Making DROP TABLE IF EXISTS, DROP DATABASE IF EXISTS, DELETE FROM, UPDATE be logged to

binlog even if they changed nothing, and a test for this.
This is useful when users use these commands to clean up their master and slave by issuing
one command on master (assume master and slave have slightly different data for some
reason and you want to clean up both).
Note that I have not changed multi-table DELETE and multi-table UPDATE because their
error-reporting mechanism is more complicated.


mysql-test/r/mysqlbinlog.result:
  result update
mysql-test/r/rpl_charset.result:
  result update
mysql-test/r/rpl_flush_log_loop.result:
  result update
mysql-test/r/rpl_replicate_do.result:
  result update
mysql-test/r/rpl_temporary.result:
  result update
mysql-test/t/mysqlbinlog.test:
  moving SET TIMESTAMP up as DROP shows up in binlog
sql/sql_db.cc:
  DROP DATABASE IF EXISTS is now always logged to binlog, even if db did not exist
sql/sql_delete.cc:
  DELETE FROM t is now always logged to binlog even if no rows deleted (but in this case, only if really no error).
sql/sql_table.cc:
  DROP TABLE IF EXISTS is now always logged to binlog even if table did not exist
sql/sql_update.cc:
  UPDATE is now always logged to binlog even if no rows updated (but in this case, only if really no error).

1 files changed, 11 insertions, 1 deletions

diff --git a/sql/sql_delete.cc b/sql/sql_delete.cc
index f21dbb10712..48497636186 100644
--- a/sql/sql_delete.cc
+++ b/sql/sql_delete.cc
@@ -199,7 +199,15 @@ cleanup:
 
   transactional_table= table->file->has_transactions();
   log_delayed= (transactional_table || table->tmp_table);
-  if (deleted && (error <= 0 || !transactional_table))
+  /*
+    We write to the binary log even if we deleted no row, because maybe the
+    user is using this command to ensure that a table is clean on master *and
+    on slave*. Think of the case of a user having played separately with the
+    master's table and slave's table and wanting to take a fresh identical
+    start now.
+    error < 0 means "really no error". error <= 0 means "maybe some error".
+  */
+  if ((deleted || (error < 0)) && (error <= 0 || !transactional_table))
   {
     mysql_update_log.write(thd,thd->query, thd->query_length);
     if (mysql_bin_log.is_open())
@@ -544,6 +552,8 @@ bool multi_delete::send_eof()
     rows and we succeeded, or also in an error case when there
     was a non-transaction-safe table involved, since
     modifications in it cannot be rolled back.
+    Note that if we deleted nothing we don't write to the binlog (TODO:
+    fix this).
   */
   if (deleted && (error <= 0 || normal_tables))
   {