branches/zip: Fix a bug in the updates of index records that contain a

column prefix of an externally stored column.

row_upd_ext_fetch(): New function.

row_upd_index_replace_new_col_vals(),
row_upd_index_replace_new_col_vals_index_pos(): Fetch prefixes of
externally stored columns when they are needed for column prefix
indexes.  For memory allocation, add the parameter ext_heap.  Avoid
repeating the inner loop after finding a  matching upd_field->field_no.

btr/btr0cur.c

@@ -1860,7 +1860,7 @@ btr_cur_optimistic_update(
 	ut_a(!n_ext);
 
 	row_upd_index_replace_new_col_vals_index_pos(new_entry, index, update,
-						     FALSE, NULL);
+						     FALSE, NULL, heap);
 	old_rec_size = rec_offs_size(offsets);
 	new_rec_size = rec_get_converted_size(index, new_entry, 0);
 
@@ -2131,7 +2131,7 @@ btr_cur_pessimistic_update(
 	rec_offs_make_valid(rec, index, offsets);
 
 	row_upd_index_replace_new_col_vals_index_pos(new_entry, index, update,
-						     FALSE, *heap);
+						     FALSE, *heap, *heap);
 	if (!(flags & BTR_KEEP_SYS_FLAG)) {
 		row_upd_index_entry_sys_field(new_entry, index, DATA_ROLL_PTR,
 					      roll_ptr);

include/row0upd.h

@@ -195,9 +195,14 @@ row_upd_index_replace_new_col_vals_index_pos(
 				/* in: if TRUE, limit the replacement to
 				ordering fields of index; note that this
 				does not work for non-clustered indexes. */
-	mem_heap_t*	heap);	/* in: memory heap to which we allocate and
+	mem_heap_t*	heap,	/* in: memory heap to which we allocate and
 				copy the new values, set this as NULL if you
 				do not want allocation */
+	mem_heap_t*	ext_heap);/* in: memory heap where to allocate
+				column prefixes of externally stored
+				columns, may be NULL if the index
+				record does not contain externally
+				stored columns or column prefixes */
 /***************************************************************
 Replaces the new column values stored in the update vector to the index entry
 given. */
@@ -211,9 +216,14 @@ row_upd_index_replace_new_col_vals(
 	const upd_t*	update,	/* in: an update vector built for the
 				CLUSTERED index so that the field number in
 				an upd_field is the clustered index position */
-	mem_heap_t*	heap);	/* in: memory heap to which we allocate and
+	mem_heap_t*	heap,	/* in: memory heap to which we allocate and
 				copy the new values, set this as NULL if you
 				do not want allocation */
+	mem_heap_t*	ext_heap);/* in: memory heap where to allocate
+				column prefixes of externally stored
+				columns, may be NULL if the index
+				record does not contain externally
+				stored columns or column prefixes */
 /***************************************************************
 Checks if an update vector changes an ordering field of an index record.
 This function is fast if the update vector is short or the number of ordering

row/row0umod.c

@@ -638,7 +638,8 @@ row_undo_mod_upd_exist_sec(
 			'abc' -> 'aBc'. */
 
 			row_upd_index_replace_new_col_vals(entry, index,
-							   node->update, NULL);
+							   node->update,
+							   NULL, heap);
 			err = row_undo_mod_del_unmark_sec_and_undo_update(
 				BTR_MODIFY_LEAF, thr, index, entry);
 			if (err == DB_FAIL) {

row/row0upd.c

@@ -832,6 +832,35 @@ row_upd_build_difference_binary(
 	return(update);
 }
 
+/***************************************************************
+Fetch a prefix of an externally stored column.  This is similar
+to row_ext_lookup(), but the row_ext_t holds the old values
+of the column and must not be poisoned with the new values. */
+static
+byte*
+row_upd_ext_fetch(
+/*==============*/
+					/* out: BLOB prefix */
+	const byte*	data,		/* in: 'internally' stored part of the
+					field containing also the reference to
+					the external part */
+	ulint		local_len,	/* in: length of data, in bytes */
+	ulint		zip_size,	/* in: nonzero=compressed BLOB
+					page size, zero for uncompressed
+					BLOBs */
+	ulint*		len,		/* in: length of prefix to fetch;
+					out: fetched length of the prefix */
+	mem_heap_t*	heap)		/* in: heap where to allocate */
+{
+	byte*	buf = mem_heap_alloc(heap, *len);
+
+	*len = btr_copy_externally_stored_field_prefix(buf, *len,
+						       zip_size,
+						       data, local_len);
+
+	return(buf);
+}
+
 /***************************************************************
 Replaces the new column values stored in the update vector to the index entry
 given. */
@@ -849,13 +878,15 @@ row_upd_index_replace_new_col_vals_index_pos(
 				/* in: if TRUE, limit the replacement to
 				ordering fields of index; note that this
 				does not work for non-clustered indexes. */
-	mem_heap_t*	heap)	/* in: memory heap to which we allocate and
+	mem_heap_t*	heap,	/* in: memory heap to which we allocate and
 				copy the new values, set this as NULL if you
 				do not want allocation */
+	mem_heap_t*	ext_heap)/* in: memory heap where to allocate
+				column prefixes of externally stored
+				columns, may be NULL if the index
+				record does not contain externally
+				stored columns or column prefixes */
 {
-	dict_field_t*	field;
-	upd_field_t*	upd_field;
-	dfield_t*	dfield;
 	ulint		j;
 	ulint		i;
 	ulint		n_fields;
@@ -872,44 +903,78 @@ row_upd_index_replace_new_col_vals_index_pos(
 
 	for (j = 0; j < n_fields; j++) {
 
-		field = dict_index_get_nth_field(index, j);
+		dict_field_t*		field
+			= dict_index_get_nth_field(index, j);
+		const dict_col_t*	col
+			= dict_field_get_col(field);
 
 		for (i = 0; i < upd_get_n_fields(update); i++) {
 
+			upd_field_t*	upd_field;
+			dfield_t*	dfield;
+
 			upd_field = upd_get_nth_field(update, i);
 
-			if (upd_field->field_no == j) {
+			if (upd_field->field_no != j) {
+				continue;
+			}
 
 			dfield = dtuple_get_nth_field(entry, j);
 
 			dfield_copy_data(dfield, &upd_field->new_val);
 
 			if (dfield_is_null(dfield)) {
-					continue;
-				}
-
-				if (heap) {
-					dfield_dup(dfield, heap);
+				break;
 			}
 
 			if (field->prefix_len > 0) {
-
-					const dict_col_t*	col
-						= dict_field_get_col(field);
 				ulint		len
 					= dfield_get_len(dfield);
+				const char*	data
+					= dfield_get_data(dfield);
+				ibool		fetch_ext
+					= dfield_is_ext(dfield)
+					&& len < field->prefix_len
+					+ BTR_EXTERN_FIELD_REF_SIZE;
+
+				if (fetch_ext) {
+					ulint	l
+						= len;
+					ulint	zip_size
+						= dict_table_zip_size(
+							index->table);
+					ut_a(ext_heap);
+
+					len = field->prefix_len;
+
+					data = row_upd_ext_fetch(data, l,
+								 zip_size,
+								 &len,
+								 ext_heap);
+				}
 
 				len = dtype_get_at_most_n_mbchars(
 					col->prtype,
 					col->mbminlen,
 					col->mbmaxlen,
 					field->prefix_len,
-						len,
-						dfield_get_data(dfield));
+					len, data);
 
-					dfield_set_len(dfield, len);
+				dfield_set_data(dfield, data, len);
+
+				if (fetch_ext && heap && heap == ext_heap) {
+					/* Skip the dfield_dup() below,
+					as the column prefix has already
+					been allocated from ext_heap. */
+					break;
+				}
 			}
+
+			if (heap) {
+				dfield_dup(dfield, heap);
 			}
+
+			break;
 		}
 	}
 }
@@ -927,12 +992,15 @@ row_upd_index_replace_new_col_vals(
 	const upd_t*	update,	/* in: an update vector built for the
 				CLUSTERED index so that the field number in
 				an upd_field is the clustered index position */
-	mem_heap_t*	heap)	/* in: memory heap to which we allocate and
+	mem_heap_t*	heap,	/* in: memory heap to which we allocate and
 				copy the new values, set this as NULL if you
 				do not want allocation */
+	mem_heap_t*	ext_heap)/* in: memory heap where to allocate
+				column prefixes of externally stored
+				columns, may be NULL if the index
+				record does not contain externally
+				stored columns or column prefixes */
 {
-	upd_field_t*	upd_field;
-	dfield_t*	dfield;
 	ulint		j;
 	ulint		i;
 	dict_index_t*	clust_index;
@@ -945,47 +1013,78 @@ row_upd_index_replace_new_col_vals(
 
 	for (j = 0; j < dict_index_get_n_fields(index); j++) {
 
-		ulint		clust_pos;
-		dict_field_t*	field = dict_index_get_nth_field(index, j);
-
-		clust_pos = dict_col_get_clust_pos(field->col, clust_index);
+		dict_field_t*		field
+			= dict_index_get_nth_field(index, j);
+		const dict_col_t*	col
+			= dict_field_get_col(field);
+		const ulint		clust_pos
+			= dict_col_get_clust_pos(col, clust_index);
 
 		for (i = 0; i < upd_get_n_fields(update); i++) {
 
+			upd_field_t*	upd_field;
+			dfield_t*	dfield;
+
 			upd_field = upd_get_nth_field(update, i);
 
-			if (upd_field->field_no == clust_pos) {
+			if (upd_field->field_no != clust_pos) {
+				continue;
+			}
 
 			dfield = dtuple_get_nth_field(entry, j);
 
 			dfield_copy_data(dfield, &upd_field->new_val);
 
 			if (dfield_is_null(dfield)) {
-					continue;
-				}
-
-				if (heap) {
-					dfield_dup(dfield, heap);
+				break;
 			}
 
 			if (field->prefix_len > 0) {
-
-					const dict_col_t*	col
-						= dict_field_get_col(field);
 				ulint		len
 					= dfield_get_len(dfield);
+				const char*	data
+					= dfield_get_data(dfield);
+
+				if (dfield_is_ext(dfield)
+				    && len < field->prefix_len
+				    + BTR_EXTERN_FIELD_REF_SIZE) {
+					ulint	l
+						= len;
+					ulint	zip_size
+						= dict_table_zip_size(
+							index->table);
+					ut_a(ext_heap);
+
+					len = field->prefix_len;
+
+					data = row_upd_ext_fetch(data, l,
+								 zip_size,
+								 &len,
+								 ext_heap);
+				}
 
 				len = dtype_get_at_most_n_mbchars(
 					col->prtype,
 					col->mbminlen,
 					col->mbmaxlen,
 					field->prefix_len,
-						len,
-						dfield_get_data(dfield));
+					len, data);
 
-					dfield_set_len(dfield, len);
+				dfield_set_data(dfield, data, len);
+
+				if (fetch_ext && heap && heap == ext_heap) {
+					/* Skip the dfield_dup() below,
+					as the column prefix has already
+					been allocated from ext_heap. */
+					break;
+				}
 			}
+
+			if (heap) {
+				dfield_dup(dfield, heap);
 			}
+
+			break;
 		}
 	}
 }
@@ -1338,7 +1437,8 @@ row_upd_sec_index_entry(
 	}
 
 	/* Build a new index entry */
-	row_upd_index_replace_new_col_vals(entry, index, node->update, NULL);
+	row_upd_index_replace_new_col_vals(entry, index, node->update,
+					   NULL, heap);
 
 	/* Insert new index entry */
 	err = row_ins_index_entry(index, entry, 0, TRUE, thr);
@@ -1458,7 +1558,8 @@ row_upd_clust_rec_by_insert(
 
 	entry = row_build_index_entry(node->row, node->ext, index, heap);
 
-	row_upd_index_replace_new_col_vals(entry, index, node->update, NULL);
+	row_upd_index_replace_new_col_vals(entry, index, node->update,
+					   NULL, heap);
 
 	row_upd_index_entry_sys_field(entry, index, DATA_TRX_ID, trx->id);
 

trx/trx0rec.c

@@ -1413,7 +1413,8 @@ trx_undo_prev_version_build(
 		entry = row_rec_to_index_entry(ROW_COPY_DATA, rec, index,
 					       offsets, &n_ext, heap);
 		n_ext += btr_push_update_extern_fields(entry, update);
-		row_upd_index_replace_new_col_vals(entry, index, update, heap);
+		row_upd_index_replace_new_col_vals(entry, index, update,
+						   heap, heap);
 
 		buf = mem_heap_alloc(heap, rec_get_converted_size(index, entry,
 								  n_ext));