5 files changed, 51 insertions, 5 deletions
diff --git a/src/include/c.h b/src/include/c.h
index 38c0ed7c304..d4dd86636f7 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -370,13 +370,29 @@ 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 c65dd7db215..f54bbedac5a 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 9a876f5f0ad..a5cecb3e07d 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 f3e8b565871..ecabd35cca6 100644
--- a/src/test/regress/expected/select_parallel.out
+++ b/src/test/regress/expected/select_parallel.out
@@ -444,6 +444,24 @@ select string4 from tenk1 order by string4 limit 5;
 
 reset max_parallel_workers;
 reset enable_hashagg;
+-- check parallelized int8 aggregate (bug #14897)
+explain (costs off)
+select avg(unique1::int8) from tenk1;
+                               QUERY PLAN                                
+-------------------------------------------------------------------------
+ Finalize Aggregate
+   ->  Gather
+         Workers Planned: 4
+         ->  Partial Aggregate
+               ->  Parallel Index Only Scan using tenk1_unique1 on tenk1
+(5 rows)
+
+select avg(unique1::int8) from tenk1;
+          avg          
+-----------------------
+ 4999.5000000000000000
+(1 row)
+
 -- test the sanity of parallel query after the active role is dropped.
 drop role if exists regress_parallel_worker;
 NOTICE:  role "regress_parallel_worker" does not exist, skipping
diff --git a/src/test/regress/sql/select_parallel.sql b/src/test/regress/sql/select_parallel.sql
index d2eee147e99..280c7876536 100644
--- a/src/test/regress/sql/select_parallel.sql
+++ b/src/test/regress/sql/select_parallel.sql
@@ -168,6 +168,12 @@ select string4 from tenk1 order by string4 limit 5;
 reset max_parallel_workers;
 reset enable_hashagg;
 
+-- check parallelized int8 aggregate (bug #14897)
+explain (costs off)
+select avg(unique1::int8) from tenk1;
+
+select avg(unique1::int8) from tenk1;
+
 -- test the sanity of parallel query after the active role is dropped.
 drop role if exists regress_parallel_worker;
 create role regress_parallel_worker;