BUG#27016053: REGRESSION IN BINLOG_LOG_ROW INTRODUCED BY ADD_PKE

Group Replication plugin is a multi or single primary replication
solution, on which members do execute transactions optimistically
and at commit time they decide, if conflicts happen, which must
commit or rollback.
The conflict detection is based on the write-sets of each
transaction, which is collected along the transaction life when it
does a update.
During detailed performance analysis it was discovered that there
were non-optimized memory allocations and memory copy operations on
the write-set extraction.

In order to solve the performance regression, the following actions
were made:
 1) optimize memory allocation;
 2) reduce memory copy operations;
 3) only collect foreign key write-sets when the current table has
    foreign keys.

Author: nacarvalho

mysql-test/suite/rpl/r/rpl_transaction_write_set_extraction.result

@@ -5,7 +5,7 @@ Note	####	Storing MySQL user name or password information in the master info rep
 [connection master]
 include/assert.inc [The value for transaction_write_set_extraction must be XXHASH64]
 CREATE TABLE t1 (a BINARY(1) PRIMARY KEY);
-SET @@GLOBAL.DEBUG= @debug_saved;
+SET @debug_saved= @@GLOBAL.DEBUG;
 SET @@GLOBAL.DEBUG= '+d,PKE_assert_single_primary_key_generated_insert';
 INSERT INTO t1 VALUES(1);
 SET @@GLOBAL.DEBUG= @debug_saved;

mysql-test/suite/rpl/t/rpl_transaction_write_set_extraction.test

@@ -17,7 +17,7 @@
 
 --connection master
 CREATE TABLE t1 (a BINARY(1) PRIMARY KEY);
-SET @@GLOBAL.DEBUG= @debug_saved;
+SET @debug_saved= @@GLOBAL.DEBUG;
 SET @@GLOBAL.DEBUG= '+d,PKE_assert_single_primary_key_generated_insert';
 INSERT INTO t1 VALUES(1);
 SET @@GLOBAL.DEBUG= @debug_saved;

sql/handler.cc

@@ -8260,7 +8260,6 @@ int binlog_log_row(TABLE* table,
   {
     if (thd->variables.transaction_write_set_extraction != HASH_ALGORITHM_OFF)
     {
-      bitmap_set_all(table->read_set);
       if (before_record && after_record)
       {
         size_t length= table->s->reclength;

sql/rpl_transaction_write_set_ctx.cc

@@ -1,4 +1,4 @@
-/* Copyright (c) 2014, 2017, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License, version 2.0,
@@ -43,6 +43,13 @@ Rpl_transaction_write_set_ctx::Rpl_transaction_write_set_ctx():
   m_has_missing_keys(false), m_has_related_foreign_keys(false)
 {
   DBUG_ENTER("Rpl_transaction_write_set_ctx::Rpl_transaction_write_set_ctx");
+  /*
+    In order to speed-up small transactions write-set extraction,
+    we preallocate 12 elements.
+    12 is a sufficient number to hold write-sets for single
+    statement transactions, even on tables with foreign keys.
+  */
+  write_set.reserve(12);
   DBUG_VOID_RETURN;
 }