Skip to content

Latest commit

 

History

History
48 lines (34 loc) · 2.55 KB

tutorial.md

File metadata and controls

48 lines (34 loc) · 2.55 KB
Raw

Tutorial to remember stuff

Control File

A control file in PostgreSQL is a key component of an extension. It provides essential metadata about the extension to the PostgreSQL server. The control file is named after the extension with the suffix .control and must be placed in the PostgreSQL extension directory.

Purpose of Control File:

The control file is used to:

  • Identify the Extension: It provides the name of the extension and other key details.
  • Manage Versions: It specifies the version of the extension and supports versioning for extension updates.
  • Dependency Management: It can specify dependencies on other extensions or PostgreSQL modules.
  • Configuration: It includes configuration parameters like the default superuser privileges for the extension.

Contents of Control File:

Typically, a control file includes:

  • Extension Name: The name of the extension.
  • Default Version: The current version of the extension.
  • Comment: A brief description of what the extension does.
  • Schema: Optional. Specifies the default schema for the objects created by the extension.
  • Dependencies: Optional. Lists other extensions that this extension depends on.
  • Module Pathname: The name of the shared library (without the platform-specific prefix and suffix) for the extension.
  • Requisite Files: The SQL script files needed to install the extension (and optionally to update it from previous versions).

Example

Let's consider an example control file called myextension.control for a fictional extension named myextension:

comment = 'My custom PostgreSQL extension'
default_version = '1.0'
module_pathname = '$libdir/myextension'
relocatable = false
schema = 'public'
requires = 'other_extension'

In this example:

  • comment: Describes the extension.
  • default_version: Specifies the version of the extension, which should match a corresponding SQL file (e.g., myextension--1.0.sql for installation scripts).
  • module_pathname: The location of the compiled binary code for the extension. $libdir is a placeholder for PostgreSQL's library directory.
  • relocatable: Indicates whether the extension can be installed in a schema different from the one specified. false means it's not relocatable.
  • schema: The default schema where the extension will be installed.
  • requires: Specifies any other extensions that are needed for this extension to work.

In summary, the control file is vital for defining the properties and dependencies of a PostgreSQL extension, and it informs PostgreSQL about how to handle the extension during installation and updates.