Hi,

While searching the definition of auxiliary processes, I noticed that the description of the WAL summarizer is incorrect. Additionally, I think it's better to add a description for the WAL writer similar to other Auxiliary
processes. What do you think?

# patch

```
diff --git a/doc/src/sgml/glossary.sgml b/doc/src/sgml/glossary.sgml
index a81c17a869..405fe6dc8b 100644
--- a/doc/src/sgml/glossary.sgml
+++ b/doc/src/sgml/glossary.sgml
@@ -164,6 +164,7 @@
the <glossterm linkend="glossary-wal-archiver">WAL archiver</glossterm>, the <glossterm linkend="glossary-wal-receiver">WAL receiver</glossterm> (but not the <glossterm linkend="glossary-wal-sender">WAL senders</glossterm>), + the <glossterm linkend="glossary-wal-summarizer">WAL summarizer</glossterm>, and the <glossterm linkend="glossary-wal-writer">WAL writer</glossterm>.
     </para>
    </glossdef>
@@ -2199,7 +2200,7 @@
    <glossterm>WAL summarizer (process)</glossterm>
    <glossdef>
     <para>
- A special <glossterm linkend="glossary-backend">backend process</glossterm> + An <glossterm linkend="glossary-auxiliary-proc">auxiliary process</glossterm>
      that summarizes WAL data for
<glossterm linkend="glossary-incremental-backup">incremental backups</glossterm>.
     </para>
@@ -2213,7 +2214,8 @@
    <glossterm>WAL writer (process)</glossterm>
    <glossdef>
     <para>
- A process that writes <glossterm linkend="glossary-wal-record">WAL records</glossterm> + An <glossterm linkend="glossary-auxiliary-proc">auxiliary process</glossterm> + that writes <glossterm linkend="glossary-wal-record">WAL records</glossterm> from <glossterm linkend="glossary-shared-memory">shared memory</glossterm> to
      <glossterm linkend="glossary-wal-file">WAL files</glossterm>.
     </para>
```

# additional information

As mentioned in miscadmin.h, WAL summarizer is one of auxiliary processes.
(postgres/src/include/miscadmin.h)
```
        /*
         * Auxiliary processes. These have PGPROC entries, but they are not
* attached to any particular database. There can be only one of each of
         * these running at a time.
         *
         * If you modify these, make sure to update NUM_AUXILIARY_PROCS and the
         * glossary in the docs.
         */
        B_ARCHIVER,
        B_BG_WRITER,
        B_CHECKPOINTER,
        B_STARTUP,
        B_WAL_RECEIVER,
        B_WAL_SUMMARIZER,
        B_WAL_WRITER,
```
Indeed, it calls InitAuxiliaryProcess() instead of InitProcess().

But, the description of WAL summarizer says that it's one of backend processes.
WAL summarizer (process)
A special backend process that summarizes WAL data for incremental backups.
https://www.postgresql.org/docs/devel/glossary.html


Regards,
--
Masahiro Ikeda
NTT DATA CORPORATION


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