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Re: doc: create table improvements - Mailing list pgsql-hackers

From David G. Johnston
Subject Re: doc: create table improvements
Date
Msg-id CAKFQuwZVH=Yn5t+YDX9i4X0HCVbPXbLu0A-KOp-3jY6=vZCtsw@mail.gmail.com
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In response to Re: doc: create table improvements  ("David G. Johnston" <david.g.johnston@gmail.com>)
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On Wed, Apr 24, 2024 at 7:45 AM David G. Johnston <david.g.johnston@gmail.com> wrote:
On Wed, Apr 24, 2024 at 3:30 AM Peter Eisentraut <peter@eisentraut.org> wrote:
 > +   The reliability characteristics of a table are governed by its
 > +   persistence mode.  The default mode is described
 > +   <link linkend="wal-reliability">here</link>
 > +   There are two alternative modes that can be specified during
 > +   table creation:
 > +   <link linkend="sql-createtable-temporary">temporary</link> and
 > +   <link linkend="sql-createtable-unlogged">unlogged</link>.

Not sure reliability is the best word here.  I mean, a temporary table
isn't any less reliable than any other table.  It just does different
things.


Given the name of the section where this is all discussed I'm having trouble going with a different word.  But better framing and phrasing I can do:

A table may be opted out of certain storage aspects of reliability, as described [here], by specifying either of the alternate persistence modes: [temporary] or [logged]. The specific trade-offs and implications are detailed below.


Or maybe:

A table operates in one of three persistence modes (default, [temporary], and [unlogged]) described in [Chapter 28]. --point to the intro page for the chapter as expanded as below, not the reliability page.

diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml
index 05e2a8f8be..102cfeca68 100644
--- a/doc/src/sgml/wal.sgml
+++ b/doc/src/sgml/wal.sgml
@@ -5,8 +5,17 @@

  <para>
   This chapter explains how to control the reliability of
-  <productname>PostgreSQL</productname>, including details about the
-  Write-Ahead Log.
+  <productname>PostgreSQL</productname>.  At its core this
+  involves writing all changes to disk twice - first to a
+  journal of changes called the write-ahead-log (WAL) and
+  then to the physical pages that comprise permanent tables
+  on disk (heap).  This results in four high-level
+  <term>persistence modes</term> for tables.
+  The default mode results in both these features being
+  enabled.  Temporary tables forgo both of these options,
+  while unlogged tables only forgo WAL.  There is no WAL-only
+  operating mode.  The rest of this chapter discusses
+  implementation details related to these two options.
  </para>

David J.

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