From 6654bb92047b37cee053cedd6fa1829841b2ad8e Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 28 Aug 2024 07:26:48 +0200
Subject: Add prefetching support on macOS

macOS doesn't have posix_fadvise(), but fcntl() with the F_RDADVISE
command does the same thing.

Some related documentation has been generalized to not mention
posix_advise() specifically anymore.

Reviewed-by: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/0827edec-1317-4917-a186-035eb1e3241d%40eisentraut.org
---
 doc/src/sgml/config.sgml | 14 +++++---------
 doc/src/sgml/wal.sgml    |  4 ++--
 2 files changed, 7 insertions(+), 11 deletions(-)

(limited to 'doc/src')

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 2937384b001..12feac60874 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -2679,11 +2679,9 @@ include_dir 'conf.d'
         </para>
 
         <para>
-         Asynchronous I/O depends on an effective <function>posix_fadvise</function>
-         function, which some operating systems lack.  If the function is not
-         present then setting this parameter to anything but zero will result
-         in an error.  On some operating systems (e.g., Solaris), the function
-         is present but does not actually do anything.
+         Asynchronous I/O requires that the operating system supports issuing
+         read-ahead advice.  If there is no operating system support then
+         setting this parameter to anything but zero will result in an error.
         </para>
 
         <para>
@@ -3852,10 +3850,8 @@ include_dir 'conf.d'
         <literal>off</literal>, <literal>on</literal> and
         <literal>try</literal> (the default).  The setting
         <literal>try</literal> enables
-        prefetching only if the operating system provides the
-        <function>posix_fadvise</function> function, which is currently used
-        to implement prefetching.  Note that some operating systems provide the
-        function, but it doesn't do anything.
+        prefetching only if the operating system provides support for issuing
+        read-ahead advice.
        </para>
        <para>
         Prefetching blocks that will soon be needed can reduce I/O wait times
diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml
index d5df65bc693..0ba0c930b78 100644
--- a/doc/src/sgml/wal.sgml
+++ b/doc/src/sgml/wal.sgml
@@ -841,8 +841,8 @@
    The <xref linkend="guc-maintenance-io-concurrency"/> and
    <xref linkend="guc-wal-decode-buffer-size"/> settings limit prefetching
    concurrency and distance, respectively.  By default, it is set to
-   <literal>try</literal>, which enables the feature on systems where
-   <function>posix_fadvise</function> is available.
+   <literal>try</literal>, which enables the feature on systems that support
+   issuing read-ahead advice.
   </para>
  </sect1>
 
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