diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index ef4345524a..1300c7bbaa 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -6373,6 +6373,28 @@ SCRAM-SHA-256$<iteration count>:&l
about those tables that are readable by the current user.
+
+ pg_statistic should not be readable by the
+ public, since even statistical information about a table's contents
+ might be considered sensitive. (Example: minimum and maximum values
+ of a salary column might be quite interesting.)
+ pg_stats
+ is a publicly readable view on
+ pg_statistic that only exposes information
+ about those tables that are readable by the current user.
+
+
+
+ Similarly, pg_statistic_ext_data should not be
+ readable by the public, since the contents might be considered sensitive.
+ (Example: most common combination of values in columns might be quite
+ interesting.)
+ pg_stats_ext
+ is a publicly readable view on pg_statistic_ext_data
+ (after joining with pg_statistic_ext) that only exposes
+ information about those tables and columns that are readable by the current user.
+
+
pg_statistic Columns
@@ -8343,6 +8365,11 @@ SCRAM-SHA-256$<iteration count>:&l
planner statistics
+
+ pg_stats_ext
+ extended planner statistics
+
+
pg_tablestables
@@ -10922,6 +10949,171 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx
+
+ pg_stats_ext
+
+
+ pg_stats_ext
+
+
+
+ The view pg_stats_ext provides access to
+ the information stored in the pg_statistic_ext
+ and pg_statistic_ext_data
+ catalogs. This view allows access only to rows of
+ pg_statistic_ext and pg_statistic_ext_data
+ that correspond to tables the user has permission to read, and therefore
+ it is safe to allow public read access to this view.
+
+
+
+ pg_stats_ext is also designed to present the
+ information in a more readable format than the underlying catalog
+ — at the cost that its schema must be extended whenever new types
+ of extended statistics are added to pg_statistic_ext.
+
+
+
+ pg_stats_ext Columns
+
+
+
+
+ Name
+ Type
+ References
+ Description
+
+
+
+
+ schemaname
+ name
+ pg_namespace.nspname
+ Name of schema containing table
+
+
+
+ tablename
+ name
+ pg_class.relname
+ Name of table
+
+
+
+ statistics_schemaname
+ name
+ pg_namespace.nspname
+ Name of schema containing extended statistic
+
+
+
+ statistics_name
+ name
+ pg_statistic_ext.stxname
+ Name of extended statistics
+
+
+
+ statistics_owner
+ oid
+ pg_authid.oid
+ Owner of the extended statistics
+
+
+
+ attnames
+ name[]
+ pg_attribute.attname
+ Names of the column the extended statistics is defined on
+
+
+
+ kinds
+ text[]
+
+ Types of exdended statistics enabled for this record
+
+
+
+ n_distinct
+ pg_ndistinct
+
+ N-distinct counts for combinations of columns. If greater than
+ zero, the estimated number of distinct values in the combination. If
+ less than zero, the negative of the number of distinct values divided
+ by the number of rows.
+ (The negated form is used when ANALYZE believes that
+ the number of distinct values is likely to increase as the table grows;
+ the positive form is used when the column seems to have a fixed number
+ of possible values.) For example, -1 indicates a unique combination of
+ columns in which the number of distinct combinations is the same as the
+ number of rows.
+
+
+
+
+ dependencies
+ pg_dependencies
+
+ Functional dependency statistics
+
+
+
+ most_common_vals
+ anyarray
+
+
+ A list of the most common combinations in the columns. (Null if
+ no values seem to be more common than any others.)
+
+
+
+
+ most_common_val_nulls
+ anyarray
+
+
+ A list of NULL flags for the most common combinations of values.
+ (Null when most_common_vals is.)
+
+
+
+
+ most_common_freqs
+ real[]
+
+
+ A list of the frequencies of the most common combinations,
+ i.e., number of occurrences of each divided by total number of rows.
+ (Null when most_common_vals is.)
+
+
+
+
+ most_common_base_freqs
+ real[]
+
+
+ A list of the base frequencies of the most common combinations,
+ i.e., product of per-value frequencies.
+ (Null when most_common_vals is.)
+
+
+
+
+
+
+
+ The maximum number of entries in the array fields can be controlled on a
+ column-by-column basis using the ALTER TABLE SET STATISTICS
+ command, or globally by setting the
+ run-time parameter.
+
+
+
+
pg_tables
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 78a103cdb9..c889890118 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -253,6 +253,47 @@ CREATE VIEW pg_stats WITH (security_barrier) AS
REVOKE ALL on pg_statistic FROM public;
+CREATE VIEW pg_stats_ext WITH (security_barrier) AS
+ SELECT cn.nspname AS schemaname,
+ c.relname AS tablename,
+ sn.nspname AS statistics_schemaname,
+ s.stxname AS statistics_name,
+ pg_get_userbyid(s.stxowner) AS statistics_owner,
+ ( SELECT array_agg(a.attname ORDER BY a.attnum)
+ FROM unnest(s.stxkeys) k
+ JOIN pg_attribute a
+ ON (a.attrelid = s.stxrelid AND a.attnum = k)
+ ) AS attnames,
+ s.stxkind AS kinds,
+ sd.stxdndistinct AS n_distinct,
+ sd.stxddependencies AS dependencies,
+ m.most_common_vals,
+ m.most_common_val_nulls,
+ m.most_common_freqs,
+ m.most_common_base_freqs
+ FROM pg_statistic_ext s JOIN pg_class c ON (c.oid = s.stxrelid)
+ JOIN pg_statistic_ext_data sd ON (s.oid = sd.stxoid)
+ LEFT JOIN pg_namespace cn ON (cn.oid = c.relnamespace)
+ LEFT JOIN pg_namespace sn ON (sn.oid = s.stxnamespace)
+ LEFT JOIN LATERAL
+ ( SELECT array_agg(values) AS most_common_vals,
+ array_agg(nulls) AS most_common_val_nulls,
+ array_agg(frequency) AS most_common_freqs,
+ array_agg(base_frequency) AS most_common_base_freqs
+ FROM pg_mcv_list_items(sd.stxdmcv)
+ ) m ON sd.stxdmcv IS NOT NULL
+ WHERE NOT EXISTS
+ ( SELECT 1
+ FROM unnest(stxkeys) k
+ JOIN pg_attribute a
+ ON (a.attrelid = s.stxrelid AND a.attnum = k)
+ WHERE NOT has_column_privilege(c.oid, a.attnum, 'select') )
+ AND (c.relrowsecurity = false OR NOT row_security_active(c.oid));
+
+REVOKE ALL on pg_statistic_ext FROM public;
+GRANT SELECT (oid, stxrelid, stxname, stxnamespace, stxowner, stxkeys, stxkind)
+ ON pg_statistic_ext TO public;
+
CREATE VIEW pg_publication_tables AS
SELECT
P.pubname AS pubname,
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index e034506751..ed20a4faaf 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
*/
/* yyyymmddN */
-#define CATALOG_VERSION_NO 201906151
+#define CATALOG_VERSION_NO 201906152
#endif
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 7d365c48d1..210e9cd146 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2284,6 +2284,35 @@ pg_stats| SELECT n.nspname AS schemaname,
JOIN pg_attribute a ON (((c.oid = a.attrelid) AND (a.attnum = s.staattnum))))
LEFT JOIN pg_namespace n ON ((n.oid = c.relnamespace)))
WHERE ((NOT a.attisdropped) AND has_column_privilege(c.oid, a.attnum, 'select'::text) AND ((c.relrowsecurity = false) OR (NOT row_security_active(c.oid))));
+pg_stats_ext| SELECT cn.nspname AS schemaname,
+ c.relname AS tablename,
+ sn.nspname AS statistics_schemaname,
+ s.stxname AS statistics_name,
+ pg_get_userbyid(s.stxowner) AS statistics_owner,
+ ( SELECT array_agg(a.attname ORDER BY a.attnum) AS array_agg
+ FROM (unnest(s.stxkeys) k(k)
+ JOIN pg_attribute a ON (((a.attrelid = s.stxrelid) AND (a.attnum = k.k))))) AS attnames,
+ s.stxkind AS kinds,
+ sd.stxdndistinct AS n_distinct,
+ sd.stxddependencies AS dependencies,
+ m.most_common_vals,
+ m.most_common_val_nulls,
+ m.most_common_freqs,
+ m.most_common_base_freqs
+ FROM (((((pg_statistic_ext s
+ JOIN pg_class c ON ((c.oid = s.stxrelid)))
+ JOIN pg_statistic_ext_data sd ON ((s.oid = sd.stxoid)))
+ LEFT JOIN pg_namespace cn ON ((cn.oid = c.relnamespace)))
+ LEFT JOIN pg_namespace sn ON ((sn.oid = s.stxnamespace)))
+ LEFT JOIN LATERAL ( SELECT array_agg(pg_mcv_list_items."values") AS most_common_vals,
+ array_agg(pg_mcv_list_items.nulls) AS most_common_val_nulls,
+ array_agg(pg_mcv_list_items.frequency) AS most_common_freqs,
+ array_agg(pg_mcv_list_items.base_frequency) AS most_common_base_freqs
+ FROM pg_mcv_list_items(sd.stxdmcv) pg_mcv_list_items(index, "values", nulls, frequency, base_frequency)) m ON ((sd.stxdmcv IS NOT NULL)))
+ WHERE ((NOT (EXISTS ( SELECT 1
+ FROM (unnest(s.stxkeys) k(k)
+ JOIN pg_attribute a ON (((a.attrelid = s.stxrelid) AND (a.attnum = k.k))))
+ WHERE (NOT has_column_privilege(c.oid, a.attnum, 'select'::text))))) AND ((c.relrowsecurity = false) OR (NOT row_security_active(c.oid))));
pg_tables| SELECT n.nspname AS schemaname,
c.relname AS tablename,
pg_get_userbyid(c.relowner) AS tableowner,