CREATE OR REPLACE FUNCTION _timescaledb_internal.hist_sfunc (state INTERNAL, val DOUBLE PRECISION, MIN DOUBLE PRECISION, MAX DOUBLE PRECISION, nbuckets INTEGER)
RETURNS INTERNAL
AS '@MODULE_PATHNAME@', 'hist_sfunc'
LANGUAGE C IMMUTABLE PARALLEL SAFE;

CREATE OR REPLACE FUNCTION _timescaledb_internal.hist_combinefunc(state1 INTERNAL, state2 INTERNAL)
RETURNS INTERNAL
AS '@MODULE_PATHNAME@', 'hist_combinefunc'
LANGUAGE C IMMUTABLE PARALLEL SAFE;

CREATE OR REPLACE FUNCTION _timescaledb_internal.hist_serializefunc(INTERNAL)
RETURNS bytea
AS '@MODULE_PATHNAME@', 'hist_serializefunc'
LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE OR REPLACE FUNCTION _timescaledb_internal.hist_deserializefunc(bytea, INTERNAL)
RETURNS INTERNAL
AS '@MODULE_PATHNAME@', 'hist_deserializefunc'
LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE OR REPLACE FUNCTION _timescaledb_internal.hist_finalfunc(state INTERNAL, val DOUBLE PRECISION, MIN DOUBLE PRECISION, MAX DOUBLE PRECISION, nbuckets INTEGER)
RETURNS INTEGER[]
AS '@MODULE_PATHNAME@', 'hist_finalfunc'
LANGUAGE C IMMUTABLE PARALLEL SAFE;

-- Tell Postgres how to use the new function
DROP AGGREGATE IF EXISTS histogram (DOUBLE PRECISION, DOUBLE PRECISION, DOUBLE PRECISION, INTEGER);
CREATE AGGREGATE histogram (DOUBLE PRECISION, DOUBLE PRECISION, DOUBLE PRECISION, INTEGER) (
    SFUNC = _timescaledb_internal.hist_sfunc,
    STYPE = INTERNAL,
    COMBINEFUNC = _timescaledb_internal.hist_combinefunc,
    SERIALFUNC = _timescaledb_internal.hist_serializefunc,
    DESERIALFUNC = _timescaledb_internal.hist_deserializefunc,
    PARALLEL = SAFE,
    FINALFUNC = _timescaledb_internal.hist_finalfunc,
    FINALFUNC_EXTRA
);