Remove unnecessary use of rec_get_nth_cfield() and unnecessary copying

rec_get_nth_cfield(): Remove the heap parameter.
Copying the default value of a field into a heap is only
needed in row_build_low(type=ROW_COPY_DATA).

rec_get_nth_field(): Use the original definition.
There are very few rec_get_nth_cfield() calls compared to
rec_get_nth_field().

storage/innobase/handler/handler0alter.cc

@@ -1958,8 +1958,7 @@ innobase_rec_to_mysql(
 			continue;
 		}
 
-		/* ifield is read only, the heap can be NULL */
-		ifield = rec_get_nth_cfield(rec, offsets, ipos, index, NULL, &ilen);
+		ifield = rec_get_nth_cfield(rec, index, offsets, ipos, &ilen);
 
 		/* Assign the NULL flag */
 		if (ilen == UNIV_SQL_NULL) {

storage/innobase/include/rem0rec.h

@@ -586,26 +586,23 @@ rec_get_nth_field_offs(
 	ulint*		len)	/*!< out: length of the field; UNIV_SQL_NULL
 				if SQL null */
 	MY_ATTRIBUTE((nonnull));
+#define rec_get_nth_field(rec, offsets, n, len) \
+((rec) + rec_get_nth_field_offs(offsets, n, len))
 
-/************************************************************//**
-Get the nth field from cluster index
-@return pointer of field(Maybe get the pointer of default value of dictionary) */
+/** Get the nth field from an index.
+@param[in]	rec	index record
+@param[in]	index	index
+@param[in]	offsets	rec_get_offsets(rec, index)
+@param[in]	n	field number
+@param[out]	len	length of the field in bytes, or UNIV_SQL_NULL
+@return a read-only copy of the index field */
 const byte*
 rec_get_nth_cfield(
-	const rec_t*		rec,	/*!< in: rec */
-	const ulint*		offsets,/*!< in: array returned by rec_get_offsets() */
-	ulint				n,		/*!< in: index of the field */
-	const dict_index_t*	index,	/*!< in: dict_index of rec */
-	mem_heap_t*			heap,   /*!< in: mem_heap for default 
-									value of instant added columns */
-	ulint*				len); 	/*!< out: length of the field; UNIV_SQL_NULL 
-									if SQL null */
-
-/* 	Never return DEFAULT value(UNIV_SQL_DEFAULT) 
-	It always return pointer inside the record
-*/
-#define rec_get_nth_field(rec, offsets, n, len) \
-(byte*)rec_get_nth_cfield(rec, offsets, n, NULL, NULL, len)
+	const rec_t*		rec,
+	const dict_index_t*	index,
+	const ulint*		offsets,
+	ulint			n,
+	ulint*			len);
 
 /******************************************************//**
 Determine if the offsets are for a record containing null BLOB pointers.

storage/innobase/page/page0cur.cc

@@ -272,7 +272,7 @@ page_cur_rec_field_extends(
 
 	type = dfield_get_type(dfield);
 
-	rec_f = rec_get_nth_cfield(rec, offsets, n, index, NULL, &rec_f_len);
+	rec_f = rec_get_nth_field(rec, offsets, n, &rec_f_len);
 
 	if (type->mtype == DATA_VARCHAR
 	    || type->mtype == DATA_CHAR

storage/innobase/rem/rem0cmp.cc

@@ -1018,8 +1018,8 @@ cmp_rec_rec_simple_field(
 	ut_ad(!rec_offs_nth_extern(offsets1, n));
 	ut_ad(!rec_offs_nth_extern(offsets2, n));
 
-	rec1_b_ptr = rec_get_nth_cfield(rec1, offsets1, n, index, NULL, &rec1_f_len);
-	rec2_b_ptr = rec_get_nth_cfield(rec2, offsets2, n, index, NULL, &rec2_f_len);
+	rec1_b_ptr = rec_get_nth_field(rec1, offsets1, n, &rec1_f_len);
+	rec2_b_ptr = rec_get_nth_field(rec2, offsets2, n, &rec2_f_len);
 
 	return(cmp_data(col->mtype, col->prtype,
 			rec1_b_ptr, rec1_f_len, rec2_b_ptr, rec2_f_len));
@@ -1205,11 +1205,13 @@ cmp_rec_rec_with_match(
 		DB_ROLL_PTR, and any externally stored columns. */
 		ut_ad(!rec_offs_nth_extern(offsets1, cur_field));
 		ut_ad(!rec_offs_nth_extern(offsets2, cur_field));
+		ut_ad(!rec_offs_nth_default(offsets1, cur_field));
+		ut_ad(!rec_offs_nth_default(offsets2, cur_field));
 
-		rec1_b_ptr = rec_get_nth_cfield(rec1, offsets1,
-					       cur_field, index, NULL, &rec1_f_len);
-		rec2_b_ptr = rec_get_nth_cfield(rec2, offsets2,
-					       cur_field, index, NULL, &rec2_f_len);
+		rec1_b_ptr = rec_get_nth_field(rec1, offsets1,
+					       cur_field, &rec1_f_len);
+		rec2_b_ptr = rec_get_nth_field(rec2, offsets2,
+					       cur_field, &rec2_f_len);
 
 		if (nulls_unequal
 		    && rec1_f_len == UNIV_SQL_NULL

storage/innobase/rem/rem0rec.cc

@@ -946,36 +946,28 @@ rec_get_offsets_reverse(
 		| REC_OFFS_COMPACT | any_ext;
 }
 
-/************************************************************//**
-Get the nth field from cluster index
-@return pointer of field(Maybe get the pointer of default value of dictionary) */
+/** Get the nth field from an index.
+@param[in]	rec	index record
+@param[in]	index	index
+@param[in]	offsets	rec_get_offsets(rec, index)
+@param[in]	n	field number
+@param[out]	len	length of the field in bytes, or UNIV_SQL_NULL
+@return a read-only copy of the index field */
 const byte*
 rec_get_nth_cfield(
-	const rec_t*	rec,		/*!< in: rec */
-	const ulint*	offsets,	/*!< in: array returned by rec_get_offsets() */
-	ulint			n,			/*!< in: index of the field */
-	const dict_index_t*	index,	/*!< in: dict_index of rec. 
-									If NULL, *len maybe UNIV_SQL_DEFAULT */
-	mem_heap_t*		heap,   	/*!< in: mem_heap for default value of instant added columns
-									IF NULL, return the dictionary memory directly.
-									It must be read only when heap = NULL. */
-	ulint*			len) 		/*!< out: length of the field; UNIV_SQL_NULL if SQL null */
+	const rec_t*		rec,
+	const dict_index_t*	index,
+	const ulint*		offsets,
+	ulint			n,
+	ulint*			len)
 {
-	const byte*		field;
-	ulint off = rec_get_nth_field_offs(offsets, n, len);
-	ut_ad(index || !rec_offs_nth_default(offsets, n));
+	ut_ad(rec_offs_validate(rec, index, offsets));
 
-	if (*len != UNIV_SQL_DEFAULT || !index) {
-		return rec + off;
+	if (!rec_offs_nth_default(offsets, n)) {
+		return rec_get_nth_field(rec, offsets, n, len);
 	}
 
-	field = dict_index_get_nth_field_def(index, n, len);
-	ut_ad(*len != UNIV_SQL_DEFAULT);
-	if (heap) {
-		field = static_cast<byte*>(mem_heap_dup(heap, field, *len));
-	}
-
-	return field;
+	return dict_index_get_nth_field_def(index, n, len);
 }
 
 /************************************************************//**
@@ -1847,7 +1839,7 @@ rec_copy_prefix_to_dtuple(
 		ulint		len;
 
 		field = dtuple_get_nth_field(tuple, i);
-		data = rec_get_nth_cfield(rec, offsets, i, index, NULL, &len);
+		data = rec_get_nth_field(rec, offsets, i, &len);
 
 		if (len != UNIV_SQL_NULL) {
 			dfield_set_data(field,

storage/innobase/row/row0log.cc

@@ -1619,7 +1619,7 @@ row_log_table_apply_convert_mrec(
 blob_done:
 			rw_lock_x_unlock(dict_index_get_lock(index));
 		} else {
-			data = rec_get_nth_cfield(mrec, offsets, i, index, heap, &len);
+			data = rec_get_nth_field(mrec, offsets, i, &len);
 			dfield_set_data(dfield, data, len);
 		}
 

storage/innobase/row/row0row.cc

@@ -506,10 +506,15 @@ row_build_low(
 		}
 
 		dfield_t*	dfield = dtuple_get_nth_field(row, col_no);
-
-		const byte*	field = rec_get_nth_cfield(
-			copy, offsets, i, index, heap, &len);
-
+		const void*	field = rec_get_nth_field(
+			copy, offsets, i, &len);
+		if (len == UNIV_SQL_DEFAULT) {
+			field = dict_index_get_nth_field_def(index, i, &len);
+			if (field && type != ROW_COPY_POINTERS) {
+				ut_ad(univ_is_stored(len));
+				field = mem_heap_dup(heap, field, len);
+			}
+		}
 		dfield_set_data(dfield, field, len);
 
 		if (rec_offs_nth_extern(offsets, i)) {
@@ -644,20 +649,23 @@ row_build_w_add_vcol(
 			     add_cols, add_v, col_map, ext, heap));
 }
 
-/*******************************************************************//**
-Converts an index record to a typed data tuple.
+/** Convert an index record to a data tuple.
+@tparam def whether the dict_col_t::def_val needs to be accessed
+@param[in]	rec	index record
+@param[in]	index	index
+@param[in]	offsets	rec_get_offsets(rec, index)
+@param[out]	n_ext	number of externally stored columns
+@param[in,out]	heap	memory heap for allocations
 @return index entry built; does not set info_bits, and the data fields
 in the entry will point directly to rec */
+template<bool def>
 dtuple_t*
-row_rec_to_index_entry_low(
-/*=======================*/
-	const rec_t*		rec,	/*!< in: record in the index */
-	const dict_index_t*	index,	/*!< in: index */
-	const ulint*		offsets,/*!< in: rec_get_offsets(rec, index) */
-	ulint*			n_ext,	/*!< out: number of externally
-					stored columns */
-	mem_heap_t*		heap)	/*!< in: memory heap from which
-					the memory needed is allocated */
+row_rec_to_index_entry_impl(
+	const rec_t*		rec,
+	const dict_index_t*	index,
+	const ulint*		offsets,
+	ulint*			n_ext,
+	mem_heap_t*		heap)
 {
 	dtuple_t*	entry;
 	dfield_t*	dfield;
@@ -669,6 +677,7 @@ row_rec_to_index_entry_low(
 	ut_ad(rec != NULL);
 	ut_ad(heap != NULL);
 	ut_ad(index != NULL);
+	ut_ad(def || !rec_offs_any_default(offsets));
 
 	/* Because this function may be invoked by row0merge.cc
 	on a record whose header is in different format, the check
@@ -693,7 +702,9 @@ row_rec_to_index_entry_low(
 	for (i = 0; i < rec_len; i++) {
 
 		dfield = dtuple_get_nth_field(entry, i);
-		field = rec_get_nth_cfield(rec, offsets, i, index, heap, &len);
+		field = def
+			? rec_get_nth_cfield(rec, index, offsets, i, &len)
+			: rec_get_nth_field(rec, offsets, i, &len);
 
 		dfield_set_data(dfield, field, len);
 
@@ -704,10 +715,27 @@ row_rec_to_index_entry_low(
 	}
 
 	ut_ad(dtuple_check_typed(entry));
-
 	return(entry);
 }
 
+/** Convert an index record to a data tuple.
+@param[in]	rec	index record
+@param[in]	index	index
+@param[in]	offsets	rec_get_offsets(rec, index)
+@param[out]	n_ext	number of externally stored columns
+@param[in,out]	heap	memory heap for allocations */
+dtuple_t*
+row_rec_to_index_entry_low(
+	const rec_t*		rec,
+	const dict_index_t*	index,
+	const ulint*		offsets,
+	ulint*			n_ext,
+	mem_heap_t*		heap)
+{
+	return row_rec_to_index_entry_impl<false>(
+		rec, index, offsets, n_ext, heap);
+}
+
 /*******************************************************************//**
 Converts an index record to a typed data tuple. NOTE that externally
 stored (often big) fields are NOT copied to heap.
@@ -740,7 +768,7 @@ row_rec_to_index_entry(
 
 	rec_offs_make_valid(copy_rec, index, true,
 			    const_cast<ulint*>(offsets));
-	entry = row_rec_to_index_entry_low(
+	entry = row_rec_to_index_entry_impl<true>(
 		copy_rec, index, offsets, n_ext, heap);
 	rec_offs_make_valid(rec, index, true,
 			    const_cast<ulint*>(offsets));

storage/innobase/row/row0sel.cc

@@ -242,9 +242,9 @@ row_sel_sec_rec_is_for_clust_rec(
 			clust_field = static_cast<byte*>(vfield->data);
 		} else {
 			clust_pos = dict_col_get_clust_pos(col, clust_index);
-
-			clust_field = rec_get_nth_cfield(
-				clust_rec, clust_offs, clust_pos, clust_index, heap, &clust_len);
+			ut_ad(!rec_offs_nth_default(clust_offs, clust_pos));
+			clust_field = rec_get_nth_field(
+				clust_rec, clust_offs, clust_pos, &clust_len);
 		}
 
 		sec_field = rec_get_nth_field(sec_rec, sec_offs, i, &sec_len);
@@ -517,7 +517,6 @@ row_sel_fetch_columns(
 					rec, offsets,
 					dict_table_page_size(index->table),
 					field_no, &len, heap);
-				//field_no, &len, heap, NULL);
 
 				/* data == NULL means that the
 				externally stored field was not
@@ -534,14 +533,9 @@ row_sel_fetch_columns(
 
 				needs_copy = TRUE;
 			} else {
-
-				data = rec_get_nth_cfield(rec, offsets,
-							 field_no, index, heap, &len);
-				if (rec_offs_nth_default(offsets, field_no)) {
-					needs_copy = TRUE;
-				} else {
-					needs_copy = column->copy_val;
-				}
+				data = rec_get_nth_cfield(rec, index, offsets,
+							  field_no, &len);
+				needs_copy = column->copy_val;
 			}
 
 			if (needs_copy) {
@@ -3056,22 +3050,17 @@ row_sel_store_mysql_field_func(
 			mem_heap_free(heap);
 		}
 	} else {
-		/* Field is stored in the row. */
+		/* The field is stored in the index record, or
+		in the 'default row' for instant ADD COLUMN. */
 
 		if (rec_offs_nth_default(offsets, field_no)) {
-			/* There is default value of added column only in 
-				cluster index */
-			const dict_index_t* clust_index = 
-				dict_table_get_first_index(prebuilt->index->table); 
-
-			/* Reuse the blob_heap for instant added columns */
-			if (prebuilt->blob_heap == NULL) {
-				prebuilt->blob_heap = mem_heap_create(
-					UNIV_PAGE_SIZE);
-			}
-
-			data = rec_get_nth_cfield(rec, offsets, field_no, clust_index, 
-						prebuilt->blob_heap, &len);
+			ut_ad(dict_index_is_clust(index));
+			ut_ad(index->is_instant());
+			const dict_index_t* clust_index
+				= dict_table_get_first_index(prebuilt->table);
+			ut_ad(index == clust_index);
+			data = dict_index_get_nth_field_def(
+				clust_index, field_no, &len);
 		} else {
 			data = rec_get_nth_field(rec, offsets, field_no, &len);
 		}
@@ -4042,6 +4031,8 @@ row_sel_fill_vrow(
 
 	ut_ad(!(*vrow));
 	ut_ad(heap);
+	ut_ad(!dict_index_is_clust(index));
+	ut_ad(!index->is_instant());
 	ut_ad(page_rec_is_leaf(rec));
 
 	offsets = rec_get_offsets(rec, index, offsets, true,
@@ -4064,7 +4055,7 @@ row_sel_fill_vrow(
 			const byte*     data;
 			ulint           len;
 
-			data = rec_get_nth_cfield(rec, offsets, i, index, heap, &len);
+			data = rec_get_nth_field(rec, offsets, i, &len);
 
 			const dict_v_col_t*     vcol = reinterpret_cast<
 				const dict_v_col_t*>(col);

storage/innobase/row/row0upd.cc

@@ -1098,9 +1098,7 @@ row_upd_build_difference_binary(
 	}
 
 	for (i = 0; i < n_fld; i++) {
-
-		/* data is read only, heap can be NULL */
-		data = rec_get_nth_cfield(rec, offsets, i, index, NULL, &len);
+		data = rec_get_nth_cfield(rec, index, offsets, i, &len);
 
 		dfield = dtuple_get_nth_field(entry, i);
 
@@ -2072,14 +2070,15 @@ row_upd_copy_columns(
 	sym_node_t*	column)	/*!< in: first column in a column list, or
 				NULL */
 {
+	ut_ad(dict_index_is_clust(index));
+
 	const byte*	data;
 	ulint	len;
 
 	while (column) {
-		data = rec_get_nth_cfield(rec, offsets,
-					 column->field_nos[SYM_CLUST_FIELD_NO],
-					 index, NULL,
-					 &len);
+		data = rec_get_nth_cfield(
+			rec, index, offsets,
+			column->field_nos[SYM_CLUST_FIELD_NO], &len);
 		eval_node_copy_and_alloc_val(column, data, len);
 
 		column = UT_LIST_GET_NEXT(col_var_list, column);

storage/innobase/trx/trx0rec.cc

@@ -1091,8 +1091,8 @@ trx_undo_page_report_modify(
 						flen, max_v_log_len);
 				}
 			} else {
-				field = rec_get_nth_cfield(rec, offsets,
-							  pos, index, NULL, &flen);
+				field = rec_get_nth_cfield(
+					rec, index, offsets, pos, &flen);
 			}
 
 			if (trx_undo_left(undo_page, ptr) < 15) {
@@ -1232,8 +1232,8 @@ trx_undo_page_report_modify(
 				ptr += mach_write_compressed(ptr, pos);
 
 				/* Save the old value of field */
-				field = rec_get_nth_cfield(rec, offsets, pos,
-							  index, NULL, &flen);
+				field = rec_get_nth_cfield(
+					rec, index, offsets, pos, &flen);
 
 				if (rec_offs_nth_extern(offsets, pos)) {
 					const dict_col_t*	col =