bugfix: mark_columns_needed_for_update

cannot use TABLE:merge_keys for that, because Field::part_of_key
was designed to mark fields for KEY_READ, so a field is not a
"part of key", if only prefix of the field is.

mysql-test/include/commit.inc

@@ -430,9 +430,9 @@ call p_verify_status_increment(2, 2, 2, 2);
 --echo # 4. Read-write statement: UPDATE, update 0 rows, 1 row matches WHERE 
 --echo #
 update t1 set a=2;
-call p_verify_status_increment(2, 2, 1, 0);
+call p_verify_status_increment(2, 0, 1, 0);
 commit;
-call p_verify_status_increment(2, 2, 1, 0);
+call p_verify_status_increment(2, 0, 1, 0);
 
 --echo # 5. Read-write statement: UPDATE, update 0 rows, 0 rows match WHERE 
 --echo #

mysql-test/r/commit_1innodb.result

@@ -419,11 +419,11 @@ SUCCESS
 # 4. Read-write statement: UPDATE, update 0 rows, 1 row matches WHERE 
 #
 update t1 set a=2;
-call p_verify_status_increment(2, 2, 1, 0);
+call p_verify_status_increment(2, 0, 1, 0);
 SUCCESS
 
 commit;
-call p_verify_status_increment(2, 2, 1, 0);
+call p_verify_status_increment(2, 0, 1, 0);
 SUCCESS
 
 # 5. Read-write statement: UPDATE, update 0 rows, 0 rows match WHERE 

mysql-test/suite/vcol/r/update.result

@@ -8,3 +8,30 @@ select * from t1;
 a	b	c
 2	3	4
 drop table t1;
+create table t1 (a int, c int as(a), p varchar(20) as(y), y char(20), index (p,c));
+insert into t1 (a,y) values(1, "yyy");
+update t1 set a = 100 where a = 1;
+drop table t1;
+create table t1 (
+a varchar(10000),
+b varchar(3000),
+c varchar(14000) generated always as (concat(a,b)) virtual,
+d varchar(5000) generated always as (b) virtual,
+e int(11) generated always as (10) virtual,
+h int(11) not null primary key,
+index(c(100), d(20)));
+insert t1 (a,b,h) values (repeat('g', 10000), repeat('x', 2800), 1);
+update t1 set a = repeat(cast(1 as char), 2000);
+drop table t1;
+create table t1 (
+a varchar(10000),
+b varchar(3000),
+c varchar(14000) generated always as (concat(a,b)) virtual,
+i varchar(5000) generated always as (b) virtual,
+d varchar(5000) generated always as (i) virtual,
+e int(11) generated always as (10) virtual,
+h int(11) not null primary key,
+index(c(100), d(20)));
+insert t1 (a,b,h) values (repeat('g', 10000), repeat('x', 2800), 1);
+update t1 set a = repeat(cast(1 as char), 2000);
+drop table t1;

mysql-test/suite/vcol/t/update.test

@@ -10,3 +10,39 @@ select * from t1;
 update t1 set a=2;
 select * from t1;
 drop table t1;
+#
+# one keypart is virtual, the other keypart is updated
+# this tests TABLE::mark_columns_needed_for_update()
+#
+create table t1 (a int, c int as(a), p varchar(20) as(y), y char(20), index (p,c));
+insert into t1 (a,y) values(1, "yyy");
+update t1 set a = 100 where a = 1;
+drop table t1;
+
+#
+# note: prefix keys below
+#
+create table t1 (
+  a varchar(10000),
+  b varchar(3000),
+  c varchar(14000) generated always as (concat(a,b)) virtual,
+  d varchar(5000) generated always as (b) virtual,
+  e int(11) generated always as (10) virtual,
+  h int(11) not null primary key,
+  index(c(100), d(20)));
+insert t1 (a,b,h) values (repeat('g', 10000), repeat('x', 2800), 1);
+update t1 set a = repeat(cast(1 as char), 2000);
+drop table t1;
+
+create table t1 (
+  a varchar(10000),
+  b varchar(3000),
+  c varchar(14000) generated always as (concat(a,b)) virtual,
+  i varchar(5000) generated always as (b) virtual,
+  d varchar(5000) generated always as (i) virtual,
+  e int(11) generated always as (10) virtual,
+  h int(11) not null primary key,
+  index(c(100), d(20)));
+insert t1 (a,b,h) values (repeat('g', 10000), repeat('x', 2800), 1);
+update t1 set a = repeat(cast(1 as char), 2000);
+drop table t1;

sql/table.cc

@@ -6272,15 +6272,34 @@ void TABLE::mark_columns_needed_for_update()
 
   if (triggers)
     triggers->mark_fields_used(TRG_EVENT_UPDATE);
+  if (default_field)
+    mark_default_fields_for_write(FALSE);
+  if (vfield)
+    need_signal|= mark_virtual_columns_for_write(FALSE);
   if (file->ha_table_flags() & HA_REQUIRES_KEY_COLUMNS_FOR_DELETE)
   {
-    /* Mark all used key columns for read */
-    Field **reg_field;
-    for (reg_field= field ; *reg_field ; reg_field++)
+    KEY *end= key_info + s->keys;
+    for (KEY *k= key_info; k < end; k++)
     {
-      /* Merge keys is all keys that had a column refered to in the query */
-      if (merge_keys.is_overlapping((*reg_field)->part_of_key))
-        bitmap_set_bit(read_set, (*reg_field)->field_index);
+      KEY_PART_INFO *kpend= k->key_part + k->ext_key_parts;
+      bool any_written= false, all_read= true;
+      for (KEY_PART_INFO *kp= k->key_part; kp < kpend; kp++)
+      {
+        int idx= kp->fieldnr - 1;
+        any_written|= bitmap_is_set(write_set, idx);
+        all_read&= bitmap_is_set(read_set, idx);
+      }
+      if (any_written && !all_read)
+      {
+        for (KEY_PART_INFO *kp= k->key_part; kp < kpend; kp++)
+        {
+          int idx= kp->fieldnr - 1;
+          if (bitmap_fast_test_and_set(read_set, idx))
+            continue;
+          if (field[idx]->vcol_info)
+            mark_virtual_col(field[idx]);
+        }
+      }
     }
     need_signal= true;
   }
@@ -6299,11 +6318,6 @@ void TABLE::mark_columns_needed_for_update()
       need_signal= true;
     }
   }
-  if (default_field)
-    mark_default_fields_for_write(FALSE);
-  /* Mark all virtual columns needed for update */
-  if (vfield)
-    need_signal|= mark_virtual_columns_for_write(FALSE);
   if (check_constraints)
   {
     mark_check_constraint_columns_for_read();