generateClonedIndexStmt(CreateStmtContext *cxt, Relation source_idx,
						const AttrNumber *attmap, int attmap_length)
{
	Oid			source_relid = RelationGetRelid(source_idx);
	Form_pg_attribute *attrs = RelationGetDescr(source_idx)->attrs;
	HeapTuple	ht_idxrel;
	HeapTuple	ht_idx;
	Form_pg_class idxrelrec;
	Form_pg_index idxrec;
	Form_pg_am	amrec;
	oidvector  *indcollation;
	oidvector  *indclass;
	IndexStmt  *index;
	List	   *indexprs;
	ListCell   *indexpr_item;
	Oid			indrelid;
	int			keyno;
	Oid			keycoltype;
	Datum		datum;
	bool		isnull;

	/*
	 * Fetch pg_class tuple of source index.  We can't use the copy in the
	 * relcache entry because it doesn't include optional fields.
	 */
	ht_idxrel = SearchSysCache1(RELOID, ObjectIdGetDatum(source_relid));
	if (!HeapTupleIsValid(ht_idxrel))
		elog(ERROR, "cache lookup failed for relation %u", source_relid);
	idxrelrec = (Form_pg_class) GETSTRUCT(ht_idxrel);

	/* Fetch pg_index tuple for source index from relcache entry */
	ht_idx = source_idx->rd_indextuple;
	idxrec = (Form_pg_index) GETSTRUCT(ht_idx);
	indrelid = idxrec->indrelid;

	/* Fetch pg_am tuple for source index from relcache entry */
	amrec = source_idx->rd_am;

	/* Extract indcollation from the pg_index tuple */
	datum = SysCacheGetAttr(INDEXRELID, ht_idx,
							Anum_pg_index_indcollation, &isnull);
	Assert(!isnull);
	indcollation = (oidvector *) DatumGetPointer(datum);

	/* Extract indclass from the pg_index tuple */
	datum = SysCacheGetAttr(INDEXRELID, ht_idx,
							Anum_pg_index_indclass, &isnull);
	Assert(!isnull);
	indclass = (oidvector *) DatumGetPointer(datum);

	/* Begin building the IndexStmt */
	index = makeNode(IndexStmt);
	index->relation = cxt->relation;
	index->accessMethod = pstrdup(NameStr(amrec->amname));
	if (OidIsValid(idxrelrec->reltablespace))
		index->tableSpace = get_tablespace_name(idxrelrec->reltablespace);
	else
		index->tableSpace = NULL;
	index->excludeOpNames = NIL;
	index->idxcomment = NULL;
	index->indexOid = InvalidOid;
	index->oldNode = InvalidOid;
	index->unique = idxrec->indisunique;
	index->primary = idxrec->indisprimary;
	index->concurrent = false;

	/*
	 * We don't try to preserve the name of the source index; instead, just
	 * let DefineIndex() choose a reasonable name.
	 */
	index->idxname = NULL;

	/*
	 * If the index is marked PRIMARY or has an exclusion condition, it's
	 * certainly from a constraint; else, if it's not marked UNIQUE, it
	 * certainly isn't.  If it is or might be from a constraint, we have to
	 * fetch the pg_constraint record.
	 */
	if (index->primary || index->unique || idxrec->indisexclusion)
	{
		Oid			constraintId = get_index_constraint(source_relid);

		if (OidIsValid(constraintId))
		{
			HeapTuple	ht_constr;
			Form_pg_constraint conrec;

			ht_constr = SearchSysCache1(CONSTROID,
										ObjectIdGetDatum(constraintId));
			if (!HeapTupleIsValid(ht_constr))
				elog(ERROR, "cache lookup failed for constraint %u",
					 constraintId);
			conrec = (Form_pg_constraint) GETSTRUCT(ht_constr);

			index->isconstraint = true;
			index->deferrable = conrec->condeferrable;
			index->initdeferred = conrec->condeferred;

			/* If it's an exclusion constraint, we need the operator names */
			if (idxrec->indisexclusion)
			{
				Datum	   *elems;
				int			nElems;
				int			i;

				Assert(conrec->contype == CONSTRAINT_EXCLUSION);
				/* Extract operator OIDs from the pg_constraint tuple */
				datum = SysCacheGetAttr(CONSTROID, ht_constr,
										Anum_pg_constraint_conexclop,
										&isnull);
				if (isnull)
					elog(ERROR, "null conexclop for constraint %u",
						 constraintId);

				deconstruct_array(DatumGetArrayTypeP(datum),
								  OIDOID, sizeof(Oid), true, 'i',
								  &elems, NULL, &nElems);

				for (i = 0; i < nElems; i++)
				{
					Oid			operid = DatumGetObjectId(elems[i]);
					HeapTuple	opertup;
					Form_pg_operator operform;
					char	   *oprname;
					char	   *nspname;
					List	   *namelist;

					opertup = SearchSysCache1(OPEROID,
											  ObjectIdGetDatum(operid));
					if (!HeapTupleIsValid(opertup))
						elog(ERROR, "cache lookup failed for operator %u",
							 operid);
					operform = (Form_pg_operator) GETSTRUCT(opertup);
					oprname = pstrdup(NameStr(operform->oprname));
					/* For simplicity we always schema-qualify the op name */
					nspname = get_namespace_name(operform->oprnamespace);
					namelist = list_make2(makeString(nspname),
										  makeString(oprname));
					index->excludeOpNames = lappend(index->excludeOpNames,
													namelist);
					ReleaseSysCache(opertup);
				}
			}

			ReleaseSysCache(ht_constr);
		}
		else
			index->isconstraint = false;
	}
	else
		index->isconstraint = false;

	/* Get the index expressions, if any */
	datum = SysCacheGetAttr(INDEXRELID, ht_idx,
							Anum_pg_index_indexprs, &isnull);
	if (!isnull)
	{
		char	   *exprsString;

		exprsString = TextDatumGetCString(datum);
		indexprs = (List *) stringToNode(exprsString);
	}
	else
		indexprs = NIL;

	/* Build the list of IndexElem */
	index->indexParams = NIL;

	indexpr_item = list_head(indexprs);
	for (keyno = 0; keyno < idxrec->indnatts; keyno++)
	{
		IndexElem  *iparam;
		AttrNumber	attnum = idxrec->indkey.values[keyno];
		int16		opt = source_idx->rd_indoption[keyno];

		iparam = makeNode(IndexElem);

		if (AttributeNumberIsValid(attnum))
		{
			/* Simple index column */
			char	   *attname;

			attname = get_relid_attribute_name(indrelid, attnum);
			keycoltype = get_atttype(indrelid, attnum);

			iparam->name = attname;
			iparam->expr = NULL;
		}
		else
		{
			/* Expressional index */
			Node	   *indexkey;
			bool		found_whole_row;

			if (indexpr_item == NULL)
				elog(ERROR, "too few entries in indexprs list");
			indexkey = (Node *) lfirst(indexpr_item);
			indexpr_item = lnext(indexpr_item);

			/* Adjust Vars to match new table's column numbering */
			indexkey = map_variable_attnos(indexkey,
										   1, 0,
										   attmap, attmap_length,
										   &found_whole_row);

			/* As in transformTableLikeClause, reject whole-row variables */
			if (found_whole_row)
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("cannot convert whole-row table reference"),
						 errdetail("Index \"%s\" contains a whole-row table reference.",
								   RelationGetRelationName(source_idx))));

			iparam->name = NULL;
			iparam->expr = indexkey;

			keycoltype = exprType(indexkey);
		}

		/* Copy the original index column name */
		iparam->indexcolname = pstrdup(NameStr(attrs[keyno]->attname));

		/* Add the collation name, if non-default */
		iparam->collation = get_collation(indcollation->values[keyno], keycoltype);

		/* Add the operator class name, if non-default */
		iparam->opclass = get_opclass(indclass->values[keyno], keycoltype);

		iparam->ordering = SORTBY_DEFAULT;
		iparam->nulls_ordering = SORTBY_NULLS_DEFAULT;

		/* Adjust options if necessary */
		if (amrec->amcanorder)
		{
			/*
			 * If it supports sort ordering, copy DESC and NULLS opts. Don't
			 * set non-default settings unnecessarily, though, so as to
			 * improve the chance of recognizing equivalence to constraint
			 * indexes.
			 */
			if (opt & INDOPTION_DESC)
			{
				iparam->ordering = SORTBY_DESC;
				if ((opt & INDOPTION_NULLS_FIRST) == 0)
					iparam->nulls_ordering = SORTBY_NULLS_LAST;
			}
			else
			{
				if (opt & INDOPTION_NULLS_FIRST)
					iparam->nulls_ordering = SORTBY_NULLS_FIRST;
			}
		}

		index->indexParams = lappend(index->indexParams, iparam);
	}

	/* Copy reloptions if any */
	datum = SysCacheGetAttr(RELOID, ht_idxrel,
							Anum_pg_class_reloptions, &isnull);
	if (!isnull)
		index->options = untransformRelOptions(datum);

	/* If it's a partial index, decompile and append the predicate */
	datum = SysCacheGetAttr(INDEXRELID, ht_idx,
							Anum_pg_index_indpred, &isnull);
	if (!isnull)
	{
		char	   *pred_str;
		Node	   *pred_tree;
		bool		found_whole_row;

		/* Convert text string to node tree */
		pred_str = TextDatumGetCString(datum);
		pred_tree = (Node *) stringToNode(pred_str);

		/* Adjust Vars to match new table's column numbering */
		pred_tree = map_variable_attnos(pred_tree,
										1, 0,
										attmap, attmap_length,
										&found_whole_row);

		/* As in transformTableLikeClause, reject whole-row variables */
		if (found_whole_row)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("cannot convert whole-row table reference"),
			  errdetail("Index \"%s\" contains a whole-row table reference.",
						RelationGetRelationName(source_idx))));

		index->whereClause = pred_tree;
	}

	/* Clean up */
	ReleaseSysCache(ht_idxrel);

	return index;
}