branches/5.1: When converting a record to MySQL format, copy the default

column values for columns that are SQL NULL.  This addresses failures in
row-based replication (Bug #39648).

row_prebuilt_t: Add default_rec, for the default values of the columns in
MySQL format.

row_sel_store_mysql_rec(): Use prebuilt->default_rec instead of
padding columns.

rb://64 approved by Heikki Tuuri

handler/ha_innodb.cc

@@ -2508,6 +2508,8 @@ ha_innobase::open(
 	prebuilt = row_create_prebuilt(ib_table);
 
 	prebuilt->mysql_row_len = table->s->reclength;
+	prebuilt->default_rec = table->s->default_values;
+	ut_ad(prebuilt->default_rec);
 
 	/* Looks like MySQL-3.23 sometimes has primary key number != 0 */
 

include/row0mysql.h

@@ -594,6 +594,8 @@ struct row_prebuilt_struct {
 	byte*		ins_upd_rec_buff;/* buffer for storing data converted
 					to the Innobase format from the MySQL
 					format */
+	const byte*	default_rec;	/* the default values of all columns
+					(a "default row") in MySQL format */
 	ulint		hint_need_to_fetch_extra_cols;
 					/* normally this is set to 0; if this
 					is set to ROW_RETRIEVE_PRIMARY_KEY,

row/row0mysql.c

@@ -620,6 +620,7 @@ row_create_prebuilt(
 	prebuilt->ins_node = NULL;
 
 	prebuilt->ins_upd_rec_buff = NULL;
+	prebuilt->default_rec = NULL;
 
 	prebuilt->upd_node = NULL;
 	prebuilt->ins_graph = NULL;

row/row0sel.c

@@ -2597,6 +2597,7 @@ row_sel_store_mysql_rec(
 	ulint			i;
 
 	ut_ad(prebuilt->mysql_template);
+	ut_ad(prebuilt->default_rec);
 	ut_ad(rec_offs_validate(rec, NULL, offsets));
 
 	if (UNIV_LIKELY_NULL(prebuilt->blob_heap)) {
@@ -2683,58 +2684,14 @@ row_sel_store_mysql_rec(
 					&= ~(byte) templ->mysql_null_bit_mask;
 			}
 		} else {
-			/* MySQL seems to assume the field for an SQL NULL
-			value is set to zero or space. Not taking this into
-			account caused seg faults with NULL BLOB fields, and
-			bug number 154 in the MySQL bug database: GROUP BY
-			and DISTINCT could treat NULL values inequal. */
-			int	pad_char;
+			/* MySQL assumes that the field for an SQL
+			NULL value is set to the default value. */
 
 			mysql_rec[templ->mysql_null_byte_offset]
 				|= (byte) templ->mysql_null_bit_mask;
-			switch (templ->type) {
-			case DATA_VARCHAR:
-			case DATA_BINARY:
-			case DATA_VARMYSQL:
-				if (templ->mysql_type
-				    == DATA_MYSQL_TRUE_VARCHAR) {
-					/* This is a >= 5.0.3 type
-					true VARCHAR.  Zero the field. */
-					pad_char = 0x00;
-					break;
-				}
-				/* Fall through */
-			case DATA_CHAR:
-			case DATA_FIXBINARY:
-			case DATA_MYSQL:
-				/* MySQL pads all string types (except
-				BLOB, TEXT and true VARCHAR) with space. */
-				if (UNIV_UNLIKELY(templ->mbminlen == 2)) {
-					/* Treat UCS2 as a special case. */
-					data = mysql_rec
-						+ templ->mysql_col_offset;
-					len = templ->mysql_col_len;
-					/* There are two UCS2 bytes per char,
-					so the length has to be even. */
-					ut_a(!(len & 1));
-					/* Pad with 0x0020. */
-					while (len) {
-						*data++ = 0x00;
-						*data++ = 0x20;
-						len -= 2;
-					}
-					continue;
-				}
-				pad_char = 0x20;
-				break;
-			default:
-				pad_char = 0x00;
-				break;
-			}
-
-			ut_ad(!pad_char || templ->mbminlen == 1);
-			memset(mysql_rec + templ->mysql_col_offset,
-			       pad_char, templ->mysql_col_len);
+			memcpy(mysql_rec + templ->mysql_col_offset,
+			       prebuilt->default_rec + templ->mysql_col_offset,
+			       templ->mysql_col_len);
 		}
 	}