GBase 8c boasts powerful and rich plugin features, including support for the Dolphin Extension Reference. This extension enhances MySQL compatibility (dbcompatibility='B', referred to as B compatibility database hereafter) in GBase 8c, covering keywords, data types, constants and macros, functions and operators, expressions, type conversions, DDL/DML/DCL syntax, stored procedures/custom functions, system views, and more.

The Dolphin plugin inherits the original SQL syntax of the kernel. This article briefly introduces the new/modified content for the kernel syntax.

Installation and Usage Restrictions

Using Dolphin

The plugin is automatically installed and loaded, requiring no manual installation.

Install GBase 8c.
Create a B database and connect to it using the initial user. The Dolphin plugin is enabled by default.

CREATE DATABASE dbname WITH DBCOMPATIBILITY='B';
\q
$ gsql -d dbname -p 15400 -U gbase

Dolphin Usage Restrictions

The Dolphin plugin is not supported in the mini version.
The Dolphin plugin cannot be deleted.
The Dolphin plugin can only be created in a B compatibility database.
The Dolphin plugin needs to create data types, functions, etc., under schemas like pg_catalog. Therefore, loading the Dolphin plugin requires initial user privileges. GBase 8c automatically loads the Dolphin plugin the first time the initial user or a user with initial user privileges connects to the B database. If a B compatibility database has never been connected to by the initial user or a user with initial user privileges, the Dolphin plugin will not be loaded.
All new/modified syntax in Dolphin cannot be viewed through the \h help command in the gsql client, nor does it support auto-completion in the gsql client.
Creating the Dolphin plugin will delete any existing same-named functions and types required by the plugin and any dependent objects that existed previously.
The Dolphin plugin depends on the public schema, so it does not support deleting the public schema using the drop schema method.
When connecting to a B compatibility database with the Dolphin plugin installed, the GUC parameter behavior_compat_options will be modified by default, adding display_leading_zero and select_into_return_null options to maintain compatibility.

Keyword Syntax Introduction

SQL has reserved and non-reserved words. According to standards, reserved words must not be used as other identifiers. Non-reserved words have special meanings in specific contexts but can be used as identifiers in other contexts. Identifiers must follow these naming conventions:

Identifiers must be letters, underscores, digits (0-9), or dollar signs ($).
Identifiers must begin with a letter (a-z) or an underscore (_).

Notes

These naming conventions are recommended but not mandatory.

In special cases, double quotes or backticks (`) can be used to avoid errors caused by special characters.

Compared to native GBase 8c syntax, Dolphin introduces the following keyword modifications:

Added MEDIUMINT as a non-reserved keyword.
The keyword DATE can be used as a function.
Added LAST_DAY as a reserved keyword to distinguish between the original GBase 8c LAST_DAY function and the Dolphin LAST_DAY function at the syntax level.
Added GET_FORMAT as a non-reserved keyword for syntax recognition of the GET_FORMAT function.
Added DAY_HOUR, DAY_MINUTE, DAY_SECOND, DAY_MICROSECOND, HOUR_MINUTE, HOUR_SECOND, HOUR_MICROSECOND, MINUTE_SECOND, MINUTE_MICROSECOND, SECOND_MICROSECOND as non-reserved keywords for the EXTRACT function to recognize corresponding units.
Changed the keyword AUTHID level from RESERVED_KEYWORD to COL_NAME_KEYWORD, allowing it to be used as a table or column name.
Changed the keyword BODY level from UNRESERVED_KEYWORD to RESERVED_KEYWORD.
Added DUAL as a reserved keyword.

Example

Create a table with FIXED(p,s), FIXED, decimal, and number types.

CREATE TABLE dec_type_t1 ( DEC_COL1 FIXED, DEC_COL2 FIXED(20,5), DEC_COL3 DECIMAL, DEC_COL4 NUMBER );

View the table structure.

sql \d dec_type_t1

The result will be:

These examples and notes illustrate the powerful features and compatibility improvements brought by the Dolphin plugin in GBase 8c.

Overview of GBase 8c B Compatibility Database