How to partition Oracle

Oracle is a relational database management system that is very useful in large enterprises and organizations. Partitioning is a way to improve performance and manage data and storage solutions. Oracle allows tables to be partitioned into smaller segments that can be managed independently. In this article, we will explore the working principle, types, creation and management of Oracle partitions.

1. Working principle of partition

Oracle partitioning is to split a table into several areas for storage, and each area can be maintained independently. Each partition can be contained in a table alongside other partitions. A partitioned table looks like an ordinary table physically and logically. However, a partitioned table stores data in multiple physical locations, which means it improves the performance of queries and updates.

Partitioning the table can improve query performance because Oracle can distribute the query to different areas to achieve concurrent processing. Additionally, if the table contains very large amounts of data, partitioning can help reduce disk I/O traffic. The query only needs to scan the relevant partitions and does not need to scan the entire table, which can greatly improve the query speed.

2. Partition types

Oracle has many partition types. The following are the main partition types supported by Oracle.

1. Range Partitioning

Range partitioning partitions a table based on a column of values. Ranges can be done based on numeric or date columns. For example, you can divide the table into months or quarters based on sales dates. The benefit of range partitioning is that it can handle queries and data operations across multiple partitions.

2. Column partitioning

Column partitioning partitions based on the columns in the table. Rows with the same column values ​​will be placed in the same partition. Column partitioning is more flexible than range partitioning. Typically, you use column partitioning to partition tables that are not easily parsable by numbers or date ranges.

3. Hash Partitioning

Hash partitioning distributes table rows into partitions based on hash values. The hash value is generated using a hash function. The benefit of this partition type is that the data can be spread out and evenly distributed among the partitions. This type of partitioning is useful in situations where data access patterns are difficult to predict.

4. Column range partitioning

Column range partitioning is based on two or more column values ​​​​to partition by numerical range. This partition type is very similar to range partitioning. This type of partitioning is useful when greater flexibility and range operations are required.

3. How to create a partition table

In order to store data, you need to create a partition table. The following are the steps to create a partitioned table:

1. Select a table space

Before creating a partitioned table, you need to select a tablespace in which to store the partitioned table. Table space is the basic unit of physical storage.

2. Create table

Use the CREATE TABLE command to create a partitioned table. When creating a table, you must specify the data type, size, column type, partition type, and partition key fields.

3. Specify the partition key

The partition key is composed of a column or columns in the partition table. The partition key must be unique to the table, which means that the partition key cannot appear repeatedly in the table. You can define partition keys using ranges, columns, hashes, or column ranges.

4. Define Partitions

When creating a partitioned table, you need to define partitions. Partition definition is based on partition key and partition type. You can specify multiple partition definitions, each of which can be of a different range or type.

For example, the following command will create a partitioned table based on department, region and sales date:

CREATE TABLE sales_data
(department_id NUMBER,
region_id NUMBER,
sales_date DATE,
sales_amt NUMBER)
PARTITION BY RANGE (sales_date)
(PARTITION saleseast VALUES LESS THAN (TO_DATE('01-01-2016', 'DD-MM-YYYY')),
PARTITION saleswest VALUES LESS THAN (TO_DATE('01-07-2016', 'DD-MM-YYYY')),
PARTITION salescentral VALUES LESS THAN (TO_DATE('01-01-2017', 'DD-MM-YYYY')),
PARTITION salesnorth VALUES LESS THAN (MAXVALUE));

4. How to manage the partitioned table

Manage the partitioned table included in the partition Insert, delete, update and query data in the table. Here are some guidelines for managing partitioned tables:

1. Inserting Data

When inserting data, you need to insert the value of the partition key column. This indicates into which partition Oracle inserted the data.

2. Query data

When querying data, you only need to query the partitions where they are located to speed up the query. Therefore, it is better to specify the partition limit in the query.

3. Update data

When updating data, you only need to update the data in the partition, without updating the entire table. Therefore, it is better to use partition restrictions when updating data.

4. Deleting data

When deleting data, you only need to delete the data in the partition without deleting the entire table. Use the partition limit statement to delete data faster.

Summary

Oracle partitioning is a way to improve query performance and manage data and storage solutions. Available partitioning types include range partitioning, column partitioning, hash partitioning, and column range partitioning. To create a partitioned table, you select a tablespace, create a table and specify the partition key and partition definition. To manage partitioned tables efficiently, you need to use partition limits to insert, delete, update, and query data.

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