MDEV-18720 Assertion `inited==NONE' failed in ha_index_init upon update on...

MDEV-18720 Assertion `inited==NONE' failed in ha_index_init upon update on versioned table with key on blob

* update system versioning fields before generaled columns
* don't presume that ha_write_row() means INSERT. It could still be UPDATE
* use the correct handler in check_duplicate_long_entry_key()

mysql-test/main/long_unique_bugs.result

@@ -33,3 +33,19 @@ Warnings:
 Warning	1265	Data truncated for column 't' at row 1
 Warning	1265	Data truncated for column 't' at row 2
 drop table t1;
+create table t1 ( pk int, f text, primary key (pk), unique(f)) with system versioning;
+insert into t1 values (1,'foo');
+update t1 set f = 'bar';
+select * from t1;
+pk	f
+1	bar
+update t1 set f = 'foo';
+select * from t1;
+pk	f
+1	foo
+select pk, f, row_end > DATE'2030-01-01' from t1 for system_time all;
+pk	f	row_end > DATE'2030-01-01'
+1	foo	1
+1	foo	0
+1	bar	0
+drop table t1;

mysql-test/main/long_unique_bugs.test

@@ -44,3 +44,15 @@ create table t1 (t time, unique(t)) engine=innodb;
 insert into t1 values (null),(null);
 alter ignore table t1 modify t text not null default '';
 drop table t1;
+
+#
+# MDEV-18720 Assertion `inited==NONE' failed in ha_index_init upon update on versioned table with key on blob
+#
+create table t1 ( pk int, f text, primary key (pk), unique(f)) with system versioning;
+insert into t1 values (1,'foo');
+update t1 set f = 'bar';
+select * from t1;
+update t1 set f = 'foo';
+select * from t1;
+select pk, f, row_end > DATE'2030-01-01' from t1 for system_time all;
+drop table t1;

sql/handler.cc

@@ -6548,7 +6548,7 @@ static int check_duplicate_long_entry_key(TABLE *table, handler *h,
         }
       }
     }
-    while (!is_same && !(result= table->file->ha_index_next_same(table->check_unique_buf,
+    while (!is_same && !(result= h->ha_index_next_same(table->check_unique_buf,
                          ptr, key_info->key_length)));
     if (is_same)
       error= HA_ERR_FOUND_DUPP_KEY;
@@ -6651,9 +6651,12 @@ int handler::ha_write_row(uchar *buf)
   mark_trx_read_write();
   increment_statistics(&SSV::ha_write_count);
 
-  if (table->s->long_unique_table &&
-          (error= check_duplicate_long_entries(table, table->file, buf)))
+  if (table->s->long_unique_table)
+  {
+    handler *h= table->update_handler ? table->update_handler : table->file;
+    if ((error= check_duplicate_long_entries(table, h, buf)))
       DBUG_RETURN(error);
+  }
   TABLE_IO_WAIT(tracker, m_psi, PSI_TABLE_WRITE_ROW, MAX_KEY, 0,
                       { error= write_row(buf); })
 

sql/sql_base.cc

@@ -8698,11 +8698,11 @@ fill_record(THD *thd, TABLE *table, Field **ptr, List<Item> &values,
     goto err;
   /* Update virtual fields */
   thd->abort_on_warning= FALSE;
+  if (table->versioned())
+    table->vers_update_fields();
   if (table->vfield &&
       table->update_virtual_fields(table->file, VCOL_UPDATE_FOR_WRITE))
     goto err;
-  if (table->versioned())
-    table->vers_update_fields();
   thd->abort_on_warning= abort_on_warning_saved;
   DBUG_RETURN(thd->is_error());