Adding upstream version 15.4.upstream/15.4upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 912 insertions, 0 deletions

diff --git a/src/backend/utils/adt/array_userfuncs.c b/src/backend/utils/adt/array_userfuncs.c
new file mode 100644
index 0000000..e75c774
--- /dev/null
+++ b/src/backend/utils/adt/array_userfuncs.c
@@ -0,0 +1,912 @@
+/*-------------------------------------------------------------------------
+ *
+ * array_userfuncs.c
+ *	  Misc user-visible array support functions
+ *
+ * Copyright (c) 2003-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/adt/array_userfuncs.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "catalog/pg_type.h"
+#include "common/int.h"
+#include "utils/array.h"
+#include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/typcache.h"
+
+
+static Datum array_position_common(FunctionCallInfo fcinfo);
+
+
+/*
+ * fetch_array_arg_replace_nulls
+ *
+ * Fetch an array-valued argument in expanded form; if it's null, construct an
+ * empty array value of the proper data type.  Also cache basic element type
+ * information in fn_extra.
+ *
+ * Caution: if the input is a read/write pointer, this returns the input
+ * argument; so callers must be sure that their changes are "safe", that is
+ * they cannot leave the array in a corrupt state.
+ *
+ * If we're being called as an aggregate function, make sure any newly-made
+ * expanded array is allocated in the aggregate state context, so as to save
+ * copying operations.
+ */
+static ExpandedArrayHeader *
+fetch_array_arg_replace_nulls(FunctionCallInfo fcinfo, int argno)
+{
+	ExpandedArrayHeader *eah;
+	Oid			element_type;
+	ArrayMetaState *my_extra;
+	MemoryContext resultcxt;
+
+	/* If first time through, create datatype cache struct */
+	my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
+	if (my_extra == NULL)
+	{
+		my_extra = (ArrayMetaState *)
+			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
+							   sizeof(ArrayMetaState));
+		my_extra->element_type = InvalidOid;
+		fcinfo->flinfo->fn_extra = my_extra;
+	}
+
+	/* Figure out which context we want the result in */
+	if (!AggCheckCallContext(fcinfo, &resultcxt))
+		resultcxt = CurrentMemoryContext;
+
+	/* Now collect the array value */
+	if (!PG_ARGISNULL(argno))
+	{
+		MemoryContext oldcxt = MemoryContextSwitchTo(resultcxt);
+
+		eah = PG_GETARG_EXPANDED_ARRAYX(argno, my_extra);
+		MemoryContextSwitchTo(oldcxt);
+	}
+	else
+	{
+		/* We have to look up the array type and element type */
+		Oid			arr_typeid = get_fn_expr_argtype(fcinfo->flinfo, argno);
+
+		if (!OidIsValid(arr_typeid))
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 errmsg("could not determine input data type")));
+		element_type = get_element_type(arr_typeid);
+		if (!OidIsValid(element_type))
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("input data type is not an array")));
+
+		eah = construct_empty_expanded_array(element_type,
+											 resultcxt,
+											 my_extra);
+	}
+
+	return eah;
+}
+
+/*-----------------------------------------------------------------------------
+ * array_append :
+ *		push an element onto the end of a one-dimensional array
+ *----------------------------------------------------------------------------
+ */
+Datum
+array_append(PG_FUNCTION_ARGS)
+{
+	ExpandedArrayHeader *eah;
+	Datum		newelem;
+	bool		isNull;
+	Datum		result;
+	int		   *dimv,
+			   *lb;
+	int			indx;
+	ArrayMetaState *my_extra;
+
+	eah = fetch_array_arg_replace_nulls(fcinfo, 0);
+	isNull = PG_ARGISNULL(1);
+	if (isNull)
+		newelem = (Datum) 0;
+	else
+		newelem = PG_GETARG_DATUM(1);
+
+	if (eah->ndims == 1)
+	{
+		/* append newelem */
+		lb = eah->lbound;
+		dimv = eah->dims;
+
+		/* index of added elem is at lb[0] + (dimv[0] - 1) + 1 */
+		if (pg_add_s32_overflow(lb[0], dimv[0], &indx))
+			ereport(ERROR,
+					(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
+					 errmsg("integer out of range")));
+	}
+	else if (eah->ndims == 0)
+		indx = 1;
+	else
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_EXCEPTION),
+				 errmsg("argument must be empty or one-dimensional array")));
+
+	/* Perform element insertion */
+	my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
+
+	result = array_set_element(EOHPGetRWDatum(&eah->hdr),
+							   1, &indx, newelem, isNull,
+							   -1, my_extra->typlen, my_extra->typbyval, my_extra->typalign);
+
+	PG_RETURN_DATUM(result);
+}
+
+/*-----------------------------------------------------------------------------
+ * array_prepend :
+ *		push an element onto the front of a one-dimensional array
+ *----------------------------------------------------------------------------
+ */
+Datum
+array_prepend(PG_FUNCTION_ARGS)
+{
+	ExpandedArrayHeader *eah;
+	Datum		newelem;
+	bool		isNull;
+	Datum		result;
+	int		   *lb;
+	int			indx;
+	int			lb0;
+	ArrayMetaState *my_extra;
+
+	isNull = PG_ARGISNULL(0);
+	if (isNull)
+		newelem = (Datum) 0;
+	else
+		newelem = PG_GETARG_DATUM(0);
+	eah = fetch_array_arg_replace_nulls(fcinfo, 1);
+
+	if (eah->ndims == 1)
+	{
+		/* prepend newelem */
+		lb = eah->lbound;
+		lb0 = lb[0];
+
+		if (pg_sub_s32_overflow(lb0, 1, &indx))
+			ereport(ERROR,
+					(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
+					 errmsg("integer out of range")));
+	}
+	else if (eah->ndims == 0)
+	{
+		indx = 1;
+		lb0 = 1;
+	}
+	else
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_EXCEPTION),
+				 errmsg("argument must be empty or one-dimensional array")));
+
+	/* Perform element insertion */
+	my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
+
+	result = array_set_element(EOHPGetRWDatum(&eah->hdr),
+							   1, &indx, newelem, isNull,
+							   -1, my_extra->typlen, my_extra->typbyval, my_extra->typalign);
+
+	/* Readjust result's LB to match the input's, as expected for prepend */
+	Assert(result == EOHPGetRWDatum(&eah->hdr));
+	if (eah->ndims == 1)
+	{
+		/* This is ok whether we've deconstructed or not */
+		eah->lbound[0] = lb0;
+	}
+
+	PG_RETURN_DATUM(result);
+}
+
+/*-----------------------------------------------------------------------------
+ * array_cat :
+ *		concatenate two nD arrays to form an nD array, or
+ *		push an (n-1)D array onto the end of an nD array
+ *----------------------------------------------------------------------------
+ */
+Datum
+array_cat(PG_FUNCTION_ARGS)
+{
+	ArrayType  *v1,
+			   *v2;
+	ArrayType  *result;
+	int		   *dims,
+			   *lbs,
+				ndims,
+				nitems,
+				ndatabytes,
+				nbytes;
+	int		   *dims1,
+			   *lbs1,
+				ndims1,
+				nitems1,
+				ndatabytes1;
+	int		   *dims2,
+			   *lbs2,
+				ndims2,
+				nitems2,
+				ndatabytes2;
+	int			i;
+	char	   *dat1,
+			   *dat2;
+	bits8	   *bitmap1,
+			   *bitmap2;
+	Oid			element_type;
+	Oid			element_type1;
+	Oid			element_type2;
+	int32		dataoffset;
+
+	/* Concatenating a null array is a no-op, just return the other input */
+	if (PG_ARGISNULL(0))
+	{
+		if (PG_ARGISNULL(1))
+			PG_RETURN_NULL();
+		result = PG_GETARG_ARRAYTYPE_P(1);
+		PG_RETURN_ARRAYTYPE_P(result);
+	}
+	if (PG_ARGISNULL(1))
+	{
+		result = PG_GETARG_ARRAYTYPE_P(0);
+		PG_RETURN_ARRAYTYPE_P(result);
+	}
+
+	v1 = PG_GETARG_ARRAYTYPE_P(0);
+	v2 = PG_GETARG_ARRAYTYPE_P(1);
+
+	element_type1 = ARR_ELEMTYPE(v1);
+	element_type2 = ARR_ELEMTYPE(v2);
+
+	/* Check we have matching element types */
+	if (element_type1 != element_type2)
+		ereport(ERROR,
+				(errcode(ERRCODE_DATATYPE_MISMATCH),
+				 errmsg("cannot concatenate incompatible arrays"),
+				 errdetail("Arrays with element types %s and %s are not "
+						   "compatible for concatenation.",
+						   format_type_be(element_type1),
+						   format_type_be(element_type2))));
+
+	/* OK, use it */
+	element_type = element_type1;
+
+	/*----------
+	 * We must have one of the following combinations of inputs:
+	 * 1) one empty array, and one non-empty array
+	 * 2) both arrays empty
+	 * 3) two arrays with ndims1 == ndims2
+	 * 4) ndims1 == ndims2 - 1
+	 * 5) ndims1 == ndims2 + 1
+	 *----------
+	 */
+	ndims1 = ARR_NDIM(v1);
+	ndims2 = ARR_NDIM(v2);
+
+	/*
+	 * short circuit - if one input array is empty, and the other is not, we
+	 * return the non-empty one as the result
+	 *
+	 * if both are empty, return the first one
+	 */
+	if (ndims1 == 0 && ndims2 > 0)
+		PG_RETURN_ARRAYTYPE_P(v2);
+
+	if (ndims2 == 0)
+		PG_RETURN_ARRAYTYPE_P(v1);
+
+	/* the rest fall under rule 3, 4, or 5 */
+	if (ndims1 != ndims2 &&
+		ndims1 != ndims2 - 1 &&
+		ndims1 != ndims2 + 1)
+		ereport(ERROR,
+				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
+				 errmsg("cannot concatenate incompatible arrays"),
+				 errdetail("Arrays of %d and %d dimensions are not "
+						   "compatible for concatenation.",
+						   ndims1, ndims2)));
+
+	/* get argument array details */
+	lbs1 = ARR_LBOUND(v1);
+	lbs2 = ARR_LBOUND(v2);
+	dims1 = ARR_DIMS(v1);
+	dims2 = ARR_DIMS(v2);
+	dat1 = ARR_DATA_PTR(v1);
+	dat2 = ARR_DATA_PTR(v2);
+	bitmap1 = ARR_NULLBITMAP(v1);
+	bitmap2 = ARR_NULLBITMAP(v2);
+	nitems1 = ArrayGetNItems(ndims1, dims1);
+	nitems2 = ArrayGetNItems(ndims2, dims2);
+	ndatabytes1 = ARR_SIZE(v1) - ARR_DATA_OFFSET(v1);
+	ndatabytes2 = ARR_SIZE(v2) - ARR_DATA_OFFSET(v2);
+
+	if (ndims1 == ndims2)
+	{
+		/*
+		 * resulting array is made up of the elements (possibly arrays
+		 * themselves) of the input argument arrays
+		 */
+		ndims = ndims1;
+		dims = (int *) palloc(ndims * sizeof(int));
+		lbs = (int *) palloc(ndims * sizeof(int));
+
+		dims[0] = dims1[0] + dims2[0];
+		lbs[0] = lbs1[0];
+
+		for (i = 1; i < ndims; i++)
+		{
+			if (dims1[i] != dims2[i] || lbs1[i] != lbs2[i])
+				ereport(ERROR,
+						(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
+						 errmsg("cannot concatenate incompatible arrays"),
+						 errdetail("Arrays with differing element dimensions are "
+								   "not compatible for concatenation.")));
+
+			dims[i] = dims1[i];
+			lbs[i] = lbs1[i];
+		}
+	}
+	else if (ndims1 == ndims2 - 1)
+	{
+		/*
+		 * resulting array has the second argument as the outer array, with
+		 * the first argument inserted at the front of the outer dimension
+		 */
+		ndims = ndims2;
+		dims = (int *) palloc(ndims * sizeof(int));
+		lbs = (int *) palloc(ndims * sizeof(int));
+		memcpy(dims, dims2, ndims * sizeof(int));
+		memcpy(lbs, lbs2, ndims * sizeof(int));
+
+		/* increment number of elements in outer array */
+		dims[0] += 1;
+
+		/* make sure the added element matches our existing elements */
+		for (i = 0; i < ndims1; i++)
+		{
+			if (dims1[i] != dims[i + 1] || lbs1[i] != lbs[i + 1])
+				ereport(ERROR,
+						(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
+						 errmsg("cannot concatenate incompatible arrays"),
+						 errdetail("Arrays with differing dimensions are not "
+								   "compatible for concatenation.")));
+		}
+	}
+	else
+	{
+		/*
+		 * (ndims1 == ndims2 + 1)
+		 *
+		 * resulting array has the first argument as the outer array, with the
+		 * second argument appended to the end of the outer dimension
+		 */
+		ndims = ndims1;
+		dims = (int *) palloc(ndims * sizeof(int));
+		lbs = (int *) palloc(ndims * sizeof(int));
+		memcpy(dims, dims1, ndims * sizeof(int));
+		memcpy(lbs, lbs1, ndims * sizeof(int));
+
+		/* increment number of elements in outer array */
+		dims[0] += 1;
+
+		/* make sure the added element matches our existing elements */
+		for (i = 0; i < ndims2; i++)
+		{
+			if (dims2[i] != dims[i + 1] || lbs2[i] != lbs[i + 1])
+				ereport(ERROR,
+						(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
+						 errmsg("cannot concatenate incompatible arrays"),
+						 errdetail("Arrays with differing dimensions are not "
+								   "compatible for concatenation.")));
+		}
+	}
+
+	/* Do this mainly for overflow checking */
+	nitems = ArrayGetNItems(ndims, dims);
+	ArrayCheckBounds(ndims, dims, lbs);
+
+	/* build the result array */
+	ndatabytes = ndatabytes1 + ndatabytes2;
+	if (ARR_HASNULL(v1) || ARR_HASNULL(v2))
+	{
+		dataoffset = ARR_OVERHEAD_WITHNULLS(ndims, nitems);
+		nbytes = ndatabytes + dataoffset;
+	}
+	else
+	{
+		dataoffset = 0;			/* marker for no null bitmap */
+		nbytes = ndatabytes + ARR_OVERHEAD_NONULLS(ndims);
+	}
+	result = (ArrayType *) palloc0(nbytes);
+	SET_VARSIZE(result, nbytes);
+	result->ndim = ndims;
+	result->dataoffset = dataoffset;
+	result->elemtype = element_type;
+	memcpy(ARR_DIMS(result), dims, ndims * sizeof(int));
+	memcpy(ARR_LBOUND(result), lbs, ndims * sizeof(int));
+	/* data area is arg1 then arg2 */
+	memcpy(ARR_DATA_PTR(result), dat1, ndatabytes1);
+	memcpy(ARR_DATA_PTR(result) + ndatabytes1, dat2, ndatabytes2);
+	/* handle the null bitmap if needed */
+	if (ARR_HASNULL(result))
+	{
+		array_bitmap_copy(ARR_NULLBITMAP(result), 0,
+						  bitmap1, 0,
+						  nitems1);
+		array_bitmap_copy(ARR_NULLBITMAP(result), nitems1,
+						  bitmap2, 0,
+						  nitems2);
+	}
+
+	PG_RETURN_ARRAYTYPE_P(result);
+}
+
+
+/*
+ * ARRAY_AGG(anynonarray) aggregate function
+ */
+Datum
+array_agg_transfn(PG_FUNCTION_ARGS)
+{
+	Oid			arg1_typeid = get_fn_expr_argtype(fcinfo->flinfo, 1);
+	MemoryContext aggcontext;
+	ArrayBuildState *state;
+	Datum		elem;
+
+	if (arg1_typeid == InvalidOid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("could not determine input data type")));
+
+	/*
+	 * Note: we do not need a run-time check about whether arg1_typeid is a
+	 * valid array element type, because the parser would have verified that
+	 * while resolving the input/result types of this polymorphic aggregate.
+	 */
+
+	if (!AggCheckCallContext(fcinfo, &aggcontext))
+	{
+		/* cannot be called directly because of internal-type argument */
+		elog(ERROR, "array_agg_transfn called in non-aggregate context");
+	}
+
+	if (PG_ARGISNULL(0))
+		state = initArrayResult(arg1_typeid, aggcontext, false);
+	else
+		state = (ArrayBuildState *) PG_GETARG_POINTER(0);
+
+	elem = PG_ARGISNULL(1) ? (Datum) 0 : PG_GETARG_DATUM(1);
+
+	state = accumArrayResult(state,
+							 elem,
+							 PG_ARGISNULL(1),
+							 arg1_typeid,
+							 aggcontext);
+
+	/*
+	 * The transition type for array_agg() is declared to be "internal", which
+	 * is a pass-by-value type the same size as a pointer.  So we can safely
+	 * pass the ArrayBuildState pointer through nodeAgg.c's machinations.
+	 */
+	PG_RETURN_POINTER(state);
+}
+
+Datum
+array_agg_finalfn(PG_FUNCTION_ARGS)
+{
+	Datum		result;
+	ArrayBuildState *state;
+	int			dims[1];
+	int			lbs[1];
+
+	/* cannot be called directly because of internal-type argument */
+	Assert(AggCheckCallContext(fcinfo, NULL));
+
+	state = PG_ARGISNULL(0) ? NULL : (ArrayBuildState *) PG_GETARG_POINTER(0);
+
+	if (state == NULL)
+		PG_RETURN_NULL();		/* returns null iff no input values */
+
+	dims[0] = state->nelems;
+	lbs[0] = 1;
+
+	/*
+	 * Make the result.  We cannot release the ArrayBuildState because
+	 * sometimes aggregate final functions are re-executed.  Rather, it is
+	 * nodeAgg.c's responsibility to reset the aggcontext when it's safe to do
+	 * so.
+	 */
+	result = makeMdArrayResult(state, 1, dims, lbs,
+							   CurrentMemoryContext,
+							   false);
+
+	PG_RETURN_DATUM(result);
+}
+
+/*
+ * ARRAY_AGG(anyarray) aggregate function
+ */
+Datum
+array_agg_array_transfn(PG_FUNCTION_ARGS)
+{
+	Oid			arg1_typeid = get_fn_expr_argtype(fcinfo->flinfo, 1);
+	MemoryContext aggcontext;
+	ArrayBuildStateArr *state;
+
+	if (arg1_typeid == InvalidOid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("could not determine input data type")));
+
+	/*
+	 * Note: we do not need a run-time check about whether arg1_typeid is a
+	 * valid array type, because the parser would have verified that while
+	 * resolving the input/result types of this polymorphic aggregate.
+	 */
+
+	if (!AggCheckCallContext(fcinfo, &aggcontext))
+	{
+		/* cannot be called directly because of internal-type argument */
+		elog(ERROR, "array_agg_array_transfn called in non-aggregate context");
+	}
+
+
+	if (PG_ARGISNULL(0))
+		state = initArrayResultArr(arg1_typeid, InvalidOid, aggcontext, false);
+	else
+		state = (ArrayBuildStateArr *) PG_GETARG_POINTER(0);
+
+	state = accumArrayResultArr(state,
+								PG_GETARG_DATUM(1),
+								PG_ARGISNULL(1),
+								arg1_typeid,
+								aggcontext);
+
+	/*
+	 * The transition type for array_agg() is declared to be "internal", which
+	 * is a pass-by-value type the same size as a pointer.  So we can safely
+	 * pass the ArrayBuildStateArr pointer through nodeAgg.c's machinations.
+	 */
+	PG_RETURN_POINTER(state);
+}
+
+Datum
+array_agg_array_finalfn(PG_FUNCTION_ARGS)
+{
+	Datum		result;
+	ArrayBuildStateArr *state;
+
+	/* cannot be called directly because of internal-type argument */
+	Assert(AggCheckCallContext(fcinfo, NULL));
+
+	state = PG_ARGISNULL(0) ? NULL : (ArrayBuildStateArr *) PG_GETARG_POINTER(0);
+
+	if (state == NULL)
+		PG_RETURN_NULL();		/* returns null iff no input values */
+
+	/*
+	 * Make the result.  We cannot release the ArrayBuildStateArr because
+	 * sometimes aggregate final functions are re-executed.  Rather, it is
+	 * nodeAgg.c's responsibility to reset the aggcontext when it's safe to do
+	 * so.
+	 */
+	result = makeArrayResultArr(state, CurrentMemoryContext, false);
+
+	PG_RETURN_DATUM(result);
+}
+
+/*-----------------------------------------------------------------------------
+ * array_position, array_position_start :
+ *			return the offset of a value in an array.
+ *
+ * IS NOT DISTINCT FROM semantics are used for comparisons.  Return NULL when
+ * the value is not found.
+ *-----------------------------------------------------------------------------
+ */
+Datum
+array_position(PG_FUNCTION_ARGS)
+{
+	return array_position_common(fcinfo);
+}
+
+Datum
+array_position_start(PG_FUNCTION_ARGS)
+{
+	return array_position_common(fcinfo);
+}
+
+/*
+ * array_position_common
+ *		Common code for array_position and array_position_start
+ *
+ * These are separate wrappers for the sake of opr_sanity regression test.
+ * They are not strict so we have to test for null inputs explicitly.
+ */
+static Datum
+array_position_common(FunctionCallInfo fcinfo)
+{
+	ArrayType  *array;
+	Oid			collation = PG_GET_COLLATION();
+	Oid			element_type;
+	Datum		searched_element,
+				value;
+	bool		isnull;
+	int			position,
+				position_min;
+	bool		found = false;
+	TypeCacheEntry *typentry;
+	ArrayMetaState *my_extra;
+	bool		null_search;
+	ArrayIterator array_iterator;
+
+	if (PG_ARGISNULL(0))
+		PG_RETURN_NULL();
+
+	array = PG_GETARG_ARRAYTYPE_P(0);
+
+	/*
+	 * We refuse to search for elements in multi-dimensional arrays, since we
+	 * have no good way to report the element's location in the array.
+	 */
+	if (ARR_NDIM(array) > 1)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("searching for elements in multidimensional arrays is not supported")));
+
+	/* Searching in an empty array is well-defined, though: it always fails */
+	if (ARR_NDIM(array) < 1)
+		PG_RETURN_NULL();
+
+	if (PG_ARGISNULL(1))
+	{
+		/* fast return when the array doesn't have nulls */
+		if (!array_contains_nulls(array))
+			PG_RETURN_NULL();
+		searched_element = (Datum) 0;
+		null_search = true;
+	}
+	else
+	{
+		searched_element = PG_GETARG_DATUM(1);
+		null_search = false;
+	}
+
+	element_type = ARR_ELEMTYPE(array);
+	position = (ARR_LBOUND(array))[0] - 1;
+
+	/* figure out where to start */
+	if (PG_NARGS() == 3)
+	{
+		if (PG_ARGISNULL(2))
+			ereport(ERROR,
+					(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+					 errmsg("initial position must not be null")));
+
+		position_min = PG_GETARG_INT32(2);
+	}
+	else
+		position_min = (ARR_LBOUND(array))[0];
+
+	/*
+	 * We arrange to look up type info for array_create_iterator only once per
+	 * series of calls, assuming the element type doesn't change underneath
+	 * us.
+	 */
+	my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
+	if (my_extra == NULL)
+	{
+		fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
+													  sizeof(ArrayMetaState));
+		my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
+		my_extra->element_type = ~element_type;
+	}
+
+	if (my_extra->element_type != element_type)
+	{
+		get_typlenbyvalalign(element_type,
+							 &my_extra->typlen,
+							 &my_extra->typbyval,
+							 &my_extra->typalign);
+
+		typentry = lookup_type_cache(element_type, TYPECACHE_EQ_OPR_FINFO);
+
+		if (!OidIsValid(typentry->eq_opr_finfo.fn_oid))
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_FUNCTION),
+					 errmsg("could not identify an equality operator for type %s",
+							format_type_be(element_type))));
+
+		my_extra->element_type = element_type;
+		fmgr_info_cxt(typentry->eq_opr_finfo.fn_oid, &my_extra->proc,
+					  fcinfo->flinfo->fn_mcxt);
+	}
+
+	/* Examine each array element until we find a match. */
+	array_iterator = array_create_iterator(array, 0, my_extra);
+	while (array_iterate(array_iterator, &value, &isnull))
+	{
+		position++;
+
+		/* skip initial elements if caller requested so */
+		if (position < position_min)
+			continue;
+
+		/*
+		 * Can't look at the array element's value if it's null; but if we
+		 * search for null, we have a hit and are done.
+		 */
+		if (isnull || null_search)
+		{
+			if (isnull && null_search)
+			{
+				found = true;
+				break;
+			}
+			else
+				continue;
+		}
+
+		/* not nulls, so run the operator */
+		if (DatumGetBool(FunctionCall2Coll(&my_extra->proc, collation,
+										   searched_element, value)))
+		{
+			found = true;
+			break;
+		}
+	}
+
+	array_free_iterator(array_iterator);
+
+	/* Avoid leaking memory when handed toasted input */
+	PG_FREE_IF_COPY(array, 0);
+
+	if (!found)
+		PG_RETURN_NULL();
+
+	PG_RETURN_INT32(position);
+}
+
+/*-----------------------------------------------------------------------------
+ * array_positions :
+ *			return an array of positions of a value in an array.
+ *
+ * IS NOT DISTINCT FROM semantics are used for comparisons.  Returns NULL when
+ * the input array is NULL.  When the value is not found in the array, returns
+ * an empty array.
+ *
+ * This is not strict so we have to test for null inputs explicitly.
+ *-----------------------------------------------------------------------------
+ */
+Datum
+array_positions(PG_FUNCTION_ARGS)
+{
+	ArrayType  *array;
+	Oid			collation = PG_GET_COLLATION();
+	Oid			element_type;
+	Datum		searched_element,
+				value;
+	bool		isnull;
+	int			position;
+	TypeCacheEntry *typentry;
+	ArrayMetaState *my_extra;
+	bool		null_search;
+	ArrayIterator array_iterator;
+	ArrayBuildState *astate = NULL;
+
+	if (PG_ARGISNULL(0))
+		PG_RETURN_NULL();
+
+	array = PG_GETARG_ARRAYTYPE_P(0);
+
+	/*
+	 * We refuse to search for elements in multi-dimensional arrays, since we
+	 * have no good way to report the element's location in the array.
+	 */
+	if (ARR_NDIM(array) > 1)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("searching for elements in multidimensional arrays is not supported")));
+
+	astate = initArrayResult(INT4OID, CurrentMemoryContext, false);
+
+	/* Searching in an empty array is well-defined, though: it always fails */
+	if (ARR_NDIM(array) < 1)
+		PG_RETURN_DATUM(makeArrayResult(astate, CurrentMemoryContext));
+
+	if (PG_ARGISNULL(1))
+	{
+		/* fast return when the array doesn't have nulls */
+		if (!array_contains_nulls(array))
+			PG_RETURN_DATUM(makeArrayResult(astate, CurrentMemoryContext));
+		searched_element = (Datum) 0;
+		null_search = true;
+	}
+	else
+	{
+		searched_element = PG_GETARG_DATUM(1);
+		null_search = false;
+	}
+
+	element_type = ARR_ELEMTYPE(array);
+	position = (ARR_LBOUND(array))[0] - 1;
+
+	/*
+	 * We arrange to look up type info for array_create_iterator only once per
+	 * series of calls, assuming the element type doesn't change underneath
+	 * us.
+	 */
+	my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
+	if (my_extra == NULL)
+	{
+		fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
+													  sizeof(ArrayMetaState));
+		my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
+		my_extra->element_type = ~element_type;
+	}
+
+	if (my_extra->element_type != element_type)
+	{
+		get_typlenbyvalalign(element_type,
+							 &my_extra->typlen,
+							 &my_extra->typbyval,
+							 &my_extra->typalign);
+
+		typentry = lookup_type_cache(element_type, TYPECACHE_EQ_OPR_FINFO);
+
+		if (!OidIsValid(typentry->eq_opr_finfo.fn_oid))
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_FUNCTION),
+					 errmsg("could not identify an equality operator for type %s",
+							format_type_be(element_type))));
+
+		my_extra->element_type = element_type;
+		fmgr_info_cxt(typentry->eq_opr_finfo.fn_oid, &my_extra->proc,
+					  fcinfo->flinfo->fn_mcxt);
+	}
+
+	/*
+	 * Accumulate each array position iff the element matches the given
+	 * element.
+	 */
+	array_iterator = array_create_iterator(array, 0, my_extra);
+	while (array_iterate(array_iterator, &value, &isnull))
+	{
+		position += 1;
+
+		/*
+		 * Can't look at the array element's value if it's null; but if we
+		 * search for null, we have a hit.
+		 */
+		if (isnull || null_search)
+		{
+			if (isnull && null_search)
+				astate =
+					accumArrayResult(astate, Int32GetDatum(position), false,
+									 INT4OID, CurrentMemoryContext);
+
+			continue;
+		}
+
+		/* not nulls, so run the operator */
+		if (DatumGetBool(FunctionCall2Coll(&my_extra->proc, collation,
+										   searched_element, value)))
+			astate =
+				accumArrayResult(astate, Int32GetDatum(position), false,
+								 INT4OID, CurrentMemoryContext);
+	}
+
+	array_free_iterator(array_iterator);
+
+	/* Avoid leaking memory when handed toasted input */
+	PG_FREE_IF_COPY(array, 0);
+
+	PG_RETURN_DATUM(makeArrayResult(astate, CurrentMemoryContext));
+}