Date: Mon, 6 Apr 2020 11:34:20 -0500
From: Justin Pryzby <pryzby@telsasoft.com>
To: Julien Rouhaud <rjuju123@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>,
	Kyotaro Horiguchi <horikyota.ntt@gmail.com>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
	Dilip Kumar <dilipbalaut@gmail.com>,
	Kirill Bychik <kirill.bychik@gmail.com>,
	Fujii Masao <masao.fujii@oss.nttdata.com>
Subject: Re: User Interface for WAL usage data
Message-ID: <20200406163420.GE2228@telsasoft.com>
References: 
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 <20200402054120.GC14618@telsasoft.com>
 <20200402.145826.78549992113208057.horikyota.ntt@gmail.com>
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On Thu, Apr 02, 2020 at 08:29:31AM +0200, Julien Rouhaud wrote:
> > > "full page records" seems to be showing the number of full page
> > > images, not the record having full page images.
> >
> > I am not sure what exactly is a difference but it is the records
> > having full page images.  Julien correct me if I am wrong.

> Obviously previous complaints about the meaning and parsability of
> "full page writes" should be addressed here for consistency.

There's a couple places that say "full page image records" which I think is
language you were trying to avoid.  It's the number of pages, not the number of
records, no ?  I see explain and autovacuum say what I think is wanted, but
these say the wrong thing?  Find attached slightly larger patch.

$ git grep 'image record'
contrib/pg_stat_statements/pg_stat_statements.c:        int64           wal_num_fpw;    /* # of WAL full page image records generated */
doc/src/sgml/ref/explain.sgml:      number of records, number of full page image records and amount of WAL

-- 
Justin

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Content-Disposition: attachment; filename="v1-0001-doc-WAL-usage.patch"

From 6819c8c61c7fe2294b132a72c3897dc5cb801c4f Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Mon, 6 Apr 2020 11:28:08 -0500
Subject: [PATCH v1] doc: WAL usage

See also:
6b466bf5f2bea0c89fab54eef696bcfc7ecdafd7
33e05f89c53e5a1533d624046bb6fb0da7bb7141
---
 contrib/pg_stat_statements/pg_stat_statements.c | 2 +-
 doc/src/sgml/pgstatstatements.sgml              | 6 +++---
 doc/src/sgml/ref/explain.sgml                   | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 04abdab904..3bcf34c669 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -189,7 +189,7 @@ typedef struct Counters
 	double		blk_write_time; /* time spent writing, in msec */
 	double		usage;			/* usage factor */
 	int64		wal_records;	/* # of WAL records generated */
-	int64		wal_num_fpw;	/* # of WAL full page image records generated */
+	int64		wal_num_fpw;	/* # of WAL full page images generated */
 	uint64		wal_bytes;		/* total amount of WAL bytes generated */
 } Counters;
 
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index 3d26108649..de28016a02 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -269,7 +269,7 @@
       <entry><type>numeric</type></entry>
       <entry></entry>
       <entry>
-        Total amount of WAL bytes generated by the statement
+        Total number of WAL bytes generated by the statement
       </entry>
      </row>
 
@@ -278,7 +278,7 @@
       <entry><type>bigint</type></entry>
       <entry></entry>
       <entry>
-        Total count of WAL records generated by the statement
+        Total number of WAL records generated by the statement
       </entry>
      </row>
 
@@ -287,7 +287,7 @@
       <entry><type>bigint</type></entry>
       <entry></entry>
       <entry>
-        Total count of WAL full page writes generated by the statement
+        Total number of WAL full page writes generated by the statement
       </entry>
      </row>
 
diff --git a/doc/src/sgml/ref/explain.sgml b/doc/src/sgml/ref/explain.sgml
index 024ede4a8d..4a9f94d7f8 100644
--- a/doc/src/sgml/ref/explain.sgml
+++ b/doc/src/sgml/ref/explain.sgml
@@ -198,7 +198,7 @@ ROLLBACK;
     <listitem>
      <para>
       Include information on WAL record generation. Specifically, include the
-      number of records, number of full page image records and amount of WAL
+      number of records, number of full page images and number of WAL
       bytes generated.  In text format, only non-zero values are printed.  This
       parameter may only be used when <literal>ANALYZE</literal> is also
       enabled.  It defaults to <literal>FALSE</literal>.
-- 
2.17.0


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