Support "expanded" objects, particularly arrays, for better performance.

This patch introduces the ability for complex datatypes to have an
in-memory representation that is different from their on-disk format.
On-disk formats are typically optimized for minimal size, and in any case
they can't contain pointers, so they are often not well-suited for
computation.  Now a datatype can invent an "expanded" in-memory format
that is better suited for its operations, and then pass that around among
the C functions that operate on the datatype.  There are also provisions
(rudimentary as yet) to allow an expanded object to be modified in-place
under suitable conditions, so that operations like assignment to an element
of an array need not involve copying the entire array.

The initial application for this feature is arrays, but it is not hard
to foresee using it for other container types like JSON, XML and hstore.
I have hopes that it will be useful to PostGIS as well.

In this initial implementation, a few heuristics have been hard-wired
into plpgsql to improve performance for arrays that are stored in
plpgsql variables.  We would like to generalize those hacks so that
other datatypes can obtain similar improvements, but figuring out some
appropriate APIs is left as a task for future work.  (The heuristics
themselves are probably not optimal yet, either, as they sometimes
force expansion of arrays that would be better left alone.)

Preliminary performance testing shows impressive speed gains for plpgsql
functions that do element-by-element access or update of large arrays.
There are other cases that get a little slower, as a result of added array
format conversions; but we can hope to improve anything that's annoyingly
bad.  In any case most applications should see a net win.

Tom Lane, reviewed by Andres Freund

1 files changed, 599 insertions, 392 deletions

diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index 9117a5515a9..82d79977d7a 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -20,11 +20,15 @@
 #endif
 #include <math.h>
 
+/* See arrayaccess.h */
+#define ARRAYACCESS_INCLUDE_DEFINITIONS
+
 #include "access/htup_details.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "libpq/pqformat.h"
 #include "utils/array.h"
+#include "utils/arrayaccess.h"
 #include "utils/builtins.h"
 #include "utils/datum.h"
 #include "utils/lsyscache.h"
@@ -42,6 +46,12 @@ bool		Array_nulls = true;
  */
 #define ASSGN	 "="
 
+#define AARR_FREE_IF_COPY(array,n) \
+	do { \
+		if (!VARATT_IS_EXPANDED_HEADER(array)) \
+			PG_FREE_IF_COPY(array, n); \
+	} while (0)
+
 typedef enum
 {
 	ARRAY_NO_LEVEL,
@@ -93,10 +103,16 @@ static void ReadArrayBinary(StringInfo buf, int nitems,
 				int typlen, bool typbyval, char typalign,
 				Datum *values, bool *nulls,
 				bool *hasnulls, int32 *nbytes);
-static void CopyArrayEls(ArrayType *array,
-			 Datum *values, bool *nulls, int nitems,
-			 int typlen, bool typbyval, char typalign,
-			 bool freedata);
+static Datum array_get_element_expanded(Datum arraydatum,
+						   int nSubscripts, int *indx,
+						   int arraytyplen,
+						   int elmlen, bool elmbyval, char elmalign,
+						   bool *isNull);
+static Datum array_set_element_expanded(Datum arraydatum,
+						   int nSubscripts, int *indx,
+						   Datum dataValue, bool isNull,
+						   int arraytyplen,
+						   int elmlen, bool elmbyval, char elmalign);
 static bool array_get_isnull(const bits8 *nullbitmap, int offset);
 static void array_set_isnull(bits8 *nullbitmap, int offset, bool isNull);
 static Datum ArrayCast(char *value, bool byval, int len);
@@ -939,7 +955,7 @@ ReadArrayStr(char *arrayStr,
  * the values are not toasted.  (Doing it here doesn't work since the
  * caller has already allocated space for the array...)
  */
-static void
+void
 CopyArrayEls(ArrayType *array,
 			 Datum *values,
 			 bool *nulls,
@@ -997,8 +1013,8 @@ CopyArrayEls(ArrayType *array,
 Datum
 array_out(PG_FUNCTION_ARGS)
 {
-	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
-	Oid			element_type = ARR_ELEMTYPE(v);
+	AnyArrayType *v = PG_GETARG_ANY_ARRAY(0);
+	Oid			element_type = AARR_ELEMTYPE(v);
 	int			typlen;
 	bool		typbyval;
 	char		typalign;
@@ -1014,8 +1030,6 @@ array_out(PG_FUNCTION_ARGS)
 	 *
 	 * +2 allows for assignment operator + trailing null
 	 */
-	bits8	   *bitmap;
-	int			bitmask;
 	bool	   *needquotes,
 				needdims = false;
 	int			nitems,
@@ -1027,6 +1041,7 @@ array_out(PG_FUNCTION_ARGS)
 	int			ndim,
 			   *dims,
 			   *lb;
+	array_iter	iter;
 	ArrayMetaState *my_extra;
 
 	/*
@@ -1061,9 +1076,9 @@ array_out(PG_FUNCTION_ARGS)
 	typalign = my_extra->typalign;
 	typdelim = my_extra->typdelim;
 
-	ndim = ARR_NDIM(v);
-	dims = ARR_DIMS(v);
-	lb = ARR_LBOUND(v);
+	ndim = AARR_NDIM(v);
+	dims = AARR_DIMS(v);
+	lb = AARR_LBOUND(v);
 	nitems = ArrayGetNItems(ndim, dims);
 
 	if (nitems == 0)
@@ -1094,16 +1109,19 @@ array_out(PG_FUNCTION_ARGS)
 	needquotes = (bool *) palloc(nitems * sizeof(bool));
 	overall_length = 1;			/* don't forget to count \0 at end. */
 
-	p = ARR_DATA_PTR(v);
-	bitmap = ARR_NULLBITMAP(v);
-	bitmask = 1;
+	array_iter_setup(&iter, v);
 
 	for (i = 0; i < nitems; i++)
 	{
+		Datum		itemvalue;
+		bool		isnull;
 		bool		needquote;
 
 		/* Get source element, checking for NULL */
-		if (bitmap && (*bitmap & bitmask) == 0)
+		itemvalue = array_iter_next(&iter, &isnull, i,
+									typlen, typbyval, typalign);
+
+		if (isnull)
 		{
 			values[i] = pstrdup("NULL");
 			overall_length += 4;
@@ -1111,12 +1129,7 @@ array_out(PG_FUNCTION_ARGS)
 		}
 		else
 		{
-			Datum		itemvalue;
-
-			itemvalue = fetch_att(p, typbyval, typlen);
 			values[i] = OutputFunctionCall(&my_extra->proc, itemvalue);
-			p = att_addlength_pointer(p, typlen, p);
-			p = (char *) att_align_nominal(p, typalign);
 
 			/* count data plus backslashes; detect chars needing quotes */
 			if (values[i][0] == '\0')
@@ -1149,17 +1162,6 @@ array_out(PG_FUNCTION_ARGS)
 			overall_length += 2;
 		/* and the comma */
 		overall_length += 1;
-
-		/* advance bitmap pointer if any */
-		if (bitmap)
-		{
-			bitmask <<= 1;
-			if (bitmask == 0x100)
-			{
-				bitmap++;
-				bitmask = 1;
-			}
-		}
 	}
 
 	/*
@@ -1534,19 +1536,18 @@ ReadArrayBinary(StringInfo buf,
 Datum
 array_send(PG_FUNCTION_ARGS)
 {
-	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
-	Oid			element_type = ARR_ELEMTYPE(v);
+	AnyArrayType *v = PG_GETARG_ANY_ARRAY(0);
+	Oid			element_type = AARR_ELEMTYPE(v);
 	int			typlen;
 	bool		typbyval;
 	char		typalign;
-	char	   *p;
-	bits8	   *bitmap;
-	int			bitmask;
 	int			nitems,
 				i;
 	int			ndim,
-			   *dim;
+			   *dim,
+			   *lb;
 	StringInfoData buf;
+	array_iter	iter;
 	ArrayMetaState *my_extra;
 
 	/*
@@ -1583,60 +1584,49 @@ array_send(PG_FUNCTION_ARGS)
 	typbyval = my_extra->typbyval;
 	typalign = my_extra->typalign;
 
-	ndim = ARR_NDIM(v);
-	dim = ARR_DIMS(v);
+	ndim = AARR_NDIM(v);
+	dim = AARR_DIMS(v);
+	lb = AARR_LBOUND(v);
 	nitems = ArrayGetNItems(ndim, dim);
 
 	pq_begintypsend(&buf);
 
 	/* Send the array header information */
 	pq_sendint(&buf, ndim, 4);
-	pq_sendint(&buf, ARR_HASNULL(v) ? 1 : 0, 4);
+	pq_sendint(&buf, AARR_HASNULL(v) ? 1 : 0, 4);
 	pq_sendint(&buf, element_type, sizeof(Oid));
 	for (i = 0; i < ndim; i++)
 	{
-		pq_sendint(&buf, ARR_DIMS(v)[i], 4);
-		pq_sendint(&buf, ARR_LBOUND(v)[i], 4);
+		pq_sendint(&buf, dim[i], 4);
+		pq_sendint(&buf, lb[i], 4);
 	}
 
 	/* Send the array elements using the element's own sendproc */
-	p = ARR_DATA_PTR(v);
-	bitmap = ARR_NULLBITMAP(v);
-	bitmask = 1;
+	array_iter_setup(&iter, v);
 
 	for (i = 0; i < nitems; i++)
 	{
+		Datum		itemvalue;
+		bool		isnull;
+
 		/* Get source element, checking for NULL */
-		if (bitmap && (*bitmap & bitmask) == 0)
+		itemvalue = array_iter_next(&iter, &isnull, i,
+									typlen, typbyval, typalign);
+
+		if (isnull)
 		{
 			/* -1 length means a NULL */
 			pq_sendint(&buf, -1, 4);
 		}
 		else
 		{
-			Datum		itemvalue;
 			bytea	   *outputbytes;
 
-			itemvalue = fetch_att(p, typbyval, typlen);
 			outputbytes = SendFunctionCall(&my_extra->proc, itemvalue);
 			pq_sendint(&buf, VARSIZE(outputbytes) - VARHDRSZ, 4);
 			pq_sendbytes(&buf, VARDATA(outputbytes),
 						 VARSIZE(outputbytes) - VARHDRSZ);
 			pfree(outputbytes);
-
-			p = att_addlength_pointer(p, typlen, p);
-			p = (char *) att_align_nominal(p, typalign);
-		}
-
-		/* advance bitmap pointer if any */
-		if (bitmap)
-		{
-			bitmask <<= 1;
-			if (bitmask == 0x100)
-			{
-				bitmap++;
-				bitmask = 1;
-			}
 		}
 	}
 
@@ -1650,13 +1640,13 @@ array_send(PG_FUNCTION_ARGS)
 Datum
 array_ndims(PG_FUNCTION_ARGS)
 {
-	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
+	AnyArrayType *v = PG_GETARG_ANY_ARRAY(0);
 
 	/* Sanity check: does it look like an array at all? */
-	if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
+	if (AARR_NDIM(v) <= 0 || AARR_NDIM(v) > MAXDIM)
 		PG_RETURN_NULL();
 
-	PG_RETURN_INT32(ARR_NDIM(v));
+	PG_RETURN_INT32(AARR_NDIM(v));
 }
 
 /*
@@ -1666,7 +1656,7 @@ array_ndims(PG_FUNCTION_ARGS)
 Datum
 array_dims(PG_FUNCTION_ARGS)
 {
-	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
+	AnyArrayType *v = PG_GETARG_ANY_ARRAY(0);
 	char	   *p;
 	int			i;
 	int		   *dimv,
@@ -1680,14 +1670,14 @@ array_dims(PG_FUNCTION_ARGS)
 	char		buf[MAXDIM * 33 + 1];
 
 	/* Sanity check: does it look like an array at all? */
-	if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
+	if (AARR_NDIM(v) <= 0 || AARR_NDIM(v) > MAXDIM)
 		PG_RETURN_NULL();
 
-	dimv = ARR_DIMS(v);
-	lb = ARR_LBOUND(v);
+	dimv = AARR_DIMS(v);
+	lb = AARR_LBOUND(v);
 
 	p = buf;
-	for (i = 0; i < ARR_NDIM(v); i++)
+	for (i = 0; i < AARR_NDIM(v); i++)
 	{
 		sprintf(p, "[%d:%d]", lb[i], dimv[i] + lb[i] - 1);
 		p += strlen(p);
@@ -1704,20 +1694,20 @@ array_dims(PG_FUNCTION_ARGS)
 Datum
 array_lower(PG_FUNCTION_ARGS)
 {
-	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
+	AnyArrayType *v = PG_GETARG_ANY_ARRAY(0);
 	int			reqdim = PG_GETARG_INT32(1);
 	int		   *lb;
 	int			result;
 
 	/* Sanity check: does it look like an array at all? */
-	if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
+	if (AARR_NDIM(v) <= 0 || AARR_NDIM(v) > MAXDIM)
 		PG_RETURN_NULL();
 
 	/* Sanity check: was the requested dim valid */
-	if (reqdim <= 0 || reqdim > ARR_NDIM(v))
+	if (reqdim <= 0 || reqdim > AARR_NDIM(v))
 		PG_RETURN_NULL();
 
-	lb = ARR_LBOUND(v);
+	lb = AARR_LBOUND(v);
 	result = lb[reqdim - 1];
 
 	PG_RETURN_INT32(result);
@@ -1731,22 +1721,22 @@ array_lower(PG_FUNCTION_ARGS)
 Datum
 array_upper(PG_FUNCTION_ARGS)
 {
-	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
+	AnyArrayType *v = PG_GETARG_ANY_ARRAY(0);
 	int			reqdim = PG_GETARG_INT32(1);
 	int		   *dimv,
 			   *lb;
 	int			result;
 
 	/* Sanity check: does it look like an array at all? */
-	if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
+	if (AARR_NDIM(v) <= 0 || AARR_NDIM(v) > MAXDIM)
 		PG_RETURN_NULL();
 
 	/* Sanity check: was the requested dim valid */
-	if (reqdim <= 0 || reqdim > ARR_NDIM(v))
+	if (reqdim <= 0 || reqdim > AARR_NDIM(v))
 		PG_RETURN_NULL();
 
-	lb = ARR_LBOUND(v);
-	dimv = ARR_DIMS(v);
+	lb = AARR_LBOUND(v);
+	dimv = AARR_DIMS(v);
 
 	result = dimv[reqdim - 1] + lb[reqdim - 1] - 1;
 
@@ -1761,20 +1751,20 @@ array_upper(PG_FUNCTION_ARGS)
 Datum
 array_length(PG_FUNCTION_ARGS)
 {
-	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
+	AnyArrayType *v = PG_GETARG_ANY_ARRAY(0);
 	int			reqdim = PG_GETARG_INT32(1);
 	int		   *dimv;
 	int			result;
 
 	/* Sanity check: does it look like an array at all? */
-	if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
+	if (AARR_NDIM(v) <= 0 || AARR_NDIM(v) > MAXDIM)
 		PG_RETURN_NULL();
 
 	/* Sanity check: was the requested dim valid */
-	if (reqdim <= 0 || reqdim > ARR_NDIM(v))
+	if (reqdim <= 0 || reqdim > AARR_NDIM(v))
 		PG_RETURN_NULL();
 
-	dimv = ARR_DIMS(v);
+	dimv = AARR_DIMS(v);
 
 	result = dimv[reqdim - 1];
 
@@ -1788,9 +1778,9 @@ array_length(PG_FUNCTION_ARGS)
 Datum
 array_cardinality(PG_FUNCTION_ARGS)
 {
-	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
+	AnyArrayType *v = PG_GETARG_ANY_ARRAY(0);
 
-	PG_RETURN_INT32(ArrayGetNItems(ARR_NDIM(v), ARR_DIMS(v)));
+	PG_RETURN_INT32(ArrayGetNItems(AARR_NDIM(v), AARR_DIMS(v)));
 }
 
 
@@ -1825,7 +1815,6 @@ array_get_element(Datum arraydatum,
 				  char elmalign,
 				  bool *isNull)
 {
-	ArrayType  *array;
 	int			i,
 				ndim,
 			   *dim,
@@ -1850,10 +1839,22 @@ array_get_element(Datum arraydatum,
 		arraydataptr = (char *) DatumGetPointer(arraydatum);
 		arraynullsptr = NULL;
 	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(DatumGetPointer(arraydatum)))
+	{
+		/* expanded array: let's do this in a separate function */
+		return array_get_element_expanded(arraydatum,
+										  nSubscripts,
+										  indx,
+										  arraytyplen,
+										  elmlen,
+										  elmbyval,
+										  elmalign,
+										  isNull);
+	}
 	else
 	{
-		/* detoast input array if necessary */
-		array = DatumGetArrayTypeP(arraydatum);
+		/* detoast array if necessary, producing normal varlena input */
+		ArrayType  *array = DatumGetArrayTypeP(arraydatum);
 
 		ndim = ARR_NDIM(array);
 		dim = ARR_DIMS(array);
@@ -1903,6 +1904,88 @@ array_get_element(Datum arraydatum,
 }
 
 /*
+ * Implementation of array_get_element() for an expanded array
+ */
+static Datum
+array_get_element_expanded(Datum arraydatum,
+						   int nSubscripts, int *indx,
+						   int arraytyplen,
+						   int elmlen, bool elmbyval, char elmalign,
+						   bool *isNull)
+{
+	ExpandedArrayHeader *eah;
+	int			i,
+				ndim,
+			   *dim,
+			   *lb,
+				offset;
+	Datum	   *dvalues;
+	bool	   *dnulls;
+
+	eah = (ExpandedArrayHeader *) DatumGetEOHP(arraydatum);
+	Assert(eah->ea_magic == EA_MAGIC);
+
+	/* sanity-check caller's info against object */
+	Assert(arraytyplen == -1);
+	Assert(elmlen == eah->typlen);
+	Assert(elmbyval == eah->typbyval);
+	Assert(elmalign == eah->typalign);
+
+	ndim = eah->ndims;
+	dim = eah->dims;
+	lb = eah->lbound;
+
+	/*
+	 * Return NULL for invalid subscript
+	 */
+	if (ndim != nSubscripts || ndim <= 0 || ndim > MAXDIM)
+	{
+		*isNull = true;
+		return (Datum) 0;
+	}
+	for (i = 0; i < ndim; i++)
+	{
+		if (indx[i] < lb[i] || indx[i] >= (dim[i] + lb[i]))
+		{
+			*isNull = true;
+			return (Datum) 0;
+		}
+	}
+
+	/*
+	 * Calculate the element number
+	 */
+	offset = ArrayGetOffset(nSubscripts, dim, lb, indx);
+
+	/*
+	 * Deconstruct array if we didn't already.  Note that we apply this even
+	 * if the input is nominally read-only: it should be safe enough.
+	 */
+	deconstruct_expanded_array(eah);
+
+	dvalues = eah->dvalues;
+	dnulls = eah->dnulls;
+
+	/*
+	 * Check for NULL array element
+	 */
+	if (dnulls && dnulls[offset])
+	{
+		*isNull = true;
+		return (Datum) 0;
+	}
+
+	/*
+	 * OK, get the element.  It's OK to return a pass-by-ref value as a
+	 * pointer into the expanded array, for the same reason that regular
+	 * array_get_element can return a pointer into flat arrays: the value is
+	 * assumed not to change for as long as the Datum reference can exist.
+	 */
+	*isNull = false;
+	return dvalues[offset];
+}
+
+/*
  * array_get_slice :
  *		   This routine takes an array and a range of indices (upperIndex and
  *		   lowerIndx), creates a new array structure for the referred elements
@@ -2083,7 +2166,9 @@ array_get_slice(Datum arraydatum,
  *
  * Result:
  *		  A new array is returned, just like the old except for the one
- *		  modified entry.  The original array object is not changed.
+ *		  modified entry.  The original array object is not changed,
+ *		  unless what is passed is a read-write reference to an expanded
+ *		  array object; in that case the expanded array is updated in-place.
  *
  * For one-dimensional arrays only, we allow the array to be extended
  * by assigning to a position outside the existing subscript range; any
@@ -2166,6 +2251,20 @@ array_set_element(Datum arraydatum,
 	if (elmlen == -1 && !isNull)
 		dataValue = PointerGetDatum(PG_DETOAST_DATUM(dataValue));
 
+	if (VARATT_IS_EXTERNAL_EXPANDED(DatumGetPointer(arraydatum)))
+	{
+		/* expanded array: let's do this in a separate function */
+		return array_set_element_expanded(arraydatum,
+										  nSubscripts,
+										  indx,
+										  dataValue,
+										  isNull,
+										  arraytyplen,
+										  elmlen,
+										  elmbyval,
+										  elmalign);
+	}
+
 	/* detoast input array if necessary */
 	array = DatumGetArrayTypeP(arraydatum);
 
@@ -2355,6 +2454,251 @@ array_set_element(Datum arraydatum,
 }
 
 /*
+ * Implementation of array_set_element() for an expanded array
+ *
+ * Note: as with any operation on a read/write expanded object, we must
+ * take pains not to leave the object in a corrupt state if we fail partway
+ * through.
+ */
+static Datum
+array_set_element_expanded(Datum arraydatum,
+						   int nSubscripts, int *indx,
+						   Datum dataValue, bool isNull,
+						   int arraytyplen,
+						   int elmlen, bool elmbyval, char elmalign)
+{
+	ExpandedArrayHeader *eah;
+	Datum	   *dvalues;
+	bool	   *dnulls;
+	int			i,
+				ndim,
+				dim[MAXDIM],
+				lb[MAXDIM],
+				offset;
+	bool		dimschanged,
+				newhasnulls;
+	int			addedbefore,
+				addedafter;
+	char	   *oldValue;
+
+	/* Convert to R/W object if not so already */
+	eah = DatumGetExpandedArray(arraydatum);
+
+	/* Sanity-check caller's info against object; we don't use it otherwise */
+	Assert(arraytyplen == -1);
+	Assert(elmlen == eah->typlen);
+	Assert(elmbyval == eah->typbyval);
+	Assert(elmalign == eah->typalign);
+
+	/*
+	 * Copy dimension info into local storage.  This allows us to modify the
+	 * dimensions if needed, while not messing up the expanded value if we
+	 * fail partway through.
+	 */
+	ndim = eah->ndims;
+	Assert(ndim >= 0 && ndim <= MAXDIM);
+	memcpy(dim, eah->dims, ndim * sizeof(int));
+	memcpy(lb, eah->lbound, ndim * sizeof(int));
+	dimschanged = false;
+
+	/*
+	 * if number of dims is zero, i.e. an empty array, create an array with
+	 * nSubscripts dimensions, and set the lower bounds to the supplied
+	 * subscripts.
+	 */
+	if (ndim == 0)
+	{
+		/*
+		 * Allocate adequate space for new dimension info.  This is harmless
+		 * if we fail later.
+		 */
+		Assert(nSubscripts > 0 && nSubscripts <= MAXDIM);
+		eah->dims = (int *) MemoryContextAllocZero(eah->hdr.eoh_context,
+												   nSubscripts * sizeof(int));
+		eah->lbound = (int *) MemoryContextAllocZero(eah->hdr.eoh_context,
+												  nSubscripts * sizeof(int));
+
+		/* Update local copies of dimension info */
+		ndim = nSubscripts;
+		for (i = 0; i < nSubscripts; i++)
+		{
+			dim[i] = 0;
+			lb[i] = indx[i];
+		}
+		dimschanged = true;
+	}
+	else if (ndim != nSubscripts)
+		ereport(ERROR,
+				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
+				 errmsg("wrong number of array subscripts")));
+
+	/*
+	 * Deconstruct array if we didn't already.  (Someday maybe add a special
+	 * case path for fixed-length, no-nulls cases, where we can overwrite an
+	 * element in place without ever deconstructing.  But today is not that
+	 * day.)
+	 */
+	deconstruct_expanded_array(eah);
+
+	/*
+	 * Copy new element into array's context, if needed (we assume it's
+	 * already detoasted, so no junk should be created).  If we fail further
+	 * down, this memory is leaked, but that's reasonably harmless.
+	 */
+	if (!eah->typbyval && !isNull)
+	{
+		MemoryContext oldcxt = MemoryContextSwitchTo(eah->hdr.eoh_context);
+
+		dataValue = datumCopy(dataValue, false, eah->typlen);
+		MemoryContextSwitchTo(oldcxt);
+	}
+
+	dvalues = eah->dvalues;
+	dnulls = eah->dnulls;
+
+	newhasnulls = ((dnulls != NULL) || isNull);
+	addedbefore = addedafter = 0;
+
+	/*
+	 * Check subscripts (this logic matches original array_set_element)
+	 */
+	if (ndim == 1)
+	{
+		if (indx[0] < lb[0])
+		{
+			addedbefore = lb[0] - indx[0];
+			dim[0] += addedbefore;
+			lb[0] = indx[0];
+			dimschanged = true;
+			if (addedbefore > 1)
+				newhasnulls = true;		/* will insert nulls */
+		}
+		if (indx[0] >= (dim[0] + lb[0]))
+		{
+			addedafter = indx[0] - (dim[0] + lb[0]) + 1;
+			dim[0] += addedafter;
+			dimschanged = true;
+			if (addedafter > 1)
+				newhasnulls = true;		/* will insert nulls */
+		}
+	}
+	else
+	{
+		/*
+		 * XXX currently we do not support extending multi-dimensional arrays
+		 * during assignment
+		 */
+		for (i = 0; i < ndim; i++)
+		{
+			if (indx[i] < lb[i] ||
+				indx[i] >= (dim[i] + lb[i]))
+				ereport(ERROR,
+						(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
+						 errmsg("array subscript out of range")));
+		}
+	}
+
+	/* Now we can calculate linear offset of target item in array */
+	offset = ArrayGetOffset(nSubscripts, dim, lb, indx);
+
+	/* Physically enlarge existing dvalues/dnulls arrays if needed */
+	if (dim[0] > eah->dvalueslen)
+	{
+		/* We want some extra space if we're enlarging */
+		int			newlen = dim[0] + dim[0] / 8;
+
+		newlen = Max(newlen, dim[0]);	/* integer overflow guard */
+		eah->dvalues = dvalues = (Datum *)
+			repalloc(dvalues, newlen * sizeof(Datum));
+		if (dnulls)
+			eah->dnulls = dnulls = (bool *)
+				repalloc(dnulls, newlen * sizeof(bool));
+		eah->dvalueslen = newlen;
+	}
+
+	/*
+	 * If we need a nulls bitmap and don't already have one, create it, being
+	 * sure to mark all existing entries as not null.
+	 */
+	if (newhasnulls && dnulls == NULL)
+		eah->dnulls = dnulls = (bool *)
+			MemoryContextAllocZero(eah->hdr.eoh_context,
+								   eah->dvalueslen * sizeof(bool));
+
+	/*
+	 * We now have all the needed space allocated, so we're ready to make
+	 * irreversible changes.  Be very wary of allowing failure below here.
+	 */
+
+	/* Flattened value will no longer represent array accurately */
+	eah->fvalue = NULL;
+	/* And we don't know the flattened size either */
+	eah->flat_size = 0;
+
+	/* Update dimensionality info if needed */
+	if (dimschanged)
+	{
+		eah->ndims = ndim;
+		memcpy(eah->dims, dim, ndim * sizeof(int));
+		memcpy(eah->lbound, lb, ndim * sizeof(int));
+	}
+
+	/* Reposition items if needed, and fill addedbefore items with nulls */
+	if (addedbefore > 0)
+	{
+		memmove(dvalues + addedbefore, dvalues, eah->nelems * sizeof(Datum));
+		for (i = 0; i < addedbefore; i++)
+			dvalues[i] = (Datum) 0;
+		if (dnulls)
+		{
+			memmove(dnulls + addedbefore, dnulls, eah->nelems * sizeof(bool));
+			for (i = 0; i < addedbefore; i++)
+				dnulls[i] = true;
+		}
+		eah->nelems += addedbefore;
+	}
+
+	/* fill addedafter items with nulls */
+	if (addedafter > 0)
+	{
+		for (i = 0; i < addedafter; i++)
+			dvalues[eah->nelems + i] = (Datum) 0;
+		if (dnulls)
+		{
+			for (i = 0; i < addedafter; i++)
+				dnulls[eah->nelems + i] = true;
+		}
+		eah->nelems += addedafter;
+	}
+
+	/* Grab old element value for pfree'ing, if needed. */
+	if (!eah->typbyval && (dnulls == NULL || !dnulls[offset]))
+		oldValue = (char *) DatumGetPointer(dvalues[offset]);
+	else
+		oldValue = NULL;
+
+	/* And finally we can insert the new element. */
+	dvalues[offset] = dataValue;
+	if (dnulls)
+		dnulls[offset] = isNull;
+
+	/*
+	 * Free old element if needed; this keeps repeated element replacements
+	 * from bloating the array's storage.  If the pfree somehow fails, it
+	 * won't corrupt the array.
+	 */
+	if (oldValue)
+	{
+		/* Don't try to pfree a part of the original flat array */
+		if (oldValue < eah->fstartptr || oldValue >= eah->fendptr)
+			pfree(oldValue);
+	}
+
+	/* Done, return standard TOAST pointer for object */
+	return EOHPGetRWDatum(&eah->hdr);
+}
+
+/*
  * array_set_slice :
  *		  This routine sets the value of a range of array locations (specified
  *		  by upper and lower subscript values) to new values passed as
@@ -2734,8 +3078,6 @@ array_set(ArrayType *array, int nSubscripts, int *indx,
  *	 the function fn(), and if nargs > 1 then argument positions after the
  *	 first must be preset to the additional values to be passed.  The
  *	 first argument position initially holds the input array value.
- * * inpType: OID of element type of input array.  This must be the same as,
- *	 or binary-compatible with, the first argument type of fn().
  * * retType: OID of element type of output array.  This must be the same as,
  *	 or binary-compatible with, the result type of fn().
  * * amstate: workspace for array_map.  Must be zeroed by caller before
@@ -2749,14 +3091,12 @@ array_set(ArrayType *array, int nSubscripts, int *indx,
  * the array are OK however.
  */
 Datum
-array_map(FunctionCallInfo fcinfo, Oid inpType, Oid retType,
-		  ArrayMapState *amstate)
+array_map(FunctionCallInfo fcinfo, Oid retType, ArrayMapState *amstate)
 {
-	ArrayType  *v;
+	AnyArrayType *v;
 	ArrayType  *result;
 	Datum	   *values;
 	bool	   *nulls;
-	Datum		elt;
 	int		   *dim;
 	int			ndim;
 	int			nitems;
@@ -2764,15 +3104,14 @@ array_map(FunctionCallInfo fcinfo, Oid inpType, Oid retType,
 	int32		nbytes = 0;
 	int32		dataoffset;
 	bool		hasnulls;
+	Oid			inpType;
 	int			inp_typlen;
 	bool		inp_typbyval;
 	char		inp_typalign;
 	int			typlen;
 	bool		typbyval;
 	char		typalign;
-	char	   *s;
-	bits8	   *bitmap;
-	int			bitmask;
+	array_iter	iter;
 	ArrayMetaState *inp_extra;
 	ArrayMetaState *ret_extra;
 
@@ -2781,12 +3120,11 @@ array_map(FunctionCallInfo fcinfo, Oid inpType, Oid retType,
 		elog(ERROR, "invalid nargs: %d", fcinfo->nargs);
 	if (PG_ARGISNULL(0))
 		elog(ERROR, "null input array");
-	v = PG_GETARG_ARRAYTYPE_P(0);
-
-	Assert(ARR_ELEMTYPE(v) == inpType);
+	v = PG_GETARG_ANY_ARRAY(0);
 
-	ndim = ARR_NDIM(v);
-	dim = ARR_DIMS(v);
+	inpType = AARR_ELEMTYPE(v);
+	ndim = AARR_NDIM(v);
+	dim = AARR_DIMS(v);
 	nitems = ArrayGetNItems(ndim, dim);
 
 	/* Check for empty array */
@@ -2833,9 +3171,7 @@ array_map(FunctionCallInfo fcinfo, Oid inpType, Oid retType,
 	nulls = (bool *) palloc(nitems * sizeof(bool));
 
 	/* Loop over source data */
-	s = ARR_DATA_PTR(v);
-	bitmap = ARR_NULLBITMAP(v);
-	bitmask = 1;
+	array_iter_setup(&iter, v);
 	hasnulls = false;
 
 	for (i = 0; i < nitems; i++)
@@ -2843,18 +3179,8 @@ array_map(FunctionCallInfo fcinfo, Oid inpType, Oid retType,
 		bool		callit = true;
 
 		/* Get source element, checking for NULL */
-		if (bitmap && (*bitmap & bitmask) == 0)
-		{
-			fcinfo->argnull[0] = true;
-		}
-		else
-		{
-			elt = fetch_att(s, inp_typbyval, inp_typlen);
-			s = att_addlength_datum(s, inp_typlen, elt);
-			s = (char *) att_align_nominal(s, inp_typalign);
-			fcinfo->arg[0] = elt;
-			fcinfo->argnull[0] = false;
-		}
+		fcinfo->arg[0] = array_iter_next(&iter, &fcinfo->argnull[0], i,
+									 inp_typlen, inp_typbyval, inp_typalign);
 
 		/*
 		 * Apply the given function to source elt and extra args.
@@ -2899,17 +3225,6 @@ array_map(FunctionCallInfo fcinfo, Oid inpType, Oid retType,
 						 errmsg("array size exceeds the maximum allowed (%d)",
 								(int) MaxAllocSize)));
 		}
-
-		/* advance bitmap pointer if any */
-		if (bitmap)
-		{
-			bitmask <<= 1;
-			if (bitmask == 0x100)
-			{
-				bitmap++;
-				bitmask = 1;
-			}
-		}
 	}
 
 	/* Allocate and initialize the result array */
@@ -2928,7 +3243,8 @@ array_map(FunctionCallInfo fcinfo, Oid inpType, Oid retType,
 	result->ndim = ndim;
 	result->dataoffset = dataoffset;
 	result->elemtype = retType;
-	memcpy(ARR_DIMS(result), ARR_DIMS(v), 2 * ndim * sizeof(int));
+	memcpy(ARR_DIMS(result), AARR_DIMS(v), ndim * sizeof(int));
+	memcpy(ARR_LBOUND(result), AARR_LBOUND(v), ndim * sizeof(int));
 
 	/*
 	 * Note: do not risk trying to pfree the results of the called function
@@ -3092,6 +3408,23 @@ construct_empty_array(Oid elmtype)
 }
 
 /*
+ * construct_empty_expanded_array: make an empty expanded array
+ * given only type information.  (metacache can be NULL if not needed.)
+ */
+ExpandedArrayHeader *
+construct_empty_expanded_array(Oid element_type,
+							   MemoryContext parentcontext,
+							   ArrayMetaState *metacache)
+{
+	ArrayType  *array = construct_empty_array(element_type);
+	Datum		d;
+
+	d = expand_array(PointerGetDatum(array), parentcontext, metacache);
+	pfree(array);
+	return (ExpandedArrayHeader *) DatumGetEOHP(d);
+}
+
+/*
  * deconstruct_array  --- simple method for extracting data from an array
  *
  * array: array object to examine (must not be NULL)
@@ -3229,36 +3562,36 @@ array_contains_nulls(ArrayType *array)
 Datum
 array_eq(PG_FUNCTION_ARGS)
 {
-	ArrayType  *array1 = PG_GETARG_ARRAYTYPE_P(0);
-	ArrayType  *array2 = PG_GETARG_ARRAYTYPE_P(1);
+	AnyArrayType *array1 = PG_GETARG_ANY_ARRAY(0);
+	AnyArrayType *array2 = PG_GETARG_ANY_ARRAY(1);
 	Oid			collation = PG_GET_COLLATION();
-	int			ndims1 = ARR_NDIM(array1);
-	int			ndims2 = ARR_NDIM(array2);
-	int		   *dims1 = ARR_DIMS(array1);
-	int		   *dims2 = ARR_DIMS(array2);
-	Oid			element_type = ARR_ELEMTYPE(array1);
+	int			ndims1 = AARR_NDIM(array1);
+	int			ndims2 = AARR_NDIM(array2);
+	int		   *dims1 = AARR_DIMS(array1);
+	int		   *dims2 = AARR_DIMS(array2);
+	int		   *lbs1 = AARR_LBOUND(array1);
+	int		   *lbs2 = AARR_LBOUND(array2);
+	Oid			element_type = AARR_ELEMTYPE(array1);
 	bool		result = true;
 	int			nitems;
 	TypeCacheEntry *typentry;
 	int			typlen;
 	bool		typbyval;
 	char		typalign;
-	char	   *ptr1;
-	char	   *ptr2;
-	bits8	   *bitmap1;
-	bits8	   *bitmap2;
-	int			bitmask;
+	array_iter	it1;
+	array_iter	it2;
 	int			i;
 	FunctionCallInfoData locfcinfo;
 
-	if (element_type != ARR_ELEMTYPE(array2))
+	if (element_type != AARR_ELEMTYPE(array2))
 		ereport(ERROR,
 				(errcode(ERRCODE_DATATYPE_MISMATCH),
 				 errmsg("cannot compare arrays of different element types")));
 
 	/* fast path if the arrays do not have the same dimensionality */
 	if (ndims1 != ndims2 ||
-		memcmp(dims1, dims2, 2 * ndims1 * sizeof(int)) != 0)
+		memcmp(dims1, dims2, ndims1 * sizeof(int)) != 0 ||
+		memcmp(lbs1, lbs2, ndims1 * sizeof(int)) != 0)
 		result = false;
 	else
 	{
@@ -3293,11 +3626,8 @@ array_eq(PG_FUNCTION_ARGS)
 
 		/* Loop over source data */
 		nitems = ArrayGetNItems(ndims1, dims1);
-		ptr1 = ARR_DATA_PTR(array1);
-		ptr2 = ARR_DATA_PTR(array2);
-		bitmap1 = ARR_NULLBITMAP(array1);
-		bitmap2 = ARR_NULLBITMAP(array2);
-		bitmask = 1;			/* use same bitmask for both arrays */
+		array_iter_setup(&it1, array1);
+		array_iter_setup(&it2, array2);
 
 		for (i = 0; i < nitems; i++)
 		{
@@ -3308,42 +3638,10 @@ array_eq(PG_FUNCTION_ARGS)
 			bool		oprresult;
 
 			/* Get elements, checking for NULL */
-			if (bitmap1 && (*bitmap1 & bitmask) == 0)
-			{
-				isnull1 = true;
-				elt1 = (Datum) 0;
-			}
-			else
-			{
-				isnull1 = false;
-				elt1 = fetch_att(ptr1, typbyval, typlen);
-				ptr1 = att_addlength_pointer(ptr1, typlen, ptr1);
-				ptr1 = (char *) att_align_nominal(ptr1, typalign);
-			}
-
-			if (bitmap2 && (*bitmap2 & bitmask) == 0)
-			{
-				isnull2 = true;
-				elt2 = (Datum) 0;
-			}
-			else
-			{
-				isnull2 = false;
-				elt2 = fetch_att(ptr2, typbyval, typlen);
-				ptr2 = att_addlength_pointer(ptr2, typlen, ptr2);
-				ptr2 = (char *) att_align_nominal(ptr2, typalign);
-			}
-
-			/* advance bitmap pointers if any */
-			bitmask <<= 1;
-			if (bitmask == 0x100)
-			{
-				if (bitmap1)
-					bitmap1++;
-				if (bitmap2)
-					bitmap2++;
-				bitmask = 1;
-			}
+			elt1 = array_iter_next(&it1, &isnull1, i,
+								   typlen, typbyval, typalign);
+			elt2 = array_iter_next(&it2, &isnull2, i,
+								   typlen, typbyval, typalign);
 
 			/*
 			 * We consider two NULLs equal; NULL and not-NULL are unequal.
@@ -3374,8 +3672,8 @@ array_eq(PG_FUNCTION_ARGS)
 	}
 
 	/* Avoid leaking memory when handed toasted input. */
-	PG_FREE_IF_COPY(array1, 0);
-	PG_FREE_IF_COPY(array2, 1);
+	AARR_FREE_IF_COPY(array1, 0);
+	AARR_FREE_IF_COPY(array2, 1);
 
 	PG_RETURN_BOOL(result);
 }
@@ -3435,31 +3733,28 @@ btarraycmp(PG_FUNCTION_ARGS)
 static int
 array_cmp(FunctionCallInfo fcinfo)
 {
-	ArrayType  *array1 = PG_GETARG_ARRAYTYPE_P(0);
-	ArrayType  *array2 = PG_GETARG_ARRAYTYPE_P(1);
+	AnyArrayType *array1 = PG_GETARG_ANY_ARRAY(0);
+	AnyArrayType *array2 = PG_GETARG_ANY_ARRAY(1);
 	Oid			collation = PG_GET_COLLATION();
-	int			ndims1 = ARR_NDIM(array1);
-	int			ndims2 = ARR_NDIM(array2);
-	int		   *dims1 = ARR_DIMS(array1);
-	int		   *dims2 = ARR_DIMS(array2);
+	int			ndims1 = AARR_NDIM(array1);
+	int			ndims2 = AARR_NDIM(array2);
+	int		   *dims1 = AARR_DIMS(array1);
+	int		   *dims2 = AARR_DIMS(array2);
 	int			nitems1 = ArrayGetNItems(ndims1, dims1);
 	int			nitems2 = ArrayGetNItems(ndims2, dims2);
-	Oid			element_type = ARR_ELEMTYPE(array1);
+	Oid			element_type = AARR_ELEMTYPE(array1);
 	int			result = 0;
 	TypeCacheEntry *typentry;
 	int			typlen;
 	bool		typbyval;
 	char		typalign;
 	int			min_nitems;
-	char	   *ptr1;
-	char	   *ptr2;
-	bits8	   *bitmap1;
-	bits8	   *bitmap2;
-	int			bitmask;
+	array_iter	it1;
+	array_iter	it2;
 	int			i;
 	FunctionCallInfoData locfcinfo;
 
-	if (element_type != ARR_ELEMTYPE(array2))
+	if (element_type != AARR_ELEMTYPE(array2))
 		ereport(ERROR,
 				(errcode(ERRCODE_DATATYPE_MISMATCH),
 				 errmsg("cannot compare arrays of different element types")));
@@ -3495,11 +3790,8 @@ array_cmp(FunctionCallInfo fcinfo)
 
 	/* Loop over source data */
 	min_nitems = Min(nitems1, nitems2);
-	ptr1 = ARR_DATA_PTR(array1);
-	ptr2 = ARR_DATA_PTR(array2);
-	bitmap1 = ARR_NULLBITMAP(array1);
-	bitmap2 = ARR_NULLBITMAP(array2);
-	bitmask = 1;				/* use same bitmask for both arrays */
+	array_iter_setup(&it1, array1);
+	array_iter_setup(&it2, array2);
 
 	for (i = 0; i < min_nitems; i++)
 	{
@@ -3510,42 +3802,8 @@ array_cmp(FunctionCallInfo fcinfo)
 		int32		cmpresult;
 
 		/* Get elements, checking for NULL */
-		if (bitmap1 && (*bitmap1 & bitmask) == 0)
-		{
-			isnull1 = true;
-			elt1 = (Datum) 0;
-		}
-		else
-		{
-			isnull1 = false;
-			elt1 = fetch_att(ptr1, typbyval, typlen);
-			ptr1 = att_addlength_pointer(ptr1, typlen, ptr1);
-			ptr1 = (char *) att_align_nominal(ptr1, typalign);
-		}
-
-		if (bitmap2 && (*bitmap2 & bitmask) == 0)
-		{
-			isnull2 = true;
-			elt2 = (Datum) 0;
-		}
-		else
-		{
-			isnull2 = false;
-			elt2 = fetch_att(ptr2, typbyval, typlen);
-			ptr2 = att_addlength_pointer(ptr2, typlen, ptr2);
-			ptr2 = (char *) att_align_nominal(ptr2, typalign);
-		}
-
-		/* advance bitmap pointers if any */
-		bitmask <<= 1;
-		if (bitmask == 0x100)
-		{
-			if (bitmap1)
-				bitmap1++;
-			if (bitmap2)
-				bitmap2++;
-			bitmask = 1;
-		}
+		elt1 = array_iter_next(&it1, &isnull1, i, typlen, typbyval, typalign);
+		elt2 = array_iter_next(&it2, &isnull2, i, typlen, typbyval, typalign);
 
 		/*
 		 * We consider two NULLs equal; NULL > not-NULL.
@@ -3604,8 +3862,7 @@ array_cmp(FunctionCallInfo fcinfo)
 			result = (ndims1 < ndims2) ? -1 : 1;
 		else
 		{
-			/* this relies on LB array immediately following DIMS array */
-			for (i = 0; i < ndims1 * 2; i++)
+			for (i = 0; i < ndims1; i++)
 			{
 				if (dims1[i] != dims2[i])
 				{
@@ -3613,12 +3870,26 @@ array_cmp(FunctionCallInfo fcinfo)
 					break;
 				}
 			}
+			if (result == 0)
+			{
+				int		   *lbound1 = AARR_LBOUND(array1);
+				int		   *lbound2 = AARR_LBOUND(array2);
+
+				for (i = 0; i < ndims1; i++)
+				{
+					if (lbound1[i] != lbound2[i])
+					{
+						result = (lbound1[i] < lbound2[i]) ? -1 : 1;
+						break;
+					}
+				}
+			}
 		}
 	}
 
 	/* Avoid leaking memory when handed toasted input. */
-	PG_FREE_IF_COPY(array1, 0);
-	PG_FREE_IF_COPY(array2, 1);
+	AARR_FREE_IF_COPY(array1, 0);
+	AARR_FREE_IF_COPY(array2, 1);
 
 	return result;
 }
@@ -3633,20 +3904,18 @@ array_cmp(FunctionCallInfo fcinfo)
 Datum
 hash_array(PG_FUNCTION_ARGS)
 {
-	ArrayType  *array = PG_GETARG_ARRAYTYPE_P(0);
-	int			ndims = ARR_NDIM(array);
-	int		   *dims = ARR_DIMS(array);
-	Oid			element_type = ARR_ELEMTYPE(array);
+	AnyArrayType *array = PG_GETARG_ANY_ARRAY(0);
+	int			ndims = AARR_NDIM(array);
+	int		   *dims = AARR_DIMS(array);
+	Oid			element_type = AARR_ELEMTYPE(array);
 	uint32		result = 1;
 	int			nitems;
 	TypeCacheEntry *typentry;
 	int			typlen;
 	bool		typbyval;
 	char		typalign;
-	char	   *ptr;
-	bits8	   *bitmap;
-	int			bitmask;
 	int			i;
+	array_iter	iter;
 	FunctionCallInfoData locfcinfo;
 
 	/*
@@ -3680,28 +3949,24 @@ hash_array(PG_FUNCTION_ARGS)
 
 	/* Loop over source data */
 	nitems = ArrayGetNItems(ndims, dims);
-	ptr = ARR_DATA_PTR(array);
-	bitmap = ARR_NULLBITMAP(array);
-	bitmask = 1;
+	array_iter_setup(&iter, array);
 
 	for (i = 0; i < nitems; i++)
 	{
+		Datum		elt;
+		bool		isnull;
 		uint32		elthash;
 
 		/* Get element, checking for NULL */
-		if (bitmap && (*bitmap & bitmask) == 0)
+		elt = array_iter_next(&iter, &isnull, i, typlen, typbyval, typalign);
+
+		if (isnull)
 		{
 			/* Treat nulls as having hashvalue 0 */
 			elthash = 0;
 		}
 		else
 		{
-			Datum		elt;
-
-			elt = fetch_att(ptr, typbyval, typlen);
-			ptr = att_addlength_pointer(ptr, typlen, ptr);
-			ptr = (char *) att_align_nominal(ptr, typalign);
-
 			/* Apply the hash function */
 			locfcinfo.arg[0] = elt;
 			locfcinfo.argnull[0] = false;
@@ -3709,17 +3974,6 @@ hash_array(PG_FUNCTION_ARGS)
 			elthash = DatumGetUInt32(FunctionCallInvoke(&locfcinfo));
 		}
 
-		/* advance bitmap pointer if any */
-		if (bitmap)
-		{
-			bitmask <<= 1;
-			if (bitmask == 0x100)
-			{
-				bitmap++;
-				bitmask = 1;
-			}
-		}
-
 		/*
 		 * Combine hash values of successive elements by multiplying the
 		 * current value by 31 and adding on the new element's hash value.
@@ -3735,7 +3989,7 @@ hash_array(PG_FUNCTION_ARGS)
 	}
 
 	/* Avoid leaking memory when handed toasted input. */
-	PG_FREE_IF_COPY(array, 0);
+	AARR_FREE_IF_COPY(array, 0);
 
 	PG_RETURN_UINT32(result);
 }
@@ -3756,11 +4010,11 @@ hash_array(PG_FUNCTION_ARGS)
  * When matchall is false, return true if any members of array1 are in array2.
  */
 static bool
-array_contain_compare(ArrayType *array1, ArrayType *array2, Oid collation,
+array_contain_compare(AnyArrayType *array1, AnyArrayType *array2, Oid collation,
 					  bool matchall, void **fn_extra)
 {
 	bool		result = matchall;
-	Oid			element_type = ARR_ELEMTYPE(array1);
+	Oid			element_type = AARR_ELEMTYPE(array1);
 	TypeCacheEntry *typentry;
 	int			nelems1;
 	Datum	   *values2;
@@ -3769,14 +4023,12 @@ array_contain_compare(ArrayType *array1, ArrayType *array2, Oid collation,
 	int			typlen;
 	bool		typbyval;
 	char		typalign;
-	char	   *ptr1;
-	bits8	   *bitmap1;
-	int			bitmask;
 	int			i;
 	int			j;
+	array_iter	it1;
 	FunctionCallInfoData locfcinfo;
 
-	if (element_type != ARR_ELEMTYPE(array2))
+	if (element_type != AARR_ELEMTYPE(array2))
 		ereport(ERROR,
 				(errcode(ERRCODE_DATATYPE_MISMATCH),
 				 errmsg("cannot compare arrays of different element types")));
@@ -3809,8 +4061,18 @@ array_contain_compare(ArrayType *array1, ArrayType *array2, Oid collation,
 	 * worthwhile to use deconstruct_array on it.  We scan array1 the hard way
 	 * however, since we very likely won't need to look at all of it.
 	 */
-	deconstruct_array(array2, element_type, typlen, typbyval, typalign,
-					  &values2, &nulls2, &nelems2);
+	if (VARATT_IS_EXPANDED_HEADER(array2))
+	{
+		/* This should be safe even if input is read-only */
+		deconstruct_expanded_array(&(array2->xpn));
+		values2 = array2->xpn.dvalues;
+		nulls2 = array2->xpn.dnulls;
+		nelems2 = array2->xpn.nelems;
+	}
+	else
+		deconstruct_array(&(array2->flt),
+						  element_type, typlen, typbyval, typalign,
+						  &values2, &nulls2, &nelems2);
 
 	/*
 	 * Apply the comparison operator to each pair of array elements.
@@ -3819,10 +4081,8 @@ array_contain_compare(ArrayType *array1, ArrayType *array2, Oid collation,
 							 collation, NULL, NULL);
 
 	/* Loop over source data */
-	nelems1 = ArrayGetNItems(ARR_NDIM(array1), ARR_DIMS(array1));
-	ptr1 = ARR_DATA_PTR(array1);
-	bitmap1 = ARR_NULLBITMAP(array1);
-	bitmask = 1;
+	nelems1 = ArrayGetNItems(AARR_NDIM(array1), AARR_DIMS(array1));
+	array_iter_setup(&it1, array1);
 
 	for (i = 0; i < nelems1; i++)
 	{
@@ -3830,27 +4090,7 @@ array_contain_compare(ArrayType *array1, ArrayType *array2, Oid collation,
 		bool		isnull1;
 
 		/* Get element, checking for NULL */
-		if (bitmap1 && (*bitmap1 & bitmask) == 0)
-		{
-			isnull1 = true;
-			elt1 = (Datum) 0;
-		}
-		else
-		{
-			isnull1 = false;
-			elt1 = fetch_att(ptr1, typbyval, typlen);
-			ptr1 = att_addlength_pointer(ptr1, typlen, ptr1);
-			ptr1 = (char *) att_align_nominal(ptr1, typalign);
-		}
-
-		/* advance bitmap pointer if any */
-		bitmask <<= 1;
-		if (bitmask == 0x100)
-		{
-			if (bitmap1)
-				bitmap1++;
-			bitmask = 1;
-		}
+		elt1 = array_iter_next(&it1, &isnull1, i, typlen, typbyval, typalign);
 
 		/*
 		 * We assume that the comparison operator is strict, so a NULL can't
@@ -3909,17 +4149,14 @@ array_contain_compare(ArrayType *array1, ArrayType *array2, Oid collation,
 		}
 	}
 
-	pfree(values2);
-	pfree(nulls2);
-
 	return result;
 }
 
 Datum
 arrayoverlap(PG_FUNCTION_ARGS)
 {
-	ArrayType  *array1 = PG_GETARG_ARRAYTYPE_P(0);
-	ArrayType  *array2 = PG_GETARG_ARRAYTYPE_P(1);
+	AnyArrayType *array1 = PG_GETARG_ANY_ARRAY(0);
+	AnyArrayType *array2 = PG_GETARG_ANY_ARRAY(1);
 	Oid			collation = PG_GET_COLLATION();
 	bool		result;
 
@@ -3927,8 +4164,8 @@ arrayoverlap(PG_FUNCTION_ARGS)
 								   &fcinfo->flinfo->fn_extra);
 
 	/* Avoid leaking memory when handed toasted input. */
-	PG_FREE_IF_COPY(array1, 0);
-	PG_FREE_IF_COPY(array2, 1);
+	AARR_FREE_IF_COPY(array1, 0);
+	AARR_FREE_IF_COPY(array2, 1);
 
 	PG_RETURN_BOOL(result);
 }
@@ -3936,8 +4173,8 @@ arrayoverlap(PG_FUNCTION_ARGS)
 Datum
 arraycontains(PG_FUNCTION_ARGS)
 {
-	ArrayType  *array1 = PG_GETARG_ARRAYTYPE_P(0);
-	ArrayType  *array2 = PG_GETARG_ARRAYTYPE_P(1);
+	AnyArrayType *array1 = PG_GETARG_ANY_ARRAY(0);
+	AnyArrayType *array2 = PG_GETARG_ANY_ARRAY(1);
 	Oid			collation = PG_GET_COLLATION();
 	bool		result;
 
@@ -3945,8 +4182,8 @@ arraycontains(PG_FUNCTION_ARGS)
 								   &fcinfo->flinfo->fn_extra);
 
 	/* Avoid leaking memory when handed toasted input. */
-	PG_FREE_IF_COPY(array1, 0);
-	PG_FREE_IF_COPY(array2, 1);
+	AARR_FREE_IF_COPY(array1, 0);
+	AARR_FREE_IF_COPY(array2, 1);
 
 	PG_RETURN_BOOL(result);
 }
@@ -3954,8 +4191,8 @@ arraycontains(PG_FUNCTION_ARGS)
 Datum
 arraycontained(PG_FUNCTION_ARGS)
 {
-	ArrayType  *array1 = PG_GETARG_ARRAYTYPE_P(0);
-	ArrayType  *array2 = PG_GETARG_ARRAYTYPE_P(1);
+	AnyArrayType *array1 = PG_GETARG_ANY_ARRAY(0);
+	AnyArrayType *array2 = PG_GETARG_ANY_ARRAY(1);
 	Oid			collation = PG_GET_COLLATION();
 	bool		result;
 
@@ -3963,8 +4200,8 @@ arraycontained(PG_FUNCTION_ARGS)
 								   &fcinfo->flinfo->fn_extra);
 
 	/* Avoid leaking memory when handed toasted input. */
-	PG_FREE_IF_COPY(array1, 0);
-	PG_FREE_IF_COPY(array2, 1);
+	AARR_FREE_IF_COPY(array1, 0);
+	AARR_FREE_IF_COPY(array2, 1);
 
 	PG_RETURN_BOOL(result);
 }
@@ -4702,7 +4939,8 @@ initArrayResult(Oid element_type, MemoryContext rcontext, bool subcontext)
 		MemoryContextAlloc(arr_context, sizeof(ArrayBuildState));
 	astate->mcontext = arr_context;
 	astate->private_cxt = subcontext;
-	astate->alen = (subcontext ? 64 : 8);	/* arbitrary starting array size */
+	astate->alen = (subcontext ? 64 : 8);		/* arbitrary starting array
+												 * size */
 	astate->dvalues = (Datum *)
 		MemoryContextAlloc(arr_context, astate->alen * sizeof(Datum));
 	astate->dnulls = (bool *)
@@ -4878,10 +5116,11 @@ initArrayResultArr(Oid array_type, Oid element_type, MemoryContext rcontext,
 				   bool subcontext)
 {
 	ArrayBuildStateArr *astate;
-	MemoryContext arr_context = rcontext;   /* by default use the parent ctx */
+	MemoryContext arr_context = rcontext;		/* by default use the parent
+												 * ctx */
 
 	/* Lookup element type, unless element_type already provided */
-	if (! OidIsValid(element_type))
+	if (!OidIsValid(element_type))
 	{
 		element_type = get_element_type(array_type);
 
@@ -5259,31 +5498,19 @@ makeArrayResultAny(ArrayBuildStateAny *astate,
 Datum
 array_larger(PG_FUNCTION_ARGS)
 {
-	ArrayType  *v1,
-			   *v2,
-			   *result;
-
-	v1 = PG_GETARG_ARRAYTYPE_P(0);
-	v2 = PG_GETARG_ARRAYTYPE_P(1);
-
-	result = ((array_cmp(fcinfo) > 0) ? v1 : v2);
-
-	PG_RETURN_ARRAYTYPE_P(result);
+	if (array_cmp(fcinfo) > 0)
+		PG_RETURN_DATUM(PG_GETARG_DATUM(0));
+	else
+		PG_RETURN_DATUM(PG_GETARG_DATUM(1));
 }
 
 Datum
 array_smaller(PG_FUNCTION_ARGS)
 {
-	ArrayType  *v1,
-			   *v2,
-			   *result;
-
-	v1 = PG_GETARG_ARRAYTYPE_P(0);
-	v2 = PG_GETARG_ARRAYTYPE_P(1);
-
-	result = ((array_cmp(fcinfo) < 0) ? v1 : v2);
-
-	PG_RETURN_ARRAYTYPE_P(result);
+	if (array_cmp(fcinfo) < 0)
+		PG_RETURN_DATUM(PG_GETARG_DATUM(0));
+	else
+		PG_RETURN_DATUM(PG_GETARG_DATUM(1));
 }
 
 
@@ -5308,7 +5535,7 @@ generate_subscripts(PG_FUNCTION_ARGS)
 	/* stuff done only on the first call of the function */
 	if (SRF_IS_FIRSTCALL())
 	{
-		ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
+		AnyArrayType *v = PG_GETARG_ANY_ARRAY(0);
 		int			reqdim = PG_GETARG_INT32(1);
 		int		   *lb,
 				   *dimv;
@@ -5317,11 +5544,11 @@ generate_subscripts(PG_FUNCTION_ARGS)
 		funcctx = SRF_FIRSTCALL_INIT();
 
 		/* Sanity check: does it look like an array at all? */
-		if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
+		if (AARR_NDIM(v) <= 0 || AARR_NDIM(v) > MAXDIM)
 			SRF_RETURN_DONE(funcctx);
 
 		/* Sanity check: was the requested dim valid */
-		if (reqdim <= 0 || reqdim > ARR_NDIM(v))
+		if (reqdim <= 0 || reqdim > AARR_NDIM(v))
 			SRF_RETURN_DONE(funcctx);
 
 		/*
@@ -5330,8 +5557,8 @@ generate_subscripts(PG_FUNCTION_ARGS)
 		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
 		fctx = (generate_subscripts_fctx *) palloc(sizeof(generate_subscripts_fctx));
 
-		lb = ARR_LBOUND(v);
-		dimv = ARR_DIMS(v);
+		lb = AARR_LBOUND(v);
+		dimv = AARR_DIMS(v);
 
 		fctx->lower = lb[reqdim - 1];
 		fctx->upper = dimv[reqdim - 1] + lb[reqdim - 1] - 1;
@@ -5650,11 +5877,9 @@ array_unnest(PG_FUNCTION_ARGS)
 {
 	typedef struct
 	{
-		ArrayType  *arr;
+		array_iter	iter;
 		int			nextelem;
 		int			numelems;
-		char	   *elemdataptr;	/* this moves with nextelem */
-		bits8	   *arraynullsptr;		/* this does not */
 		int16		elmlen;
 		bool		elmbyval;
 		char		elmalign;
@@ -5667,7 +5892,7 @@ array_unnest(PG_FUNCTION_ARGS)
 	/* stuff done only on the first call of the function */
 	if (SRF_IS_FIRSTCALL())
 	{
-		ArrayType  *arr;
+		AnyArrayType *arr;
 
 		/* create a function context for cross-call persistence */
 		funcctx = SRF_FIRSTCALL_INIT();
@@ -5684,23 +5909,28 @@ array_unnest(PG_FUNCTION_ARGS)
 		 * and not before.  (If no detoast happens, we assume the originally
 		 * passed array will stick around till then.)
 		 */
-		arr = PG_GETARG_ARRAYTYPE_P(0);
+		arr = PG_GETARG_ANY_ARRAY(0);
 
 		/* allocate memory for user context */
 		fctx = (array_unnest_fctx *) palloc(sizeof(array_unnest_fctx));
 
 		/* initialize state */
-		fctx->arr = arr;
+		array_iter_setup(&fctx->iter, arr);
 		fctx->nextelem = 0;
-		fctx->numelems = ArrayGetNItems(ARR_NDIM(arr), ARR_DIMS(arr));
-
-		fctx->elemdataptr = ARR_DATA_PTR(arr);
-		fctx->arraynullsptr = ARR_NULLBITMAP(arr);
+		fctx->numelems = ArrayGetNItems(AARR_NDIM(arr), AARR_DIMS(arr));
 
-		get_typlenbyvalalign(ARR_ELEMTYPE(arr),
-							 &fctx->elmlen,
-							 &fctx->elmbyval,
-							 &fctx->elmalign);
+		if (VARATT_IS_EXPANDED_HEADER(arr))
+		{
+			/* we can just grab the type data from expanded array */
+			fctx->elmlen = arr->xpn.typlen;
+			fctx->elmbyval = arr->xpn.typbyval;
+			fctx->elmalign = arr->xpn.typalign;
+		}
+		else
+			get_typlenbyvalalign(AARR_ELEMTYPE(arr),
+								 &fctx->elmlen,
+								 &fctx->elmbyval,
+								 &fctx->elmalign);
 
 		funcctx->user_fctx = fctx;
 		MemoryContextSwitchTo(oldcontext);
@@ -5715,32 +5945,8 @@ array_unnest(PG_FUNCTION_ARGS)
 		int			offset = fctx->nextelem++;
 		Datum		elem;
 
-		/*
-		 * Check for NULL array element
-		 */
-		if (array_get_isnull(fctx->arraynullsptr, offset))
-		{
-			fcinfo->isnull = true;
-			elem = (Datum) 0;
-			/* elemdataptr does not move */
-		}
-		else
-		{
-			/*
-			 * OK, get the element
-			 */
-			char	   *ptr = fctx->elemdataptr;
-
-			fcinfo->isnull = false;
-			elem = ArrayCast(ptr, fctx->elmbyval, fctx->elmlen);
-
-			/*
-			 * Advance elemdataptr over it
-			 */
-			ptr = att_addlength_pointer(ptr, fctx->elmlen, ptr);
-			ptr = (char *) att_align_nominal(ptr, fctx->elmalign);
-			fctx->elemdataptr = ptr;
-		}
+		elem = array_iter_next(&fctx->iter, &fcinfo->isnull, offset,
+							   fctx->elmlen, fctx->elmbyval, fctx->elmalign);
 
 		SRF_RETURN_NEXT(funcctx, elem);
 	}
@@ -5992,7 +6198,8 @@ array_replace_internal(ArrayType *array,
 	result->ndim = ndim;
 	result->dataoffset = dataoffset;
 	result->elemtype = element_type;
-	memcpy(ARR_DIMS(result), ARR_DIMS(array), 2 * ndim * sizeof(int));
+	memcpy(ARR_DIMS(result), ARR_DIMS(array), ndim * sizeof(int));
+	memcpy(ARR_LBOUND(result), ARR_LBOUND(array), ndim * sizeof(int));
 
 	if (remove)
 	{