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.
