From 737f226842748cf946cad3bd30aadfd0c03ad16f Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Mon, 30 Sep 2019 13:44:22 -0400
Subject: [PATCH] docs: adjust multi-column most-common-value statistics
This commit adds a mention that the order of columns specified during
multi-column most-common-value statistics is insignificant, and tries to
simplify examples.
Discussion: https://postgr.es/m/20190828162238.GA8360@momjian.us
Backpatch-through: 12
---
doc/src/sgml/perform.sgml | 6 +++---
doc/src/sgml/ref/create_statistics.sgml | 3 ++-
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/doc/src/sgml/perform.sgml b/doc/src/sgml/perform.sgml
index 763337b0e1d..715aff63c80 100644
--- a/doc/src/sgml/perform.sgml
+++ b/doc/src/sgml/perform.sgml
@@ -1172,7 +1172,7 @@ WHERE tablename = 'road';
<para>
Here is an example of collecting functional-dependency statistics:
<programlisting>
-CREATE STATISTICS stts (dependencies) ON zip, city FROM zipcodes;
+CREATE STATISTICS stts (dependencies) ON city, zip FROM zipcodes;
ANALYZE zipcodes;
@@ -1262,7 +1262,7 @@ SELECT * FROM zipcodes WHERE city = 'San Francisco' AND zip = '90210';
Continuing the previous example, the n-distinct counts in a
table of ZIP codes might look like the following:
<programlisting>
-CREATE STATISTICS stts2 (ndistinct) ON zip, state, city FROM zipcodes;
+CREATE STATISTICS stts2 (ndistinct) ON city, state, zip FROM zipcodes;
ANALYZE zipcodes;
@@ -1317,7 +1317,7 @@ nd | {"1, 2": 33178, "1, 5": 33178, "2, 5": 27435, "1, 2, 5": 33178}
a function is required for inspection of MCV contents):
<programlisting>
-CREATE STATISTICS stts3 (mcv) ON state, city FROM zipcodes;
+CREATE STATISTICS stts3 (mcv) ON city, state FROM zipcodes;
ANALYZE zipcodes;
diff --git a/doc/src/sgml/ref/create_statistics.sgml b/doc/src/sgml/ref/create_statistics.sgml
index ec23a154d68..5b583aacb43 100644
--- a/doc/src/sgml/ref/create_statistics.sgml
+++ b/doc/src/sgml/ref/create_statistics.sgml
@@ -98,7 +98,8 @@ CREATE STATISTICS [ IF NOT EXISTS ] <replaceable class="parameter">statistics_na
<listitem>
<para>
The name of a table column to be covered by the computed statistics.
- At least two column names must be given.
+ At least two column names must be given; the order of the column names
+ is insignificant.
</para>
</listitem>
</varlistentry>
--
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