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help / color / mirror / Atom feedFrom: Justin Pryzby <pryzby@telsasoft.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: What are exactly bootstrap processes, auxiliary processes, standalone backends, normal backends(user sessions)?
Date: Sat, 14 Aug 2021 19:39:08 -0500
Message-ID: <20210815003908.GP10479@telsasoft.com> (raw)
In-Reply-To: <202107171445.v4okkq2xyytm@alvherre.pgsql>
References: <CALj2ACUtWWWLKAU_R3pryw7JvF1kS+EnBZq1XYSVsJ7ehKkRCQ@mail.gmail.com>
<202107171445.v4okkq2xyytm@alvherre.pgsql>
On Sat, Jul 17, 2021 at 10:45:52AM -0400, Alvaro Herrera wrote:
> On 2021-Jul-17, Bharath Rupireddy wrote:
> > On Thu, Jul 15, 2021 at 8:17 PM Justin Pryzby wrote:
> > > It sounds like something that should be in the glossary, which currently refers
> > > to but doesn't define "auxiliary processes".
> >
> > Thanks. I strongly feel that it should be documented somewhere. I will
> > be happy if someone with a clear idea about these various processes
> > does it.
>
> Auxiliary process
I elaborated on your definition and added here.
https://commitfest.postgresql.org/34/3285/
Attachments:
[text/x-diff] 0001-glossary-definitions-for-auxiliary-processes.patch (4.5K, ../20210815003908.GP10479@telsasoft.com/2-0001-glossary-definitions-for-auxiliary-processes.patch)
download | inline diff:
From 9855c0d186251407c868fe0b0d93571541313f55 Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Sat, 14 Aug 2021 18:51:37 -0500
Subject: [PATCH] glossary definitions for auxiliary processes
---
doc/src/sgml/glossary.sgml | 58 ++++++++++++++++++++++++++++++++++----
1 file changed, 53 insertions(+), 5 deletions(-)
diff --git a/doc/src/sgml/glossary.sgml b/doc/src/sgml/glossary.sgml
index 63ff4bbdf0..881d16d6c4 100644
--- a/doc/src/sgml/glossary.sgml
+++ b/doc/src/sgml/glossary.sgml
@@ -123,6 +123,27 @@
</glossdef>
</glossentry>
+ <glossentry id="glossary-auxiliary">
+ <glossterm>Auxiliary process</glossterm>
+ <glossdef>
+ <para>
+ Process that is in charge of a specific, hardcoded, background task for
+ an <glossterm linkend="glossary-instance">instance</glossterm>.
+ The auxiliary processes consist of
+<!-- the autovacuum launcher (but not the autovacuum workers), -->
+ the <glossterm linkend="glossary-background-writer">background writer</glossterm>,
+ the <glossterm linkend="glossary-checkpointer">checkpointer</glossterm>,
+ the <glossterm linkend="glossary-stats-collector">statistics collector</glossterm>,
+ the <glossterm linkend="glossary-logger">logger</glossterm>,
+ the <glossterm linkend="glossary-startup-process">startup process</glossterm>,
+ the <glossterm linkend="glossary-wal-archiver">WAL archiver</glossterm>.
+ the <glossterm linkend="glossary-wal-receiver">WAL receiver</glossterm>
+ (but not the WAL senders), and the
+ <glossterm linkend="glossary-wal-writer">WAL writer</glossterm>.
+ </para>
+ </glossdef>
+ </glossentry>
+
<glossentry id="glossary-backend">
<glossterm>Backend (process)</glossterm>
<glossdef>
@@ -163,7 +184,7 @@
<glossterm>Background writer (process)</glossterm>
<glossdef>
<para>
- A process that writes dirty
+ An auxiliary process that writes dirty
<glossterm linkend="glossary-data-page">data pages</glossterm> from
<glossterm linkend="glossary-shared-memory">shared memory</glossterm> to
the file system. It wakes up periodically, but works only for a short
@@ -285,7 +306,7 @@
<glossterm>Checkpointer (process)</glossterm>
<glossdef>
<para>
- A specialized process responsible for executing checkpoints.
+ An auxiliary process that is responsible for executing checkpoints.
</para>
</glossdef>
</glossentry>
@@ -881,7 +902,7 @@
<glossterm>Logger (process)</glossterm>
<glossdef>
<para>
- If activated, the process
+ An auxiliary process which (if enabled)
writes information about database events into the current
<glossterm linkend="glossary-log-file">log file</glossterm>.
When reaching certain time- or
@@ -1452,6 +1473,16 @@
</glossdef>
</glossentry>
+ <glossentry id="glossary-startup-process">
+ <glossterm>Startup process</glossterm>
+ <glossdef>
+ <para>
+ An auxiliary process that replays WAL during crash recovery and (on
+ replicas) archive recovery.
+ </para>
+ </glossdef>
+ </glossentry>
+
<glossentry id="glossary-sql-object">
<glossterm>SQL object</glossterm>
<glossdef>
@@ -1514,7 +1545,7 @@
<glossterm>Stats collector (process)</glossterm>
<glossdef>
<para>
- This process collects statistical information about the
+ An auxiliary process that collects statistical information about the
<glossterm linkend="glossary-instance">instance</glossterm>'s activities.
</para>
<para>
@@ -1856,7 +1887,8 @@
<glossterm>WAL archiver (process)</glossterm>
<glossdef>
<para>
- A process that saves copies of <glossterm linkend="glossary-wal-file">WAL files</glossterm>
+ An auxiliary process that saves copies of
+ <glossterm linkend="glossary-wal-file">WAL files</glossterm>
for the purpose of creating backups or keeping
<glossterm linkend="glossary-replica">replicas</glossterm> current.
</para>
@@ -1914,6 +1946,22 @@
</glossdef>
</glossentry>
+ <glossentry id="glossary-wal-receiver">
+ <glossterm>WAL receiver</glossterm>
+ <glossdef>
+ <para>
+ An auxiliary process that runs on a
+ <glossterm linkend="glossary-replica">replica</glossterm>
+ to receive and replay WAL from the primary server.
+ </para>
+
+ <para>
+ For more information, see
+ <xref linkend="warm-standby"/>.
+ </para>
+ </glossdef>
+ </glossentry>
+
<glossentry>
<glossterm>WAL segment</glossterm>
<glosssee otherterm="glossary-wal-file" />
--
2.17.0
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To: pgsql-hackers@postgresql.org
Cc: pryzby@telsasoft.com, alvherre@alvh.no-ip.org, bharath.rupireddyforpostgres@gmail.com, pgsql-hackers@lists.postgresql.org
Subject: Re: What are exactly bootstrap processes, auxiliary processes, standalone backends, normal backends(user sessions)?
In-Reply-To: <20210815003908.GP10479@telsasoft.com>
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