doc: explain pgstatindex fragmentation
Started by Benoit Lobréau12 months ago3 messages
Hi,
I like the clarification but I think that:
A higher <literal>leaf_fragmentation</literal> indicates that the
physical order of the index leaf
pages increasingly deviates from their logical order.
Would be cleaner than:
The higher <literal>leaf_fragmentation</literal> is, the less the
physical order
of the index leaf pages corresponds to the logical order we would have
just after
a <command>REINDEX</command>.
--
Benoit Lobréau
Consultant
http://dalibo.com
Re: doc: explain pgstatindex fragmentation
Here is an updated patch to save you some time.
--
Benoit Lobréau
Consultant
http://dalibo.com
Attachments:
0001-doc-explain-pgstatindex-fragmentation.patchtext/x-patch; charset=UTF-8; name=0001-doc-explain-pgstatindex-fragmentation.patchDownload
From 5d89ca0a36e98d1e5be858166a8394c09e0fa129 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Yhuel?= <frederic.yhuel@dalibo.com>
Date: Tue, 5 Nov 2024 17:59:44 +0100
Subject: [PATCH] doc: explain pgstatindex fragmentation
It was quite hard to guess what leaf_fragmentation meant without looking
at pgstattuple's code. This patch aims to give to the user a better
idea of what it means.
---
doc/src/sgml/pgstattuple.sgml | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/doc/src/sgml/pgstattuple.sgml b/doc/src/sgml/pgstattuple.sgml
index 4071da4ed94..280f1ac9ce8 100644
--- a/doc/src/sgml/pgstattuple.sgml
+++ b/doc/src/sgml/pgstattuple.sgml
@@ -277,6 +277,13 @@ leaf_fragmentation | 0
page-by-page, and should not be expected to represent an
instantaneous snapshot of the whole index.
</para>
+
+ <para>
+ <literal>avg_leaf_density</literal> can be seen as the inverse of bloat,
+ while <literal>leaf_fragmentation</literal> represents a measure of disorder.
+ A higher <literal>leaf_fragmentation</literal> indicates that the physical
+ order of the index leaf pages increasingly deviates from their logical order.
+ </para>
</listitem>
</varlistentry>
--
2.48.1
