5 files changed, 57 insertions, 5 deletions
diff --git a/src/include/c.h b/src/include/c.h
index bf4043dddf7..3a569c80602 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -355,13 +355,29 @@ typedef unsigned long long int uint64;
 
 /*
  * 128-bit signed and unsigned integers
- *		There currently is only a limited support for the type. E.g. 128bit
- *		literals and snprintf are not supported; but math is.
+ *		There currently is only limited support for such types.
+ *		E.g. 128bit literals and snprintf are not supported; but math is.
+ *		Also, because we exclude such types when choosing MAXIMUM_ALIGNOF,
+ *		it must be possible to coerce the compiler to allocate them on no
+ *		more than MAXALIGN boundaries.
  */
 #if defined(PG_INT128_TYPE)
-#define HAVE_INT128
-typedef PG_INT128_TYPE int128;
-typedef unsigned PG_INT128_TYPE uint128;
+#if defined(pg_attribute_aligned) || ALIGNOF_PG_INT128_TYPE <= MAXIMUM_ALIGNOF
+#define HAVE_INT128 1
+
+typedef PG_INT128_TYPE int128
+#if defined(pg_attribute_aligned)
+pg_attribute_aligned(MAXIMUM_ALIGNOF)
+#endif
+;
+
+typedef unsigned PG_INT128_TYPE uint128
+#if defined(pg_attribute_aligned)
+pg_attribute_aligned(MAXIMUM_ALIGNOF)
+#endif
+;
+
+#endif
 #endif
 
 /*
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 1e0583f7b15..f7ac5658cc4 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -27,6 +27,9 @@
 /* The normal alignment of `long long int', in bytes. */
 #undef ALIGNOF_LONG_LONG_INT
 
+/* The normal alignment of `PG_INT128_TYPE', in bytes. */
+#undef ALIGNOF_PG_INT128_TYPE
+
 /* The normal alignment of `short', in bytes. */
 #undef ALIGNOF_SHORT
 
diff --git a/src/include/pg_config.h.win32 b/src/include/pg_config.h.win32
index 0c2403f1bf0..d7dcb85af4f 100644
--- a/src/include/pg_config.h.win32
+++ b/src/include/pg_config.h.win32
@@ -34,6 +34,9 @@
 /* The alignment requirement of a `long long int'. */
 #define ALIGNOF_LONG_LONG_INT 8
 
+/* The normal alignment of `PG_INT128_TYPE', in bytes. */
+#undef ALIGNOF_PG_INT128_TYPE
+
 /* The alignment requirement of a `short'. */
 #define ALIGNOF_SHORT 2
 
diff --git a/src/test/regress/expected/select_parallel.out b/src/test/regress/expected/select_parallel.out
index 164c4bd61c9..72dd4204ace 100644
--- a/src/test/regress/expected/select_parallel.out
+++ b/src/test/regress/expected/select_parallel.out
@@ -99,6 +99,30 @@ explain (costs off)
    ->  Index Only Scan using tenk1_unique1 on tenk1
 (3 rows)
 
+-- check parallelized int8 aggregate (bug #14897)
+explain (costs off)
+select avg(aa::int8) from a_star;
+                     QUERY PLAN                      
+-----------------------------------------------------
+ Finalize Aggregate
+   ->  Gather
+         Workers Planned: 1
+         ->  Partial Aggregate
+               ->  Append
+                     ->  Parallel Seq Scan on a_star
+                     ->  Parallel Seq Scan on b_star
+                     ->  Parallel Seq Scan on c_star
+                     ->  Parallel Seq Scan on d_star
+                     ->  Parallel Seq Scan on e_star
+                     ->  Parallel Seq Scan on f_star
+(11 rows)
+
+select avg(aa::int8) from a_star;
+         avg         
+---------------------
+ 13.6538461538461538
+(1 row)
+
 -- test the sanity of parallel query after the active role is dropped.
 set force_parallel_mode=1;
 drop role if exists regress_parallel_worker;
diff --git a/src/test/regress/sql/select_parallel.sql b/src/test/regress/sql/select_parallel.sql
index e310c096811..af0cc558104 100644
--- a/src/test/regress/sql/select_parallel.sql
+++ b/src/test/regress/sql/select_parallel.sql
@@ -39,6 +39,12 @@ explain (costs off)
 	select  sum(parallel_restricted(unique1)) from tenk1
 	group by(parallel_restricted(unique1));
 
+-- check parallelized int8 aggregate (bug #14897)
+explain (costs off)
+select avg(aa::int8) from a_star;
+
+select avg(aa::int8) from a_star;
+
 -- test the sanity of parallel query after the active role is dropped.
 set force_parallel_mode=1;
 drop role if exists regress_parallel_worker;