Changed the default setting of the optimizer switch 'optimize_join_buffer_size'.

Made it 'off' by default.

mysql-test/r/join_cache.result

 DROP TABLE IF EXISTS t1,t2,t3,t4,t5,t6,t7,t8,t9,t10,t11;
 DROP DATABASE IF EXISTS world;
 set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch='optimize_join_buffer_size=on';
 set optimizer_switch='semijoin=on,firstmatch=on,loosescan=on';
 set @@optimizer_switch='semijoin_with_cache=on';
 set @@optimizer_switch='outer_join_with_cache=on';

mysql-test/r/join_nested_jcl6.result

 set @save_optimizer_switch_jcl6=@@optimizer_switch;
+set @@optimizer_switch='optimize_join_buffer_size=on';
 set @@optimizer_switch='semijoin_with_cache=on';
 set @@optimizer_switch='outer_join_with_cache=on';
 set @@optimizer_switch='mrr=on,mrr_sort_keys=on,index_condition_pushdown=on';

mysql-test/r/join_outer_jcl6.result

 set @save_optimizer_switch_jcl6=@@optimizer_switch;
+set @@optimizer_switch='optimize_join_buffer_size=on';
 set @@optimizer_switch='semijoin_with_cache=on';
 set @@optimizer_switch='outer_join_with_cache=on';
 set optimizer_switch='mrr=on,mrr_sort_keys=on,index_condition_pushdown=on';

mysql-test/r/select_jcl6.result

 set @save_optimizer_switch_jcl6=@@optimizer_switch;
+set @@optimizer_switch='optimize_join_buffer_size=on';
 set @@optimizer_switch='semijoin_with_cache=on';
 set @@optimizer_switch='outer_join_with_cache=on';
 set @@optimizer_switch='mrr=on,mrr_sort_keys=on,index_condition_pushdown=on';

mysql-test/r/subselect3_jcl6.result

 set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch='optimize_join_buffer_size=on';
 set @@optimizer_switch='semijoin_with_cache=on';
 set @@optimizer_switch='outer_join_with_cache=on';
 set optimizer_switch='mrr=on,mrr_sort_keys=on,index_condition_pushdown=on';

mysql-test/r/subselect_sj2_jcl6.result

 set @save_optimizer_switch_jcl6=@@optimizer_switch;
+set @@optimizer_switch='optimize_join_buffer_size=on';
 set @@optimizer_switch='semijoin_with_cache=on';
 set @@optimizer_switch='outer_join_with_cache=on';
 set optimizer_switch='mrr=on,mrr_sort_keys=on,index_condition_pushdown=on';

mysql-test/r/subselect_sj_jcl6.result

 set @save_optimizer_switch_jcl6=@@optimizer_switch;
+set @@optimizer_switch='optimize_join_buffer_size=on';
 set @@optimizer_switch='semijoin=on,firstmatch=on,loosescan=on';
 set @@optimizer_switch='semijoin_with_cache=on';
 set @@optimizer_switch='outer_join_with_cache=on';

mysql-test/t/join_cache.test

@@ -4,6 +4,7 @@ DROP DATABASE IF EXISTS world;
 --enable_warnings
 
 set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch='optimize_join_buffer_size=on';
 set optimizer_switch='semijoin=on,firstmatch=on,loosescan=on';
 set @@optimizer_switch='semijoin_with_cache=on';
 set @@optimizer_switch='outer_join_with_cache=on';

mysql-test/t/join_nested_jcl6.test

@@ -3,6 +3,7 @@
 #
 
 set @save_optimizer_switch_jcl6=@@optimizer_switch;
+set @@optimizer_switch='optimize_join_buffer_size=on';
 set @@optimizer_switch='semijoin_with_cache=on';
 set @@optimizer_switch='outer_join_with_cache=on';
 set @@optimizer_switch='mrr=on,mrr_sort_keys=on,index_condition_pushdown=on';

mysql-test/t/join_outer_jcl6.test

@@ -3,6 +3,7 @@
 #
 
 set @save_optimizer_switch_jcl6=@@optimizer_switch;
+set @@optimizer_switch='optimize_join_buffer_size=on';
 set @@optimizer_switch='semijoin_with_cache=on';
 set @@optimizer_switch='outer_join_with_cache=on';
 set optimizer_switch='mrr=on,mrr_sort_keys=on,index_condition_pushdown=on';

mysql-test/t/select_jcl6.test

@@ -3,6 +3,7 @@
 #
 
 set @save_optimizer_switch_jcl6=@@optimizer_switch;
+set @@optimizer_switch='optimize_join_buffer_size=on';
 set @@optimizer_switch='semijoin_with_cache=on';
 set @@optimizer_switch='outer_join_with_cache=on';
 set @@optimizer_switch='mrr=on,mrr_sort_keys=on,index_condition_pushdown=on';

mysql-test/t/subselect3_jcl6.test

@@ -3,6 +3,7 @@
 #
 
 set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch='optimize_join_buffer_size=on';
 set @@optimizer_switch='semijoin_with_cache=on';
 set @@optimizer_switch='outer_join_with_cache=on';
 set optimizer_switch='mrr=on,mrr_sort_keys=on,index_condition_pushdown=on';

mysql-test/t/subselect_sj2_jcl6.test

@@ -3,6 +3,7 @@
 #
 
 set @save_optimizer_switch_jcl6=@@optimizer_switch;
+set @@optimizer_switch='optimize_join_buffer_size=on';
 set @@optimizer_switch='semijoin_with_cache=on';
 set @@optimizer_switch='outer_join_with_cache=on';
 set optimizer_switch='mrr=on,mrr_sort_keys=on,index_condition_pushdown=on';

mysql-test/t/subselect_sj_jcl6.test

@@ -3,6 +3,7 @@
 #
 
 set @save_optimizer_switch_jcl6=@@optimizer_switch;
+set @@optimizer_switch='optimize_join_buffer_size=on';
 set @@optimizer_switch='semijoin=on,firstmatch=on,loosescan=on';
 set @@optimizer_switch='semijoin_with_cache=on';
 set @@optimizer_switch='outer_join_with_cache=on';

sql/mysql_priv.h

@@ -613,8 +613,7 @@ enabled by default, add OPTIMIZER_SWITCH_MATERIALIZATION
                                     OPTIMIZER_SWITCH_SUBQUERY_CACHE|\
                                     OPTIMIZER_SWITCH_JOIN_CACHE_INCREMENTAL | \
                                     OPTIMIZER_SWITCH_JOIN_CACHE_HASHED | \
-                                    OPTIMIZER_SWITCH_JOIN_CACHE_BKA | \
-                                    OPTIMIZER_SWITCH_OPTIMIZE_JOIN_BUFFER_SIZE)
+                                    OPTIMIZER_SWITCH_JOIN_CACHE_BKA)
 
 /*
   Replication uses 8 bytes to store SQL_MODE in the binary log. The day you

sql/mysqld.cc

@@ -498,7 +498,7 @@ static const char *optimizer_switch_str="index_merge=on,index_merge_union=on,"
                                         "join_cache_incremental=on,"
                                         "join_cache_hashed=on,"
                                         "join_cache_bka=on,"
-                                        "optimize_join_buffer_size=on,"
+                                        "optimize_join_buffer_size=off,"
                                         "table_elimination=on";
                                         ;
 #ifdef SAFEMALLOC