PostgreSQL Programmer's Guide
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# Documentation Sources

Documentation sources include plain text files, man pages, and html. However, most new Postgres documentation will be written using the Standard Generalized Markup Language (SGML) DocBook Document Type Definition (DTD). Much of the existing documentation has been or will be converted to SGML.

The purpose of SGML is to allow an author to specify the structure and content of a document (e.g. using the DocBook DTD), and to have the document style define how that content is rendered into a final form (e.g. using Norm Walsh's stylesheets).

Documentation has accumulated from several sources. As we integrate and assimilate existing documentation into a coherent documentation set, the older versions will become obsolete and will be removed from the distribution. However, this will not happen immediately, and will not happen to all documents at the same time. To ease the transition, and to help guide developers and writers, we have defined a transition roadmap.

## Document Structure

There are currently five separate documents written in DocBook. Each document has a container source document which defines the DocBook environment and other document source files. These primary source files are located in `doc/src/sgml/`, along with many of the other source files used for the documentation. The primary source files are:

postgres.sgml

  This is the integrated document, including all other documents as parts. Output is generated in HTML since the browser interface makes it easy to move around all of the documentation by just clicking. The other documents are available in both HTML and hardcopy.

tutorial.sgml

  The introductory tutorial, with examples. Does not include programming topics, and is intended to help a reader unfamiliar with SQL. This is the "getting started" document.

user.sgml

  The User's Guide. Includes information on data types and user-level interfaces. This is the place to put information on "why".

reference.sgml

  The Reference Manual. Includes Postgres SQL syntax. This is the place to put information on "how".

programming.sgml

  The Programmer's Guide. Includes information on Postgres extensibility and on the programming interfaces.

admin.sgml

  The Administrator's Guide. Include installation and release notes.

## Styles and Conventions

DocBook has a rich set of tags and constructs, and a suprisingly large percentage are directly and obviously useful for well-formed documentation. The Postgres documentation set has only recently been adapted to SGML, and in the near future several sections of the set will be selected and maintained as prototypical examples of DocBook usage. Also, a short summary of DocBook tags will be included below.

## SGML Authoring Tools

The current Postgres documentation set was written using a plain text editor (or emacs/psgml; see below) with the content marked up using SGML DocBook tags.

SGML and DocBook do not suffer from an oversupply of open-source authoring tools. The most common toolset is the emacs/xemacs editing package with the psgml feature extension. On some systems (e.g. RedHat Linux) these tools are provided in a typical full installation.

### emacs/psgml

emacs (and xemacs) have an SGML major mode. When properly configured, this will allow you to use emacs to insert tags and check markup consistancy.

Put the following in your `~/.emacs` environment file (adjusting the path names to be appropriate for your system):

    ; ********** for SGML mode (psgml)

    (setq sgml-catalog-files "/usr/lib/sgml/CATALOG")
    (setq sgml-local-catalogs "/usr/lib/sgml/CATALOG")

    (autoload 'sgml-mode "psgml" "Major mode to edit SGML files." t )

and add an entry in the same file for SGML into the (existing) definition for auto-mode-alist:

    (setq
      auto-mode-alist
      '(("\\.sgml$" . sgml-mode)
       ))

Each SGML source file has the following block at the end of the file:

    !-- Keep this comment at the end of the file
    Local variables:
    mode: sgml
    sgml-omittag:t
    sgml-shorttag:t
    sgml-minimize-attributes:nil
    sgml-always-quote-attributes:t
    sgml-indent-step:1
    sgml-indent-data:t
    sgml-parent-document:nil
    sgml-default-dtd-file:"./reference.ced"
    sgml-exposed-tags:nil
    sgml-local-catalogs:("/usr/lib/sgml/catalog")
    sgml-local-ecat-files:nil
    End:
    --

The Postgres distribution includes a parsed DTD definitions file `reference.ced`. You may find that

When using emacs/psgml, a comfortable way of working with these separate files of book parts is to insert a proper DOCTYPE declaration while you're editing them. If you are working on this source, for instance, it's an appendix chapter, so you would specify the document as an "appendix" instance of a DocBook document by making the first line look like this:

          !doctype appendix PUBLIC "-//Davenport//DTD DocBook V3.0//EN"

This means that anything and everything that reads SGML will get it right, and I can verify the document with "nsgmls -s docguide.sgml".

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