Query spends a long time in best_extension_by_limited_search with mrr enabled

--- a/sql/sql_priv.h         2014-07-10 23:01:30.000000000 -0700

+++ b/sql/sql_priv.h         2014-10-17 11:52:40.000000000 -0700

@@ -265,6 +265,8 @@ template <class T> bool valid_buffer_ran

                                     OPTIMIZER_SWITCH_EXTENDED_KEYS | \

                                     OPTIMIZER_SWITCH_IN_TO_EXISTS | \

                                     OPTIMIZER_SWITCH_MATERIALIZATION | \

+                                    OPTIMIZER_SWITCH_MRR | \

+                                    OPTIMIZER_SWITCH_MRR_SORT_KEYS | \

                                     OPTIMIZER_SWITCH_PARTIAL_MATCH_ROWID_MERGE|\

                                     OPTIMIZER_SWITCH_PARTIAL_MATCH_TABLE_SCAN|\

                                     OPTIMIZER_SWITCH_OUTER_JOIN_WITH_CACHE | \

--- a/sql/sys_vars.cc        2014-10-10 09:26:00.000000000 -0700

+++ b/sql/sys_vars.cc        2014-10-17 11:52:53.000000000 -0700

@@ -5488,7 +5488,7 @@ static Sys_var_ulong Sys_join_cache_leve

        "numbers are used for plain join buffers while even numbers are used "

        "for linked buffers",

        SESSION_VAR(join_cache_level), CMD_LINE(REQUIRED_ARG),

-       VALID_RANGE(0, 8), DEFAULT(2), BLOCK_SIZE(1));

+       VALID_RANGE(0, 8), DEFAULT(8), BLOCK_SIZE(1));

 static Sys_var_ulong Sys_mrr_buffer_size(

        "mrr_buffer_size",

#1  0x0000000002bf4175 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=14876672, idx=23, record_count=11920928955078124, read_time=3323366612638157.5, search_depth=39, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7630

#2  0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=15400960, idx=22, record_count=2384185791015625, read_time=661748557793711.75, search_depth=40, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#3  0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=15663104, idx=21, record_count=476837158203125, read_time=131625014508403, search_depth=41, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#4  0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=149880832, idx=20, record_count=95367431640625, read_time=26211850088810.25, search_depth=42, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#5  0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=183435264, idx=19, record_count=19073486328125, read_time=5218711483537.75, search_depth=43, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#6  0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=200212480, idx=18, record_count=3814697265625, read_time=1037684303952.5, search_depth=44, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#7  0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=201261056, idx=17, record_count=762939453125, read_time=206371221932.25, search_depth=45, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#8  0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268369920, idx=16, record_count=152587890625, read_time=41087076301, search_depth=46, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#9  0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268402688, idx=15, record_count=30517578125, read_time=8171051506.75, search_depth=47, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#10 0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268419072, idx=14, record_count=6103515625, read_time=1626985377.5, search_depth=48, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#11 0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268427264, idx=13, record_count=1220703125, read_time=323899784, search_depth=49, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#12 0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268431360, idx=12, record_count=244140625, read_time=64409097.25, search_depth=50, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#13 0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268433408, idx=11, record_count=48828125, read_time=12824070.75, search_depth=51, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#14 0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268434432, idx=10, record_count=9765625, read_time=2552885, search_depth=52, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#15 0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268434944, idx=9, record_count=1953125, read_time=507653.5, search_depth=53, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#16 0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268435200, idx=8, record_count=390625, read_time=101110.25, search_depth=54, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#17 0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268435328, idx=7, record_count=78125, read_time=20166.5, search_depth=55, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#18 0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268435392, idx=6, record_count=15625, read_time=4049.5, search_depth=56, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#19 0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268435424, idx=5, record_count=3125, read_time=842.5, search_depth=57, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#20 0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268435440, idx=4, record_count=625, read_time=197, search_depth=58, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#21 0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268435448, idx=3, record_count=125, read_time=61.75, search_depth=59, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#22 0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268435452, idx=2, record_count=25, read_time=26.5, search_depth=60, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#23 0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268435454, idx=1, record_count=5, read_time=11.25, search_depth=61, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#24 0x0000000002bf4846 in best_extension_by_limited_search (join=0x7fffe7d52c70, remaining_tables=268435455, idx=0, record_count=1, read_time=0, search_depth=62, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:7750

#25 0x0000000002bd31a8 in greedy_search (join=0x7fffe7d52c70, remaining_tables=268435455, search_depth=62, prune_level=1, use_cond_selectivity=1) at sql/sql_select.cc:6926

#26 0x0000000002bd1c27 in choose_plan (join=0x7fffe7d52c70, join_tables=268435455) at sql/sql_select.cc:6503

#27 0x0000000002bba03c in make_join_statistics (join=0x7fffe7d52c70, tables_list=..., conds=0x7fffe8154a08, keyuse_array=0x7fffe7d52f78) at sql/sql_select.cc:4047

#28 0x0000000002bb461b in JOIN::optimize_inner (this=0x7fffe7d52c70) at sql/sql_select.cc:1367

#29 0x0000000002bb3504 in JOIN::optimize (this=0x7fffe7d52c70) at sql/sql_select.cc:1052

#30 0x0000000002bb09ec in mysql_select (thd=0x7ffff3a14090, rref_pointer_array=0x7ffff3a18318, tables=0x7fffefb6ee10, wild_num=0, fields=..., conds=0x0, og_num=0, order=0x0, group=0x0, having=0x0, proc_param=0x0, select_options=2147748612, result=0x7fffe7d525b0, unit=0x7ffff3a17968, select_lex=0x7ffff3a180a0) at sql/sql_select.cc:3318

#31 0x0000000002be4ec7 in mysql_explain_union (thd=0x7ffff3a14090, unit=0x7ffff3a17968, result=0x7fffe7d525b0) at sql/sql_select.cc:23897

#32 0x0000000002b69913 in execute_sqlcom_select (thd=0x7ffff3a14090, all_tables=0x7fffefb6ee10) at sql/sql_parse.cc:5442

#33 0x0000000002b60464 in mysql_execute_command (thd=0x7ffff3a14090) at sql/sql_parse.cc:2660

#34 0x0000000002b5e1ef in mysql_parse (thd=0x7ffff3a14090, rawbuf=0x7fffefb6e8a8 "EXPLAIN SELECT CAST(f1 AS SIGNED INTEGER) AS f1,\nCAST(f2 AS CHAR) AS f2 FROM test1.v27", length=86, parser_state=0x7ffff6e64158) at sql/sql_parse.cc:6696

#35 0x0000000002b5b373 in dispatch_command (command=COM_QUERY, thd=0x7ffff3a14090, packet=0x7ffff2f61091 "", packet_length=86) at sql/sql_parse.cc:1349

#36 0x0000000002b5d93a in do_command (thd=0x7ffff3a14090) at sql/sql_parse.cc:1034

#37 0x0000000002b1391e in do_handle_one_connection (thd_arg=0x7ffff3a14090) at sql/sql_connect.cc:1397

#38 0x0000000002b136e2 in handle_one_connection (arg=0x7ffff3a14090) at sql/sql_connect.cc:1311

#39 0x00007ffff728214e in start_thread () from /usr/grte/v3/lib64/libpthread.so.0

#40 0x00007ffff6ef869d in clone () from /usr/grte/v3/lib64/libc.so.6

#41 0x0000000000000000 in ?? ()