Date: Wed, 28 Aug 2019 12:22:38 -0400
From: Bruce Momjian <bruce@momjian.us>
To: PostgreSQL-documentation <pgsql-docs@postgresql.org>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Subject: Most-common value docs in PG 12
Message-ID: <20190828162238.GA8360@momjian.us>
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Our docs for most-common values in PG 12 has:

-->	CREATE STATISTICS stts3 (mcv) ON state, city FROM zipcodes;
	
	ANALYZE zipcodes;
	
	SELECT m.* FROM pg_statistic_ext join pg_statistic_ext_data on (oid = stxoid),
	                pg_mcv_list_items(stxdmcv) m WHERE stxname = 'stts3';
	
	 index |         values         | nulls | frequency | base_frequency
	-------+------------------------+-------+-----------+----------------
-->	     0 | {Washington, DC}       | {f,f} |  0.003467 |        2.7e-05
	     1 | {Apo, AE}              | {f,f} |  0.003067 |        1.9e-05
	     2 | {Houston, TX}          | {f,f} |  0.002167 |       0.000133
	     3 | {El Paso, TX}          | {f,f} |     0.002 |       0.000113

It seems pg_mcv_list_items() reports the column names in the order they
appear in the table, not in the order they appear in the CREATE
STATISTICS statement.  Same for psql \d:

	\d zipcodes
	             Table "public.zipcodes"
	 Column  | Type | Collation | Nullable | Default
	---------+------+-----------+----------+---------
	 city    | text |           |          |
	 state   | text |           |          |
	 zipcode | text |           |          |
	Statistics objects:
-->	    "public"."stts3" (mcv) ON city, state FROM zipcodes


If this is so, why don't we show the CREATE STATISTICS example as
city/state, and not state/city?

-- 
  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. +
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