| Bug #117995 | Contribution by Tencent: explain analyze format=json causes crash | ||
|---|---|---|---|
| Submitted: | 16 Apr 9:01 | Modified: | 19 May 23:45 |
| Reporter: | Peiyuan Liu (OCA) | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Server: Optimizer | Severity: | S6 (Debug Builds) |
| Version: | trunk, 9.3.0, 8.4.5 | OS: | Any |
| Assigned to: | CPU Architecture: | Any | |
| Tags: | Contribution | ||
[16 Apr 9:01]
Peiyuan Liu
[16 Apr 9:19]
MySQL Verification Team
Hello Peiyuan Liu, Thank you for the report and test case. Verified as described. regards, Umesh
[16 Apr 9:20]
MySQL Verification Team
-- 9.3.0 debug build [umshastr@bug117958:/bv/mybugs/mysql-9.3.0/mysql-test]$ ./mtr --nocheck-testcases bug117995 --debug-server Logging: ./mtr --nocheck-testcases bug117995 --debug-server MySQL Version 9.3.0 Checking supported features - Binaries are debug compiled Using 'all' suites Collecting tests Checking leftover processes Removing old var directory Creating var directory '/bv/mybugs/mysql-9.3.0/mysql-test/var' Installing system database Using parallel: 1 ports_per_thread:30 ============================================================================== TEST NAME RESULT TIME (ms) COMMENT ------------------------------------------------------------------------------ use test; set explain_json_format_version = 1; explain analyze format=json select * from ( select 1) b; [ 50%] main.bug117995 [ fail ] Test ended at 2025-04-16 11:18:52 CURRENT_TEST: main.bug117995 mysqltest: At line 3: Query failed. Query: 'explain analyze format=json select * from ( select 1) b' Returned error: 2013 (HY000): Lost connection to MySQL server during query -bt #0 0x00007f9635e7356c in __pthread_kill_implementation () from /lib64/libc.so.6 #1 0x00000000042eb4e5 in my_write_core (sig=sig@entry=6) at ../../mysql-9.3.0/mysys/stacktrace.cc:342 #2 0x00000000035123bc in handle_fatal_signal (sig=6, info=0x7f962420a5b0, ucontext=0x7f962420a480) at ../../mysql-9.3.0/sql/signal_handler.cc:411 #3 <signal handler called> #4 0x00007f9635e7356c in __pthread_kill_implementation () from /lib64/libc.so.6 #5 0x00007f9635e26686 in raise () from /lib64/libc.so.6 #6 0x00007f9635e10833 in abort () from /lib64/libc.so.6 #7 0x00007f9635e1075b in __assert_fail_base.cold () from /lib64/libc.so.6 #8 0x00007f9635e1f3c6 in __assert_fail () from /lib64/libc.so.6 #9 0x00000000037f7c2d in explain_query_specification (explain_thd=explain_thd@entry=0x7f9568001040, query_thd=query_thd@entry=0x7f9568001040, query_term=<optimized out>, ctx=ctx@entry=CTX_JOIN) at ../../mysql-9.3.0/sql/opt_explain.cc:2100 #10 0x00000000037f7cef in mysql_explain_query_expression (explain_thd=0x7f9568001040, query_thd=0x7f9568001040, unit=unit@entry=0x7f956800d9c0) at ../../mysql-9.3.0/sql/opt_explain.cc:2392 #11 0x00000000037f7466 in (anonymous namespace)::Explain::explain_subqueries (this=this@entry=0x7f962420afe0) at ../../mysql-9.3.0/sql/opt_explain.cc:692 #12 0x00000000037f771c in (anonymous namespace)::Explain::send (this=this@entry=0x7f962420afe0) at ../../mysql-9.3.0/sql/opt_explain.cc:770 #13 0x00000000037f7b9c in explain_query_specification (explain_thd=explain_thd@entry=0x7f9568001040, query_thd=query_thd@entry=0x7f9568001040, query_term=0x7f956800bce0, ctx=ctx@entry=CTX_JOIN) at ../../mysql-9.3.0/sql/opt_explain.cc:2088 #14 0x00000000037f7cef in mysql_explain_query_expression (explain_thd=explain_thd@entry=0x7f9568001040, query_thd=query_thd@entry=0x7f9568001040, unit=unit@entry=0x7f956800bc20) at ../../mysql-9.3.0/sql/opt_explain.cc:2392 #15 0x00000000037fb436 in explain_query (explain_thd=explain_thd@entry=0x7f9568001040, query_thd=query_thd@entry=0x7f9568001040, unit=unit@entry=0x7f956800bc20) at ../../mysql-9.3.0/sql/opt_explain.cc:2356 #16 0x00000000033d911c in Sql_cmd_dml::execute_inner (this=<optimized out>, thd=0x7f9568001040) at ../../mysql-9.3.0/sql/sql_select.cc:1140 #17 0x00000000033d982b in Sql_cmd_dml::execute (this=0x7f9568020220, thd=0x7f9568001040) at ../../mysql-9.3.0/sql/sql_select.cc:791 #18 0x00000000033766a3 in mysql_execute_command (thd=thd@entry=0x7f9568001040, first_level=first_level@entry=true) at ../../mysql-9.3.0/sql/sql_parse.cc:4757 #19 0x0000000003377cad in dispatch_sql_command (thd=0x7f9568001040, parser_state=parser_state@entry=0x7f962420cb10, is_retry=is_retry@entry=false) at ../../mysql-9.3.0/sql/sql_parse.cc:5431 #20 0x00000000033792df in dispatch_command (thd=<optimized out>, thd@entry=0x7f9568001040, com_data=com_data@entry=0x7f962420d9e0, command=COM_QUERY) at ../../mysql-9.3.0/sql/sql_parse.cc:2147 #21 0x000000000337aa8c in do_command (thd=thd@entry=0x7f9568001040) at ../../mysql-9.3.0/sql/sql_parse.cc:1490 #22 0x00000000035023ac in handle_connection (arg=arg@entry=0xbee15c0) at ../../mysql-9.3.0/sql/conn_handler/connection_handler_per_thread.cc:304 #23 0x0000000004b1eb9e in pfs_spawn_thread (arg=0xc0b1600) at ../../../mysql-9.3.0/storage/perfschema/pfs.cc:3067 #24 0x00007f9635e717f2 in start_thread () from /lib64/libc.so.6 #25 0x00007f9635ef6880 in clone3 () from /lib64/libc.so.6
[16 Apr 9:23]
MySQL Verification Team
-- 8.4.5 debug build affected as well [umshastr@bug117958:/bv/mybugs/mysql-8.4.5/mysql-test]$ ./mtr --nocheck-testcases bug117995 --debug-server Logging: ./mtr --nocheck-testcases bug117995 --debug-server MySQL Version 8.4.5 Checking supported features - Binaries are debug compiled Using 'all' suites Collecting tests Removing old var directory Creating var directory '/bv/mybugs/mysql-8.4.5/mysql-test/var' Installing system database Using parallel: 1 ============================================================================== TEST NAME RESULT TIME (ms) COMMENT ------------------------------------------------------------------------------ use test; set explain_json_format_version = 1; explain analyze format=json select * from ( select 1) b; [ 50%] main.bug117995 [ fail ] Test ended at 2025-04-16 11:22:11 CURRENT_TEST: main.bug117995 mysqltest: At line 3: Query 'explain analyze format=json select * from ( select 1) b' failed. ERROR 2013 (HY000): Lost connection to MySQL server during query
[16 Apr 13:25]
Peiyuan Liu
suggested fix: return immediately after calling my_error in `if (lex->is_explain_analyze)` branch.
```
diff --git a/sql/opt_explain.cc b/sql/opt_explain.cc
index 37106df21a2..e0fb6fda413 100644
--- a/sql/opt_explain.cc
+++ b/sql/opt_explain.cc
@@ -2294,6 +2294,7 @@ bool explain_query(THD *explain_thd, const THD *query_thd,
my_error(ER_NOT_SUPPORTED_YET, MYF(0),
"EXPLAIN ANALYZE with TRADITIONAL format");
}
+ return true;
}
// Non-iterator-based formats are not supported with the hypergraph
```
[17 Apr 8:07]
MySQL Verification Team
Hello Peiyuan Liu, I'll follow up with the community team and let you know if anything further needed. Thank you. regards, Umesh
[25 Apr 7:49]
Peiyuan Liu
bugfix: explain analyze format=jsonv1 causes crash (*) I confirm the code being submitted is offered under the terms of the OCA, and that I am authorized to contribute it.
Contribution: 0001-bugfix-explain-analyze-format-jsonv1-crash.patch (application/octet-stream, text), 716 bytes.
[25 Apr 8:09]
MySQL Verification Team
Thank you, for your Contribution. regards, Umesh
[19 May 23:45]
Jon Stephens
Documented fix as follows in the MySQL 9.4.0 changelog:
EXPLAIN ANALYZE FORMAT=JSON did not handle queries with
subqueries correctly when explain_json_format_version was equal
to 1.
Our thanks to Peiyuan Liu and the Tencent team for the
contribution.
Closed.
