACE pg_default
Has OIDs: no
Distribute By: HASH(a)
Location Nodes: ALL DATANODES
Options: orientation=row, storage_type=ustore, compression=no, segment=off
```
**删除Ustore表**
```
gaussdb=# DROP TABLE ustore_table;
 DROP TABLE
```
**为Ustore表创建索引**
Ustore当前仅支持BTree类型的多版本索引。在一些场景中，为了区别于Astore的BTree索引，也会将Ustore表的多版本BTree索引称为UBTree（Ustore BTree，UBTree介绍详见[UBTree](https://support.huaweicloud.com/distributed-devg-v10-gaussdb/gaussdb-12-0537.html)章节）。用户可以参照以下方式使用CREATE INDEX语句为Ustore表的"a"属性创建一个UBTree索引。
Ustore表不指定创建索引类型，默认创建的是UBTree索引。
![](https://support.huaweicloud.com/distributed-devg-v10-gaussdb/public_sys-resources/caution_3.0-zh-cn.png)
UBTree索引分为RCR版本和PCR版本，默认创建RCR版本的UBTree。若在创建索引时with选项指定(index_txntype=pcr)或者指定GUC的index_txntype=pcr，则创建的是PCR版本的UBTree。
```
gaussdb=# CREATE TABLE test(a int);
CREATE TABLE
gaussdb=# CREATE INDEX UB_tree_index ON test(a);
CREATE INDEX
gaussdb=# \d+ test 
Table "public.test"
 Column |  Type   | Modifiers | Storage | Stats target | Description
--------+---------+-----------+---------+--------------+-------------
 a      | integer |           | plain   |              |
Indexes:
    "ub_tree_index" ubtree (a) WITH (storage_type=USTORE) TABLESPACE pg_default
Has OIDs: no
Distribute By: HASH(a)
Location Nodes: ALL DATANODES
Options: orientation=row, compression=no, storage_type=USTORE, segment=off
--删除Ustore表索引。
gaussdb=# DROP TABLE test;
DROP TABLE
```