contrib/pgbench: Mark PRNG and random functions as PARALLEL RESTRICTED

In contrib/pgbench, the random distribution functions (random,
random_gaussian, random_exponential, random_zipfian, and random_poisson)
were previously marked PARALLEL SAFE, while setseed() was marked
PARALLEL UNSAFE.

Because these functions read and modify process-local PRNG state
(pgbench_prng_state), they cannot safely run inside parallel worker
processes without coordinating seed state. In particular, when running
regression tests under debug_parallel_query = regress (which is enabled
by default in PostgreSQL's macOS CI runner via PG_TEST_INITDB_EXTRA_OPTS),
the query planner wraps PARALLEL SAFE queries in a Gather node and offloads
evaluation to parallel workers. Those workers do not inherit the seed
initialized by setseed in the parallel leader, leading to unseeded,
divergent random values and regression test diff failures.

Mark both setseed and all random functions as PARALLEL RESTRICTED,
matching the parallel safety classification of core PostgreSQL's
random() and setseed() in pg_proc.dat.

Author: postsql

contrib/pgbench/pgbench--1.0.sql

@@ -7,42 +7,42 @@
 CREATE FUNCTION setseed(seed double precision)
 RETURNS void
 AS 'MODULE_PATHNAME', 'pgbench_setseed_double'
-LANGUAGE C STRICT VOLATILE PARALLEL UNSAFE;
+LANGUAGE C STRICT VOLATILE PARALLEL RESTRICTED;
 
 CREATE FUNCTION setseed(seed bigint)
 RETURNS void
 AS 'MODULE_PATHNAME', 'pgbench_setseed_int64'
-LANGUAGE C STRICT VOLATILE PARALLEL UNSAFE;
+LANGUAGE C STRICT VOLATILE PARALLEL RESTRICTED;
 
 -- Uniform Random
 CREATE FUNCTION random(min bigint, max bigint)
 RETURNS bigint
 AS 'MODULE_PATHNAME', 'pgbench_random_int64'
-LANGUAGE C STRICT VOLATILE PARALLEL SAFE;
+LANGUAGE C STRICT VOLATILE PARALLEL RESTRICTED;
 
 -- Gaussian (Normal) Random
 CREATE FUNCTION random_gaussian(min bigint, max bigint, parameter double precision)
 RETURNS bigint
 AS 'MODULE_PATHNAME', 'pgbench_random_gaussian_int64'
-LANGUAGE C STRICT VOLATILE PARALLEL SAFE;
+LANGUAGE C STRICT VOLATILE PARALLEL RESTRICTED;
 
 -- Exponential Random
 CREATE FUNCTION random_exponential(min bigint, max bigint, parameter double precision)
 RETURNS bigint
 AS 'MODULE_PATHNAME', 'pgbench_random_exponential_int64'
-LANGUAGE C STRICT VOLATILE PARALLEL SAFE;
+LANGUAGE C STRICT VOLATILE PARALLEL RESTRICTED;
 
 -- Zipfian Random
 CREATE FUNCTION random_zipfian(min bigint, max bigint, parameter double precision)
 RETURNS bigint
 AS 'MODULE_PATHNAME', 'pgbench_random_zipfian_int64'
-LANGUAGE C STRICT VOLATILE PARALLEL SAFE;
+LANGUAGE C STRICT VOLATILE PARALLEL RESTRICTED;
 
 -- Poisson Random
 CREATE FUNCTION random_poisson(center double precision)
 RETURNS bigint
 AS 'MODULE_PATHNAME', 'pgbench_random_poisson_int64'
-LANGUAGE C STRICT VOLATILE PARALLEL SAFE;
+LANGUAGE C STRICT VOLATILE PARALLEL RESTRICTED;
 
 -- MurmurHash2 (64-bit)
 CREATE FUNCTION hash_murmur2(val bigint, seed bigint DEFAULT 0)