rationalize-attribute-fixed-part-size.patch

diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index f1f4423..67d3d3d 100644
*** a/src/backend/access/common/tupdesc.c
--- b/src/backend/access/common/tupdesc.c
*************** CreateTemplateTupleDesc(int natts, bool 
*** 57,65 ****
  	 * since we declare the array elements as FormData_pg_attribute for
  	 * notational convenience.  However, we only guarantee that the first
  	 * ATTRIBUTE_FIXED_PART_SIZE bytes of each entry are valid; most code that
! 	 * copies tupdesc entries around copies just that much.  In principle that
! 	 * could be less due to trailing padding, although with the current
! 	 * definition of pg_attribute there probably isn't any padding.
  	 */
  	desc = (TupleDesc) palloc(offsetof(struct tupleDesc, attrs) +
  							  natts * sizeof(FormData_pg_attribute));
--- 57,69 ----
  	 * since we declare the array elements as FormData_pg_attribute for
  	 * notational convenience.  However, we only guarantee that the first
  	 * ATTRIBUTE_FIXED_PART_SIZE bytes of each entry are valid; most code that
! 	 * copies tupdesc entries around copies just that much.  Currently, that
! 	 * symbol is just defined as sizeof(FormData_pg_attribute) anyway, so this
! 	 * distinction is somewhat academic.  If there were any trailing padding
! 	 * space in FormData_pg_attribute, it'd be possible to define
! 	 * ATTRIBUTE_FIXED_PART_SIZE to omit it, but that might cause complaints
! 	 * from valgrind about copying uninitialized padding bytes, so it seems
! 	 * best to keep them the same.
  	 */
  	desc = (TupleDesc) palloc(offsetof(struct tupleDesc, attrs) +
  							  natts * sizeof(FormData_pg_attribute));
diff --git a/src/include/catalog/pg_attribute.h b/src/include/catalog/pg_attribute.h
index 6104254..739e784 100644
*** a/src/include/catalog/pg_attribute.h
--- b/src/include/catalog/pg_attribute.h
*************** CATALOG(pg_attribute,1249) BKI_BOOTSTRAP
*** 175,183 ****
   * guaranteed-not-null part of a pg_attribute row.  This is in fact as much
   * of the row as gets copied into tuple descriptors, so don't expect you
   * can access fields beyond attcollation except in a real tuple!
   */
  #define ATTRIBUTE_FIXED_PART_SIZE \
! 	(offsetof(FormData_pg_attribute,attcollation) + sizeof(Oid))
  
  /* ----------------
   *		Form_pg_attribute corresponds to a pointer to a tuple with
--- 175,188 ----
   * guaranteed-not-null part of a pg_attribute row.  This is in fact as much
   * of the row as gets copied into tuple descriptors, so don't expect you
   * can access fields beyond attcollation except in a real tuple!
+  *
+  * Since the introduction of CATALOG_VARLEN, this can just be defined as
+  * sizeof(FormData_pg_attribute).  It's possible that that would include
+  * some trailing alignment padding, but that's harmless (and anyway there
+  * is no such padding given the current contents of pg_attribute).
   */
  #define ATTRIBUTE_FIXED_PART_SIZE \
! 	sizeof(FormData_pg_attribute)
  
  /* ----------------
   *		Form_pg_attribute corresponds to a pointer to a tuple with