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
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