MDEV-17614 INSERT on dup key update is replication unsafe

Problem:-
When mysql executes INSERT ON DUPLICATE KEY INSERT, the storage engine checks
if the inserted row would generate a duplicate key error. If yes, it returns
the existing row to mysql, mysql updates it and sends it back to the storage
engine.When the table has more than one unique or primary key, this statement
is sensitive to the order in which the storage engines checks the keys.
Depending on this order, the storage engine may determine different rows
to mysql, and hence mysql can update different rows.The order that the
storage engine checks keys is not deterministic. For example, InnoDB checks
keys in an order that depends on the order in which indexes were added to
the table. The first added index is checked first. So if master and slave
have added indexes in different orders, then slave may go out of sync.

Solution:-
Make INSERT...ON DUPLICATE KEY UPDATE unsafe while using stmt or mixed format
When there is more then one unique key.
Although there is two exception.
  1. Auto Increment key is not counted because Innodb will get gap lock for
    failed Insert and concurrent insert will get a next increment value. But if
    user supplies auto inc value it can be unsafe.
  2. Count only unique keys for which insertion is performed.

So this patch also addresses the bug id #72921

1 files changed, 42 insertions, 0 deletions

diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index 6bcff6d1fca..1a3ca54abf8 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -6144,6 +6144,48 @@ int THD::decide_logging_format(TABLE_LIST *tables)
   DBUG_RETURN(0);
 }
 
+int THD::decide_logging_format_low(TABLE *table)
+{
+  /*
+   INSERT...ON DUPLICATE KEY UPDATE on a table with more than one unique keys
+   can be unsafe.
+   */
+  if(wsrep_binlog_format() <= BINLOG_FORMAT_STMT &&
+       !is_current_stmt_binlog_format_row() &&
+       !lex->is_stmt_unsafe() &&
+       lex->sql_command == SQLCOM_INSERT &&
+       lex->duplicates == DUP_UPDATE)
+  {
+    uint unique_keys= 0;
+    uint keys= table->s->keys, i= 0;
+    Field *field;
+    for (KEY* keyinfo= table->s->key_info;
+             i < keys && unique_keys <= 1; i++, keyinfo++)
+      if (keyinfo->flags & HA_NOSAME &&
+         !(keyinfo->key_part->field->flags & AUTO_INCREMENT_FLAG &&
+             //User given auto inc can be unsafe
+             !keyinfo->key_part->field->val_int()))
+      {
+        for (uint j= 0; j < keyinfo->user_defined_key_parts; j++)
+        {
+          field= keyinfo->key_part[j].field;
+          if(!bitmap_is_set(table->write_set,field->field_index))
+            goto exit;
+        }
+        unique_keys++;
+exit:;
+      }
+
+    if (unique_keys > 1)
+    {
+      lex->set_stmt_unsafe(LEX::BINLOG_STMT_UNSAFE_INSERT_TWO_KEYS);
+      binlog_unsafe_warning_flags|= lex->get_stmt_unsafe_flags();
+      set_current_stmt_binlog_format_row_if_mixed();
+      return 1;
+    }
+  }
+  return 0;
+}
 
 /*
   Implementation of interface to write rows to the binary log through the