Aug 03, 2016 In this post, I am creating an auto increment PRIMARY KEY using a custom sequence of the PostgreSQL. PostgreSQL already provides two data types for auto increment id, serial (4 bytes) & bigserial (8 bytes). 4 options to generate primary keys. The JPA specification supports 4 different primary key generation strategies which generate the primary key values programmatically or use database features, like auto-incremented columns or sequences. May 23, 2015 In order to gain the benefits of using UUID primary keys with lower keyspace fragmentation perhaps Drew points out that it is better to use uuidgeneratev1mc from the uuid-ossp extension because underneath it is using a time based seq algorithm which you can read about in the postgresql documentation.
PostgreSQL has the data types smallserial, serial and bigserial; these are not true types, but merely a notational convenience for creating unique identifier columns. These are similar to AUTO_INCREMENT property supported by some other databases.
If you wish a serial column to have a unique constraint or be a primary key, it must now be specified, just like any other data type.
The type name serial creates an integer columns. The type name bigserial creates a bigint column. bigserial should be used if you anticipate the use of more than 231 identifiers over the lifetime of the table. The type name smallserial creates a smallint column.
Syntax
The basic usage of SERIAL dataype is as follows −
Example
Consider the COMPANY table to be created as follows −
Now, insert the following records into table COMPANY −
This will insert seven tuples into the table COMPANY and COMPANY will have the following records −
Summary: in this tutorial, you will learn about the PostgreSQL
SERIAL pseudo-type and how to use the SERIAL pseudo-type to define auto-increment columns in tables.
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Introduction to the PostgreSQL
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