Mark immutable functions in information schema as parallel safe

Also add opr_sanity check that all preloaded immutable functions are
parallel safe.  (Per discussion, this does not necessarily have to be
true for all possible such functions, but deviations would be unlikely
enough that maintaining such a test is reasonable.)

Reported-by: David Rowley <david.rowley@2ndquadrant.com>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>

src/backend/catalog/information_schema.sql

@@ -42,14 +42,14 @@ SET search_path TO information_schema;
 /* Expand any 1-D array into a set with integers 1..N */
 CREATE FUNCTION _pg_expandarray(IN anyarray, OUT x anyelement, OUT n int)
     RETURNS SETOF RECORD
-    LANGUAGE sql STRICT IMMUTABLE
+    LANGUAGE sql STRICT IMMUTABLE PARALLEL SAFE
     AS 'select $1[s], s - pg_catalog.array_lower($1,1) + 1
         from pg_catalog.generate_series(pg_catalog.array_lower($1,1),
                                         pg_catalog.array_upper($1,1),
                                         1) as g(s)';
 
 CREATE FUNCTION _pg_keysequal(smallint[], smallint[]) RETURNS boolean
-    LANGUAGE sql IMMUTABLE  -- intentionally not STRICT, to allow inlining
+    LANGUAGE sql IMMUTABLE PARALLEL SAFE  -- intentionally not STRICT, to allow inlining
     AS 'select $1 operator(pg_catalog.<@) $2 and $2 operator(pg_catalog.<@) $1';
 
 /* Given an index's OID and an underlying-table column number, return the
@@ -66,6 +66,7 @@ $$;
 CREATE FUNCTION _pg_truetypid(pg_attribute, pg_type) RETURNS oid
     LANGUAGE sql
     IMMUTABLE
+    PARALLEL SAFE
     RETURNS NULL ON NULL INPUT
     AS
 $$SELECT CASE WHEN $2.typtype = 'd' THEN $2.typbasetype ELSE $1.atttypid END$$;
@@ -73,6 +74,7 @@ $$SELECT CASE WHEN $2.typtype = 'd' THEN $2.typbasetype ELSE $1.atttypid END$$;
 CREATE FUNCTION _pg_truetypmod(pg_attribute, pg_type) RETURNS int4
     LANGUAGE sql
     IMMUTABLE
+    PARALLEL SAFE
     RETURNS NULL ON NULL INPUT
     AS
 $$SELECT CASE WHEN $2.typtype = 'd' THEN $2.typtypmod ELSE $1.atttypmod END$$;
@@ -82,6 +84,7 @@ $$SELECT CASE WHEN $2.typtype = 'd' THEN $2.typtypmod ELSE $1.atttypmod END$$;
 CREATE FUNCTION _pg_char_max_length(typid oid, typmod int4) RETURNS integer
     LANGUAGE sql
     IMMUTABLE
+    PARALLEL SAFE
     RETURNS NULL ON NULL INPUT
     AS
 $$SELECT
@@ -97,6 +100,7 @@ $$SELECT
 CREATE FUNCTION _pg_char_octet_length(typid oid, typmod int4) RETURNS integer
     LANGUAGE sql
     IMMUTABLE
+    PARALLEL SAFE
     RETURNS NULL ON NULL INPUT
     AS
 $$SELECT
@@ -112,6 +116,7 @@ $$SELECT
 CREATE FUNCTION _pg_numeric_precision(typid oid, typmod int4) RETURNS integer
     LANGUAGE sql
     IMMUTABLE
+    PARALLEL SAFE
     RETURNS NULL ON NULL INPUT
     AS
 $$SELECT
@@ -132,6 +137,7 @@ $$SELECT
 CREATE FUNCTION _pg_numeric_precision_radix(typid oid, typmod int4) RETURNS integer
     LANGUAGE sql
     IMMUTABLE
+    PARALLEL SAFE
     RETURNS NULL ON NULL INPUT
     AS
 $$SELECT
@@ -143,6 +149,7 @@ $$SELECT
 CREATE FUNCTION _pg_numeric_scale(typid oid, typmod int4) RETURNS integer
     LANGUAGE sql
     IMMUTABLE
+    PARALLEL SAFE
     RETURNS NULL ON NULL INPUT
     AS
 $$SELECT
@@ -158,6 +165,7 @@ $$SELECT
 CREATE FUNCTION _pg_datetime_precision(typid oid, typmod int4) RETURNS integer
     LANGUAGE sql
     IMMUTABLE
+    PARALLEL SAFE
     RETURNS NULL ON NULL INPUT
     AS
 $$SELECT
@@ -173,6 +181,7 @@ $$SELECT
 CREATE FUNCTION _pg_interval_type(typid oid, mod int4) RETURNS text
     LANGUAGE sql
     IMMUTABLE
+    PARALLEL SAFE
     RETURNS NULL ON NULL INPUT
     AS
 $$SELECT

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201704061
+#define CATALOG_VERSION_NO	201704062
 
 #endif

src/test/regress/expected/opr_sanity.out

@@ -733,6 +733,14 @@ order by 1;
  lowrite       |  955
 (13 rows)
 
+-- Check that all immutable functions are marked parallel safe
+SELECT p1.oid, p1.proname
+FROM pg_proc AS p1
+WHERE provolatile = 'i' AND proparallel = 'u';
+ oid | proname 
+-----+---------
+(0 rows)
+
 -- **************** pg_cast ****************
 -- Catch bogus values in pg_cast columns (other than cases detected by
 -- oidjoins test).

src/test/regress/sql/opr_sanity.sql

@@ -381,6 +381,11 @@ and pronamespace = (select oid from pg_catalog.pg_namespace
                     where nspname = 'pg_catalog')
 order by 1;
 
+-- Check that all immutable functions are marked parallel safe
+SELECT p1.oid, p1.proname
+FROM pg_proc AS p1
+WHERE provolatile = 'i' AND proparallel = 'u';
+
 
 -- **************** pg_cast ****************