*** a/src/backend/utils/adt/arrayfuncs.c
--- b/src/backend/utils/adt/arrayfuncs.c
***************
*** 1551,1557 **** array_send(PG_FUNCTION_ARGS)
  Datum
  array_ndims(PG_FUNCTION_ARGS)
  {
! 	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
  
  	/* Sanity check: does it look like an array at all? */
  	if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
--- 1551,1557 ----
  Datum
  array_ndims(PG_FUNCTION_ARGS)
  {
! 	ArrayType  *v = PG_GETARG_ARRAYTYPE_HEADER_P(0);
  
  	/* Sanity check: does it look like an array at all? */
  	if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
***************
*** 1567,1573 **** array_ndims(PG_FUNCTION_ARGS)
  Datum
  array_dims(PG_FUNCTION_ARGS)
  {
! 	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
  	char	   *p;
  	int			i;
  	int		   *dimv,
--- 1567,1573 ----
  Datum
  array_dims(PG_FUNCTION_ARGS)
  {
! 	ArrayType  *v = PG_GETARG_ARRAYTYPE_HEADER_P(0);
  	char	   *p;
  	int			i;
  	int		   *dimv,
***************
*** 1605,1611 **** array_dims(PG_FUNCTION_ARGS)
  Datum
  array_lower(PG_FUNCTION_ARGS)
  {
! 	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
  	int			reqdim = PG_GETARG_INT32(1);
  	int		   *lb;
  	int			result;
--- 1605,1611 ----
  Datum
  array_lower(PG_FUNCTION_ARGS)
  {
! 	ArrayType  *v = PG_GETARG_ARRAYTYPE_HEADER_P(0);
  	int			reqdim = PG_GETARG_INT32(1);
  	int		   *lb;
  	int			result;
***************
*** 1632,1638 **** array_lower(PG_FUNCTION_ARGS)
  Datum
  array_upper(PG_FUNCTION_ARGS)
  {
! 	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
  	int			reqdim = PG_GETARG_INT32(1);
  	int		   *dimv,
  			   *lb;
--- 1632,1638 ----
  Datum
  array_upper(PG_FUNCTION_ARGS)
  {
! 	ArrayType  *v = PG_GETARG_ARRAYTYPE_HEADER_P(0);
  	int			reqdim = PG_GETARG_INT32(1);
  	int		   *dimv,
  			   *lb;
***************
*** 1662,1668 **** array_upper(PG_FUNCTION_ARGS)
  Datum
  array_length(PG_FUNCTION_ARGS)
  {
! 	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
  	int			reqdim = PG_GETARG_INT32(1);
  	int		   *dimv;
  	int			result;
--- 1662,1668 ----
  Datum
  array_length(PG_FUNCTION_ARGS)
  {
! 	ArrayType  *v = PG_GETARG_ARRAYTYPE_HEADER_P(0);
  	int			reqdim = PG_GETARG_INT32(1);
  	int		   *dimv;
  	int			result;
*** a/src/include/utils/array.h
--- b/src/include/utils/array.h
***************
*** 119,126 **** typedef struct ArrayMapState
--- 119,129 ----
   */
  #define DatumGetArrayTypeP(X)		  ((ArrayType *) PG_DETOAST_DATUM(X))
  #define DatumGetArrayTypePCopy(X)	  ((ArrayType *) PG_DETOAST_DATUM_COPY(X))
+ #define DatamGetArrayTypeHeaderP(X) \
+ 	((ArrayType *) PG_DETOAST_DATUM_SLICE(X, 0, ARR_MAX_HEADER_SIZE))
  #define PG_GETARG_ARRAYTYPE_P(n)	  DatumGetArrayTypeP(PG_GETARG_DATUM(n))
  #define PG_GETARG_ARRAYTYPE_P_COPY(n) DatumGetArrayTypePCopy(PG_GETARG_DATUM(n))
+ #define PG_GETARG_ARRAYTYPE_HEADER_P(n)	  DatamGetArrayTypeHeaderP(PG_GETARG_DATUM(n))
  #define PG_RETURN_ARRAYTYPE_P(x)	  PG_RETURN_POINTER(x)
  
  /*
***************
*** 172,177 **** typedef struct ArrayMapState
--- 175,185 ----
  #define ARR_DATA_PTR(a) \
  		(((char *) (a)) + ARR_DATA_OFFSET(a))
  
+ /*
+  * Calculate the maximum size a header of an array can be
+  */
+ #define ARR_MAX_HEADER_SIZE \
+ 		ARR_OVERHEAD_NONULLS(MAXDIM)
  
  /*
   * GUC parameter