SHOW EXPLAIN: server crashes in JOIN::print_explain on a query with impossible WHERE

#3  <signal handler called>

#4  0x00000000007a86e2 in JOIN::print_explain (this=0x1d404b8, result=0x1cb3ab8, 

    explain_flags=0 '\000', on_the_fly=true, need_tmp_table=false, need_order=false, 

    distinct=false, message=0x0) at sql_select.cc:21264

#5  0x00000000005d611d in st_select_lex::print_explain (this=0x1cf1100, 

    output=0x1cb3ab8, explain_flags=0 '\000') at sql_lex.cc:3769

#6  0x00000000005d628f in st_select_lex_unit::print_explain (this=0x1cf1450, 

    output=0x1cb3ab8, explain_flags=0 '\000') at sql_lex.cc:3820

#7  0x00000000005d6189 in st_select_lex::print_explain (this=0x1ce2098, 

    output=0x1cb3ab8, explain_flags=0 '\000') at sql_lex.cc:3784

#8  0x00000000005d628f in st_select_lex_unit::print_explain (this=0x1ce1b90, 

    output=0x1cb3ab8, explain_flags=0 '\000') at sql_lex.cc:3820

#9  0x00000000006ccbc5 in Show_explain_request::get_explain_data (arg=0x7f5ae1c5bba0)

    at sql_class.cc:3042

#10 0x000000000095b335 in Apc_target::process_apc_requests (this=0x1ce1900)

    at my_apc.cc:255

#11 0x00000000006c8a30 in THD::check_killed (this=0x1cdf5e8) at sql_class.cc:1904

#12 0x0000000000744c9f in JOIN_CACHE::join_matching_records (this=0x1d4d658, 

    skip_last=false) at sql_join_cache.cc:2238

#13 0x00000000007447fa in JOIN_CACHE::join_records (this=0x1d4d658, skip_last=false)

    at sql_join_cache.cc:2064

#14 0x0000000000799de5 in sub_select_cache (join=0x1d3fe78, join_tab=0x1d4d158, 

    end_of_records=true) at sql_select.cc:15532

#15 0x000000000079a004 in sub_select (join=0x1d3fe78, join_tab=0x1d4ce38, 

    end_of_records=true) at sql_select.cc:15694

#16 0x0000000000799ab5 in do_select (join=0x1d3fe78, fields=0x1ce21a0, table=0x0, 

    procedure=0x0) at sql_select.cc:15416

#17 0x000000000077aa4e in JOIN::exec_inner (this=0x1d3fe78) at sql_select.cc:2810

#18 0x0000000000777e31 in JOIN::exec (this=0x1d3fe78) at sql_select.cc:2125

#19 0x000000000077b2e7 in mysql_select (thd=0x1cdf5e8, rref_pointer_array=0x1ce22f0, 

    tables=0x1cf07a0, wild_num=0, fields=..., conds=0x1d3fcc8, og_num=0, order=0x0, 

    group=0x0, having=0x0, proc_param=0x0, select_options=2147764736, result=0x1d3fe58, 

    unit=0x1ce1b90, select_lex=0x1ce2098) at sql_select.cc:3031

#20 0x0000000000771d62 in handle_select (thd=0x1cdf5e8, lex=0x1ce1af0, result=0x1d3fe58, 

    setup_tables_done_option=0) at sql_select.cc:332

#21 0x00000000007002d9 in execute_sqlcom_select (thd=0x1cdf5e8, all_tables=0x1cf07a0)

    at sql_parse.cc:5178

#22 0x00000000006f721f in mysql_execute_command (thd=0x1cdf5e8) at sql_parse.cc:2285

#23 0x0000000000702cb4 in mysql_parse (thd=0x1cdf5e8, 

    rawbuf=0x1cf0520 "SELECT a1 FROM A, B \nWHERE a1 < ALL ( \nSELECT a1 FROM A \nWHERE a1 IN ( SELECT a1 FROM A, C ) \n)", length=95, found_semicolon=0x7f5ae1c14c98)

    at sql_parse.cc:6179

#24 0x00000000006f49ce in dispatch_command (command=COM_QUERY, thd=0x1cdf5e8, 

    packet=0x1ce9bb9 "", packet_length=95) at sql_parse.cc:1229

#25 0x00000000006f3d02 in do_command (thd=0x1cdf5e8) at sql_parse.cc:924

#26 0x00000000006f0b46 in handle_one_connection (arg=0x1cdf5e8) at sql_connect.cc:1218

index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on

id      select_type     table   type    possible_keys   key     key_len ref     rows    filtered  Extra

1       PRIMARY A       index   NULL    a1      5       NULL    20      100.00  Using where; Using index

1       PRIMARY B       ALL     NULL    NULL    NULL    NULL    87      100.00  Using join buffer (flat, BNL join)

2       SUBQUERY        NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL    Impossible WHERE noticed after reading const tables

Warnings:

Note    1003    select `test`.`A`.`a1` AS `a1` from `test`.`A` join `test`.`B` where <not>(<in_optimizer>(`test`.`A`.`a1`,(<min>(select `test`.`A`.`a1` from `test`.`A` semi join (`test`.`A` join `test`.`C`) where 0) <= <cache>(`test`.`A`.`a1`))))

revision-id: psergey@askmonty.org-20120515115650-kqeip9cgxltgzx75

date: 2012-05-15 15:56:50 +0400

revno: 3511

CREATE TABLE A (a1 INT, KEY(a1)) ENGINE=MyISAM;

INSERT INTO A VALUES

  (4),(6),(7),(1),(0),(7),(7),(1),(7),(1),

  (5),(2),(0),(1),(8),(1),(1),(9),(1),(5);

CREATE TABLE B (b1 INT) ENGINE=MyISAM;

INSERT INTO B VALUES

  (4),(5),(8),(4),(8),(2),(9),(6),(4),(8),

  (3),(5),(9),(6),(8),(3),(2),(6),(3),(1),

  (4),(3),(1),(7),(0),(0),(9),(5),(9),(0),

  (2),(2),(5),(9),(1),(4),(8),(6),(5),(5),

  (1),(7),(2),(8),(9),(3),(2),(6),(6),(5),

  (4),(3),(2),(7),(4),(6),(0),(8),(5),(8),

  (2),(9),(7),(5),(7),(0),(4),(3),(1),(0),

  (6),(2),(8),(3),(7),(3),(5),(5),(1),(2),

  (1),(7),(1),(9),(9),(8),(3);

CREATE TABLE C (c1 INT) ENGINE=MyISAM;

--connect (con1,localhost,root,,)

--let $con_id = `SELECT CONNECTION_ID()`

--send

SELECT a1 FROM A, B

WHERE a1 < ALL ( 

  SELECT a1 FROM A

  WHERE a1 IN ( SELECT a1 FROM A, C )

);

--connection default

--let $run = 100

while ($run)

{

  --error 0,1220

  --eval SHOW EXPLAIN FOR $con_id

  --dec $run

}

--connection con1

--reap

DROP TABLE A, B, C;