On Wed, Apr 24, 2024 at 7:45 AM David G. Johnston < david.g.johns...@gmail.com> wrote:
> On Wed, Apr 24, 2024 at 3:30 AM Peter Eisentraut <pe...@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.
