Hi,
Statistics for range types are not currently exposed in pg_stats view
(i.e. STATISTIC_KIND_RANGE_LENGTH_HISTOGRAM and
STATISTIC_KIND_BOUNDS_HISTOGRAM).
Shouldn't they? If so, here is a patch for adding them.
The following is a simple example of what it looks like:
CREATE TABLE test(r int4range);
INSERT INTO test
SELECT int4range((random()*10)::integer,(10+random()*10)::integer)
FROM generate_series(1,10000);
SET default_statistics_target = 10;
ANALYZE test;
SELECT range_length_histogram, range_length_empty_frac,
range_bounds_histogram
FROM pg_stats
WHERE tablename = 'test' \gx
-[ RECORD 1
]-----------+------------------------------------------------------------------------------------------------------
range_length_histogram | {1,4,6,8,9,10,11,12,14,16,20}
range_length_empty_frac | {0.0036666666}
range_bounds_histogram |
{"[0,10)","[1,11)","[2,12)","[3,13)","[4,14)","[5,15)","[6,16)","[7,17)","[8,18)","[9,19)","[10,20)"}
Regards,
Egor Rogov.
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index f517a7d4af..4d037b590e 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -12877,6 +12877,36 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts
ppx
non-null elements. (Null for scalar types.)
</para></entry>
</row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>range_length_histogram</structfield> <type>anyarray</type>
+ </para>
+ <para>
+ A histogram of lengths of non-empty, non-null ranges.
+ (Null for non-range types.)
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>range_length_empty_frac</structfield> <type>float4</type>
+ </para>
+ <para>
+ A fraction of empty ranges. (Null for non-range types.)
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>range_bounds_histogram</structfield> <type>anyarray</type>
+ </para>
+ <para>
+ Histograms of lower and upper bounds of non-empty, non-null ranges,
+ combined into a single array of range values.
+ (Null for non-range types.)
+ </para></entry>
+ </row>
</tbody>
</tgroup>
</table>
diff --git a/src/backend/catalog/system_views.sql
b/src/backend/catalog/system_views.sql
index 999d984068..93fadfff15 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -243,7 +243,28 @@ CREATE VIEW pg_stats WITH (security_barrier) AS
WHEN stakind3 = 5 THEN stanumbers3
WHEN stakind4 = 5 THEN stanumbers4
WHEN stakind5 = 5 THEN stanumbers5
- END AS elem_count_histogram
+ END AS elem_count_histogram,
+ CASE
+ WHEN stakind1 = 6 THEN stavalues1
+ WHEN stakind2 = 6 THEN stavalues2
+ WHEN stakind3 = 6 THEN stavalues3
+ WHEN stakind4 = 6 THEN stavalues4
+ WHEN stakind5 = 6 THEN stavalues5
+ END AS range_length_histogram,
+ CASE
+ WHEN stakind1 = 6 THEN stanumbers1[1]
+ WHEN stakind2 = 6 THEN stanumbers2[1]
+ WHEN stakind3 = 6 THEN stanumbers3[1]
+ WHEN stakind4 = 6 THEN stanumbers4[1]
+ WHEN stakind5 = 6 THEN stanumbers5[1]
+ END AS range_length_empty_frac,
+ CASE
+ WHEN stakind1 = 7 THEN stavalues1
+ WHEN stakind2 = 7 THEN stavalues2
+ WHEN stakind3 = 7 THEN stavalues3
+ WHEN stakind4 = 7 THEN stavalues4
+ WHEN stakind5 = 7 THEN stavalues5
+ END AS range_bounds_histogram
FROM pg_statistic s JOIN pg_class c ON (c.oid = s.starelid)
JOIN pg_attribute a ON (c.oid = attrelid AND attnum = s.staattnum)
LEFT JOIN pg_namespace n ON (n.oid = c.relnamespace)
diff --git a/src/test/regress/expected/rules.out
b/src/test/regress/expected/rules.out
index e5ab11275d..780aefdc26 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2409,7 +2409,31 @@ pg_stats| SELECT n.nspname AS schemaname,
WHEN (s.stakind4 = 5) THEN s.stanumbers4
WHEN (s.stakind5 = 5) THEN s.stanumbers5
ELSE NULL::real[]
- END AS elem_count_histogram
+ END AS elem_count_histogram,
+ CASE
+ WHEN (s.stakind1 = 6) THEN s.stavalues1
+ WHEN (s.stakind2 = 6) THEN s.stavalues2
+ WHEN (s.stakind3 = 6) THEN s.stavalues3
+ WHEN (s.stakind4 = 6) THEN s.stavalues4
+ WHEN (s.stakind5 = 6) THEN s.stavalues5
+ ELSE NULL::anyarray
+ END AS range_length_histogram,
+ CASE
+ WHEN (s.stakind1 = 6) THEN s.stanumbers1[1]
+ WHEN (s.stakind2 = 6) THEN s.stanumbers2[1]
+ WHEN (s.stakind3 = 6) THEN s.stanumbers3[1]
+ WHEN (s.stakind4 = 6) THEN s.stanumbers4[1]
+ WHEN (s.stakind5 = 6) THEN s.stanumbers5[1]
+ ELSE NULL::real
+ END AS range_length_empty_frac,
+ CASE
+ WHEN (s.stakind1 = 7) THEN s.stavalues1
+ WHEN (s.stakind2 = 7) THEN s.stavalues2
+ WHEN (s.stakind3 = 7) THEN s.stavalues3
+ WHEN (s.stakind4 = 7) THEN s.stavalues4
+ WHEN (s.stakind5 = 7) THEN s.stavalues5
+ ELSE NULL::anyarray
+ END AS range_bounds_histogram
FROM (((pg_statistic s
JOIN pg_class c ON ((c.oid = s.starelid)))
JOIN pg_attribute a ON (((c.oid = a.attrelid) AND (a.attnum =
s.staattnum))))
