MDEV-26866 FOREIGN KEY…SET NULL corrupts an index on a virtual column

The initial test case for MySQL Bug #33053297 is based on
mysql/mysql-server@27130e25078864b010d81266f9613d389d4a229b.

innobase_get_field_from_update_vector is not a suitable function to fetch
updated row info, as well as parent table's update vector is not always
suitable. For instance, in case of DELETE it contains undefined data.

castade->update vector seems to be good enough to fetch all base columns
update data, and besides faster, and less error-prone.

1 files changed, 13 insertions, 51 deletions

diff --git a/storage/innobase/handler/ha_innodb.cc b/storage/innobase/handler/ha_innodb.cc
index 91d245ad0e2..37748cb497a 100644
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -21795,48 +21795,6 @@ innobase_rename_vc_templ(
 	table->vc_templ->tb_name = t_tbname;
 }
 
-/** Get the updated parent field value from the update vector for the
-given col_no.
-@param[in]	foreign		foreign key information
-@param[in]	update		updated parent vector.
-@param[in]	col_no		base column position of the child table to check
-@return updated field from the parent update vector, else NULL */
-static
-dfield_t*
-innobase_get_field_from_update_vector(
-	dict_foreign_t*	foreign,
-	upd_t*		update,
-	ulint		col_no)
-{
-	dict_table_t*	parent_table = foreign->referenced_table;
-	dict_index_t*	parent_index = foreign->referenced_index;
-	ulint		parent_field_no;
-	ulint		parent_col_no;
-	ulint		prefix_col_no;
-
-	for (ulint i = 0; i < foreign->n_fields; i++) {
-		if (dict_index_get_nth_col_no(foreign->foreign_index, i)
-		    != col_no) {
-			continue;
-		}
-
-		parent_col_no = dict_index_get_nth_col_no(parent_index, i);
-		parent_field_no = dict_table_get_nth_col_pos(
-			parent_table, parent_col_no, &prefix_col_no);
-
-		for (ulint j = 0; j < update->n_fields; j++) {
-			upd_field_t*	parent_ufield
-				= &update->fields[j];
-
-			if (parent_ufield->field_no == parent_field_no) {
-				return(&parent_ufield->new_val);
-			}
-		}
-	}
-
-	return (NULL);
-}
-
 
 /**
    Allocate a heap and record for calculating virtual fields
@@ -21919,9 +21877,10 @@ void innobase_report_computed_value_failed(dtuple_t *row)
 @param[in]	ifield		index field
 @param[in]	thd		MySQL thread handle
 @param[in,out]	mysql_table	mysql table object
+@param[in,out]	mysql_rec	MariaDB record buffer
 @param[in]	old_table	during ALTER TABLE, this is the old table
 				or NULL.
-@param[in]	parent_update	update vector for the parent row
+@param[in]	update		update vector for the row, if any
 @param[in]	foreign		foreign key information
 @return the field filled with computed value, or NULL if just want
 to store the value in passed in "my_rec" */
@@ -21937,8 +21896,7 @@ innobase_get_computed_value(
 	TABLE*			mysql_table,
 	byte*			mysql_rec,
 	const dict_table_t*	old_table,
-	upd_t*			parent_update,
-	dict_foreign_t*		foreign)
+	const upd_t*		update)
 {
 	byte		rec_buf2[REC_VERSION_56_MAX_INDEX_COL_LEN];
 	byte*		buf;
@@ -21951,6 +21909,8 @@ innobase_get_computed_value(
 
 	ulint		ret = 0;
 
+	dict_index_t *clust_index= dict_table_get_first_index(index->table);
+
 	ut_ad(index->table->vc_templ);
 	ut_ad(thd != NULL);
 	ut_ad(mysql_table);
@@ -21980,14 +21940,16 @@ innobase_get_computed_value(
 			= index->table->vc_templ->vtempl[col_no];
 		const byte*			data;
 
-		if (parent_update != NULL) {
-			/** Get the updated field from update vector
-			of the parent table. */
-			row_field = innobase_get_field_from_update_vector(
-					foreign, parent_update, col_no);
+		if (update) {
+			ulint clust_no = dict_col_get_clust_pos(base_col,
+								clust_index);
+			if (const upd_field_t *uf = upd_get_field_by_field_no(
+				    update, clust_no, false)) {
+				row_field = &uf->new_val;
+			}
 		}
 
-		if (row_field == NULL) {
+		if (!row_field) {
 			row_field = dtuple_get_nth_field(row, col_no);
 		}