should be it

external/duckdb/test/sql/aggregate/aggregates/histogram_exact.test

@@ -0,0 +1,99 @@
+# name: test/sql/aggregate/aggregates/histogram_exact.test
+# description: Test histogram_exact
+# group: [aggregates]
+
+statement ok
+PRAGMA enable_verification
+
+statement ok
+CREATE TABLE obs(n BIGINT);
+
+statement ok
+INSERT INTO obs VALUES (0), (5), (7), (12), (20), (23), (24), (25), (26), (28), (31), (34), (36), (41), (47)
+
+# histogram_exact finds exact matches only, and puts everything else into the "other" category
+# the value of the other category depends on the data type of the bin
+# for integer values it is the highest value of the type
+query I
+SELECT histogram_exact(n, [10, 20, 30, 40, 50]) FROM obs
+----
+{10=0, 20=1, 30=0, 40=0, 50=0, 9223372036854775807=14}
+
+# for doubles/dates/timestamps it is infinite
+query I
+SELECT histogram_exact(n::double, [10, 20, 30, 40, 50]) FROM obs
+----
+{10.0=0, 20.0=1, 30.0=0, 40.0=0, 50.0=0, inf=14}
+
+query I
+SELECT histogram_exact((date '2000-01-01' + interval (n) days)::date, [date '2000-01-01' + interval (x) days for x in [10, 20, 30, 40, 50]]) FROM obs
+----
+{2000-01-11=0, 2000-01-21=1, 2000-01-31=0, 2000-02-10=0, 2000-02-20=0, infinity=14}
+
+# for strings it is the empty string
+query I
+SELECT histogram_exact(n::varchar, [10, 20, 30, 40, 50]) FROM obs
+----
+{10=0, 20=1, 30=0, 40=0, 50=0, ''=14}
+
+# for lists it is an empty list
+query I
+SELECT histogram_exact([n], [[x] for x in [10, 20, 30, 40, 50]]) FROM obs
+----
+{[10]=0, [20]=1, [30]=0, [40]=0, [50]=0, []=14}
+
+# we can use the function "is_histogram_other_bin" to check if it is this other bin
+query II
+SELECT case when is_histogram_other_bin(bin) then '(other values)' else bin::varchar end as bin,
+       count
+FROM (
+	SELECT UNNEST(map_keys(hist)) AS bin, UNNEST(map_values(hist)) AS count
+	FROM (SELECT histogram_exact(n, [10, 20, 30, 40, 50]) AS hist FROM obs)
+)
+----
+10	0
+20	1
+30	0
+40	0
+50	0
+(other values)	14
+
+query II
+SELECT case when is_histogram_other_bin(bin) then '(other values)' else bin::varchar end as bin,
+       count
+FROM (
+	SELECT UNNEST(map_keys(hist)) AS bin, UNNEST(map_values(hist)) AS count
+	FROM (SELECT histogram(n, [10, 20, 30, 40]) AS hist FROM obs)
+)
+----
+10	3
+20	2
+30	5
+40	3
+(other values)	2
+
+# when there are no other values the other bin is omitted from the result
+query I
+SELECT histogram_exact(r, [0, 1, 2, 3]) FROM range(4) t(r);
+----
+{0=1, 1=1, 2=1, 3=1}
+
+query I
+SELECT is_histogram_other_bin(NULL)
+----
+NULL
+
+query I
+SELECT is_histogram_other_bin([[1]])
+----
+false
+
+query I
+SELECT is_histogram_other_bin([]::INT[][][])
+----
+true
+
+query I
+SELECT is_histogram_other_bin({'i': NULL::INT[][]})
+----
+true