Details
Major
Description
#2 0x0000000000864189 in handle_fatal_signal (sig=11) at 10.0/sql/signal_handler.cc:262 #3 <signal handler called> #4 0x00000000007c4f24 in Explain_union::print_explain (this=0x7fee28b77b68, query=0x7fee28b77aa8, output=0x7fee325b4d10, explain_flags=0 '\000') at 10.0/sql/sql_explain.cc:228 #5 0x00000000007c53cc in Explain_node::print_explain_for_children (this=0x7fee28b78ff0, query=0x7fee28b77aa8, output=0x7fee325b4d10, explain_flags=0 '\000') at 10.0/sql/sql_explain.cc:327 #6 0x00000000007c57a7 in Explain_select::print_explain (this=0x7fee28b78ff0, query=0x7fee28b77aa8, output=0x7fee325b4d10, explain_flags=0 '\000') at 10.0/sql/sql_explain.cc:390 #7 0x00000000007c4c9c in Explain_query::print_explain (this=0x7fee28b77aa8, output=0x7fee325b4d10, explain_flags=0 '\000') at 10.0/sql/sql_explain.cc:175 #8 0x00000000007c4d63 in Explain_query::print_explain_str (this=0x7fee28b77aa8, thd=0x7fee2b32f070, out_str=0x7fee325b4e70) at 10.0/sql/sql_explain.cc:197 #9 0x00000000007c4cd0 in print_explain_query (lex=0x7fee2b332cc0, thd=0x7fee2b32f070, str=0x7fee325b4e70) at 10.0/sql/sql_explain.cc:182 #10 0x000000000093552b in MYSQL_QUERY_LOG::write (this=0x7fee2c3d6150, thd=0x7fee2b32f070, current_time=1405123297, user_host=0x7fee325b52a0 "root[root] @ localhost []", user_host_len=25, query_utime=1563, lock_utime=733, is_command=false, sql_text=0x7fee28819088 "SELECT * FROM t1 WHERE a >= ANY ( SELECT 'foo' UNION SELECT 'bar' )", sql_text_len=67) at 10.0/sql/log.cc:2926 #11 0x000000000093088b in Log_to_file_event_handler::log_slow (this=0x7fee2c3d5c00, thd=0x7fee2b32f070, current_time=..., user_host=0x7fee325b52a0 "root[root] @ localhost []", user_host_len=25, query_utime=1563, lock_utime=733, is_command=false, sql_text=0x7fee28819088 "SELECT * FROM t1 WHERE a >= ANY ( SELECT 'foo' UNION SELECT 'bar' )", sql_text_len=67) at 10.0/sql/log.cc:1018 #12 0x000000000093129e in LOGGER::slow_log_print (this=0x18a1600, thd=0x7fee2b32f070, query=0x7fee28819088 "SELECT * FROM t1 WHERE a >= ANY ( SELECT 'foo' UNION SELECT 'bar' )", query_length=67, current_utime=52081142100) at 10.0/sql/log.cc:1309 #13 0x000000000093d254 in slow_log_print (thd=0x7fee2b32f070, query=0x7fee28819088 "SELECT * FROM t1 WHERE a >= ANY ( SELECT 'foo' UNION SELECT 'bar' )", query_length=67, current_utime=52081142100) at 10.0/sql/log.cc:6020 #14 0x000000000067708c in log_slow_statement (thd=0x7fee2b32f070) at 10.0/sql/sql_parse.cc:1823 #15 0x0000000000676d62 in dispatch_command (command=COM_QUERY, thd=0x7fee2b32f070, packet=0x7fee2c3f6071 "", packet_length=67) at 10.0/sql/sql_parse.cc:1743 #16 0x0000000000674be2 in do_command (thd=0x7fee2b32f070) at 10.0/sql/sql_parse.cc:1006 #17 0x0000000000790ab5 in do_handle_one_connection (thd_arg=0x7fee2b32f070) at 10.0/sql/sql_connect.cc:1379 #18 0x0000000000790808 in handle_one_connection (arg=0x7fee2b32f070) at 10.0/sql/sql_connect.cc:1293 #19 0x0000000000cc22f6 in pfs_spawn_thread (arg=0x7fee2a6a0970) at 10.0/storage/perfschema/pfs.cc:1860 #20 0x00007fee321a0b50 in start_thread (arg=<optimized out>) at pthread_create.c:304 #21 0x00007fee30698a7d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
Stack trace from:
revision-id: knielsen@knielsen-hq.org-20140711100647-nf3rdaf5ep26pgty revno: 4290 branch-nick: 10.0
Test case:
SET NAMES tis620; SET GLOBAL slow_query_log = 1; SET long_query_time = 0.000001; SET log_slow_verbosity = 'explain'; CREATE TABLE t1 (a VARCHAR(3)) ENGINE=MyISAM; SELECT * FROM t1 WHERE a >= ANY ( SELECT 'foo' UNION SELECT 'bar' );
Gliffy Diagrams
Attachments
Activity
- All
- Comments
- Work Log
- History
- Activity
- Transitions
The inner JOIN::optimize() call doesn't save the query plan. this branch
if (was_optimized != optimized && !res && have_query_plan != QEP_DELETED)
is not taken, because was_optimized != optimized.
Then, the UNION is executed. It calls JOIN::exec() which calls JOIN::join_free()
which computes
bool full= !(select_lex->uncacheable) && !(thd->lex->describe);
to be true, calls JOIN::cleanup(full=true) which deletes the query plan and
sets have_query_plan= QEP_DELETED. This will prevent the outer-most
JOIN::optimize from saving the query plan (it will be already deleted).
When we arrive at the phase where EXPLAIN should be printed, we will crash
because one part of UNION will not have the query plan.
Why not change the condition in JOIN::optimize() to be
1. We have the query plan ( we might not have it if optimization failed with an error), AND
2. "explain data structure has no query plan for this select yet".
This should cover all cases.. or it seems so at first glance.
Debugging, I can see this:
JOIN::optimize() is called for " select 'foo'" (select_number=2). Then, it calls Item_allany_subselect::transform_into_max_min, which calls agg_item_set_converter... which eventually sees the item as inexpensive and calls Item_singlerow_subselect::val_str, which tries to execute the UNION. That is, JOIN::optimize() indirectly calls itself for the same object.