From: Bruce Momjian <bruce@momjian.us>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: PostgreSQL-documentation <pgsql-docs@postgresql.org>
Subject: Re: Most-common value docs in PG 12
Date: Fri, 30 Aug 2019 19:28:04 -0400
Message-ID: <20190830232804.GA10645@momjian.us> (raw)
In-Reply-To: <20190828182541.zuexunho3hgb7vlw@development>
References: <20190828162238.GA8360@momjian.us>
<20190828182541.zuexunho3hgb7vlw@development>
On Wed, Aug 28, 2019 at 08:25:41PM +0200, Tomas Vondra wrote:
> On Wed, Aug 28, 2019 at 12:22:38PM -0400, Bruce Momjian wrote:
> > If this is so, why don't we show the CREATE STATISTICS example as
> > city/state, and not state/city?
>
> Yes, we deduplicate the attributes and store them sorted by attnum. I'm
> not sure it makes sense to change the example to match this order, which
> is mostly an implementation detail, though. It might be better to point
> out the order may not exactly match CREATE STATISTICS, and point users to
> what e.g. "\d" shows (because that will show the order as stored in the
> system catalog).
OK, how is this patch? I didn't mention psql since I think everyone
expects psql to show all information about tables and indexes.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ As you are, so once was I. As I am, so you will be. +
+ Ancient Roman grave inscription +
Attachments:mcv.diff (text/x-diff, 1.8K) downloaddiff --git a/doc/src/sgml/perform.sgml b/doc/src/sgml/perform.sgmlindex 8e165832b3..a645127e69 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.sgmlindex ec23a154d6..5b583aacb4 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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To: pgsql-docs@postgresql.org
Cc: bruce@momjian.us, tomas.vondra@2ndquadrant.com
Subject: Re: Most-common value docs in PG 12
In-Reply-To: <20190830232804.GA10645@momjian.us>
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