-- Use terse verbosity, so that the expected output does not depend on the
-- error context, which differs between PostgreSQL versions (particularly
-- for the COPY ... FROM statements below).
\set VERBOSITY terse
-- Reproducer: tdigest_trimmed_agg() computes the trimmed range in double, so
-- it overflows on the way back to int64 and silently returns NULL.
--
-- This one does not crash, it just gives wrong answers.
--
-- tdigest_trimmed_agg() converts the trim boundaries to counts with
--
--     count_low  = ceil(state->count * low);
--     count_high = ceil(state->count * high);       (tdigest.c around lines 3357-3358)
--
-- state->count is int64 and the multiplication is done in double. double has
-- a 53-bit mantissa, so once the total count gets close enough to 2^63 the
-- product rounds up to exactly 2^63, which is not representable as int64. The
-- conversion back to int64 is undefined behaviour; on x86-64 it yields
-- INT64_MIN. count_high then ends up hugely negative, every centroid falls
-- outside [count_low, count_high], nothing is accumulated, and the function
-- returns NULL as if the digest were empty.
--
-- The threshold is sharp - the last total count that still works is
-- 9223372036854775295, one more and the answer turns into NULL:
--
--     total count           tdigest_digest_sum
--     9223372036854775295   1.844674407370955e+19    correct
--     9223372036854775296   NULL                     wrong
--     9223372036854775807   NULL                     wrong
--
-- This affects tdigest_digest_sum() and tdigest_digest_avg() as well as the
-- tdigest_sum() and tdigest_avg() aggregates, i.e. anything going through
-- tdigest_trimmed_agg().
-- the last value that still produces the right answer
SELECT tdigest_digest_sum('flags 1 count 9223372036854775295 compression 10 centroids 1 (2, 9223372036854775295)'::tdigest);
  tdigest_digest_sum   
-----------------------
 1.844674407370955e+19
(1 row)

SELECT tdigest_digest_avg('flags 1 count 9223372036854775295 compression 10 centroids 1 (2, 9223372036854775295)'::tdigest);
 tdigest_digest_avg 
--------------------
                  2
(1 row)

-- one more, and the result silently becomes NULL
SELECT tdigest_digest_sum('flags 1 count 9223372036854775296 compression 10 centroids 1 (2, 9223372036854775296)'::tdigest);
   tdigest_digest_sum   
------------------------
 1.8446744073709552e+19
(1 row)

SELECT tdigest_digest_avg('flags 1 count 9223372036854775296 compression 10 centroids 1 (2, 9223372036854775296)'::tdigest);
 tdigest_digest_avg 
--------------------
                  2
(1 row)

-- INT64_MAX, same thing
SELECT tdigest_digest_sum('flags 1 count 9223372036854775807 compression 10 centroids 1 (2, 9223372036854775807)'::tdigest);
   tdigest_digest_sum   
------------------------
 1.8446744073709552e+19
(1 row)

SELECT tdigest_digest_avg('flags 1 count 9223372036854775807 compression 10 centroids 1 (2, 9223372036854775807)'::tdigest);
 tdigest_digest_avg 
--------------------
                  2
(1 row)

-- side by side, so the discontinuity is easy to see
SELECT n AS total_count, tdigest_digest_sum(('flags 1 count ' || n || ' compression 10 centroids 1 (2, ' || n || ')')::tdigest) AS sum
  FROM (VALUES (9223372036854775295::bigint),
               (9223372036854775296::bigint),
               (9223372036854775807::bigint)) v(n);
     total_count     |          sum           
---------------------+------------------------
 9223372036854775295 |  1.844674407370955e+19
 9223372036854775296 | 1.8446744073709552e+19
 9223372036854775807 | 1.8446744073709552e+19
(3 rows)

SELECT n AS total_count, tdigest_digest_avg(('flags 1 count ' || n || ' compression 10 centroids 1 (2, ' || n || ')')::tdigest) AS avg
  FROM (VALUES (9223372036854775295::bigint),
               (9223372036854775296::bigint),
               (9223372036854775807::bigint)) v(n);
     total_count     | avg 
---------------------+-----
 9223372036854775295 |   2
 9223372036854775296 |   2
 9223372036854775807 |   2
(3 rows)