Exploring the Different Types of Tables in Oracle: A Comprehensive Overview（oracle表的种类）

Introduction

When talking about database management systems, Oracle is regarded as one of the most popular database systems. It comes with a variety of database objects such as tables, views, indexes and so on. Tables are the most commonly used database objects to store and retrieve data. In this article, we will provide a comprehensive overview of the different types of tables used in Oracle.

Types of Tables

There are various types of tables available in Oracle. The types of tables available are:

1. Heap Tables

2. Cluster Tables

3. Index Organized Tables

4. External Tables

5. Partitioned Tables

Heap Tables

Heap tables are most commonly used database objects in Oracle. They are comprised of an allocated space for data storage, which is in a rough format with no sorting pattern. Data is randomly extracted from these tables based on its particular value. It is quite flexible as no strict index is present and is easy to copy and move data from one database to another.

Cluster Tables

Cluster tables are used to store data that is commonly accessed together. These tables are particularly useful where data has some kind of relationship between them. A cluster table consists of a group of rows with similar values. The values that they have in common are known as the cluster key.

Index Organized Tables

An Index-Organized Table (IOT) is an Oracle database object in which the table data is stored in an ordered fashion based on the index key column values. This type of table is particularly useful for queries which require sorting the data. The index key columns are used to organize the rows and the table can be queried using the ordered index key columns.

External Tables

External tables are database objects that are used to access data stored outside of the Oracle database. This data can be stored in flat files (e.g. comma separated values) or in external databases. The data stored in the external tables can be queried and manipulated just like normal database tables.

Partitioned Tables

Partitioned tables are database objects used to split a single table into multiple pieces. A partitioned table consists of multiple “sub” tables, where each sub table is referred to as a ‘partition’. Each partition is stored as a separate table, but they all together comprise of a single table. This type of table is particularly useful in scenarios where data needs to be queried and manipulated very quickly, as the data can be queried and manipulated based on the partition key.

Conclusion

In conclusion, we have discussed the different types of tables available in Oracle. Heap tables are the most commonly used type of table, however, there are other types available such as Cluster tables, Index-Organized tables, External tables and Partitioned tables. Each type of table has its own advantages and drawbacks and can be used depending on the specific requirements of a database.