Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Duplicate
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10.1(EOL)
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10.1.8-3
Description
create table ten(a int);
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insert into ten values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
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create table twenty (a int, filler char(200), key(a));
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insert into twenty select A.a + B.a* 10, 'AAAAAAAAAAAAAAAAAAAA' from ten A, ten B where B.a in (0,1);
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explain format=json select distinct A.a from ten A, twenty B where A.a+B.a> 0;
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Crashes like this:
#0 0x00007ffff63b3425 in __GI_raise (sig=<optimized out>) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
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#1 0x00007ffff63b6b8b in __GI_abort () at abort.c:91
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#2 0x00007ffff63ac0ee in __assert_fail_base (fmt=<optimized out>, assertion=0x11010c0 "0", file=0x1101218 "/home/psergey/dev-git/10.1-explain-analyze-cp/sql/sql_explain.cc", line=<optimized out>, function=<optimized out>) at assert.c:94
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#3 0x00007ffff63ac192 in __GI___assert_fail (assertion=0x11010c0 "0", file=0x1101218 "/home/psergey/dev-git/10.1-explain-analyze-cp/sql/sql_explain.cc", line=1304, function=0x1101ca0 "void Explain_table_access::tag_to_json(Json_writer*, explain_extra_tag)") at assert.c:103
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#4 0x00000000007e31cf in Explain_table_access::tag_to_json (this=0x7fff940099f8, writer=0x7ffff016f010, tag=ET_DISTINCT) at /home/psergey/dev-git/10.1-explain-analyze-cp/sql/sql_explain.cc:1304
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#5 0x00000000007e3b20 in Explain_table_access::print_explain_json (this=0x7fff940099f8, query=0x7fff940091b0, writer=0x7ffff016f010, is_analyze=false, fs_tracker=0x0) at /home/psergey/dev-git/10.1-explain-analyze-cp/sql/sql_explain.cc:1491
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#6 0x00000000007e1e2f in Explain_basic_join::print_explain_json_interns (this=0x7fff94009320, query=0x7fff940091b0, writer=0x7ffff016f010, is_analyze=false, first_table_sort=0x0) at /home/psergey/dev-git/10.1-explain-analyze-cp/sql/sql_explain.cc:887
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#7 0x00000000007e1cb4 in Explain_select::print_explain_json (this=0x7fff94009320, query=0x7fff940091b0, writer=0x7ffff016f010, is_analyze=false) at /home/psergey/dev-git/10.1-explain-analyze-cp/sql/sql_explain.cc:850
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#8 0x00000000007dfd8e in Explain_query::print_explain_json (this=0x7fff940091b0, output=0x7fff94006850, is_analyze=false) at /home/psergey/dev-git/10.1-explain-analyze-cp/sql/sql_explain.cc:221
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#9 0x0000000000688a7a in execute_sqlcom_select (thd=0x306cb50, all_tables=0x7fff94005648) at /home/psergey/dev-git/10.1-explain-analyze-cp/sql/sql_parse.cc:5733
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#10 0x000000000067f102 in mysql_execute_command (thd=0x306cb50) at /home/psergey/dev-git/10.1-explain-analyze-cp/sql/sql_parse.cc:2926
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#11 0x000000000068c377 in mysql_parse (thd=0x306cb50, rawbuf=0x7fff940053c8 "explain format=json select distinct A.a from ten A, twenty B where A.a+B.a> 0", length=77, parser_state=0x7ffff01700c0) at /home/psergey/dev-git/10.1-explain-analyze-cp/sql/sql_parse.cc:7165
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Tabular EXPLAIN output:
+------+-------------+-------+-------+---------------+------+---------+------+------+------------------------------------------------------------------------+
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| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
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+------+-------------+-------+-------+---------------+------+---------+------+------+------------------------------------------------------------------------+
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| 1 | SIMPLE | A | ALL | NULL | NULL | NULL | NULL | 10 | Using temporary |
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| 1 | SIMPLE | B | index | NULL | a | 5 | NULL | 20 | Using where; Using index; Distinct; Using join buffer (flat, BNL join) |
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+------+-------------+-------+-------+---------------+------+---------+------+------+------------------------------------------------------------------------+
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This output is incorrect (this is an error from MySQL, see http://bugs.mysql.com/bug.php?id=76679)
But still, MariaDB should not crash.
Attachments
Activity
| Field | Original Value | New Value |
|---|---|---|
| Labels | explain_json |
| Workflow | MariaDB v2 [ 60505 ] | MariaDB v3 [ 67233 ] |
| Sprint | 10.1.8-3 [ 15 ] |
| Rank | Ranked lower |
The output is still wrong, though. Re-filed a copy of upstream bug #76679 as MDEV-8857.
| Fix Version/s | 10.1.8 [ 19605 ] | |
| Fix Version/s | 10.1 [ 16100 ] | |
| Resolution | Duplicate [ 3 ] | |
| Status | Open [ 1 ] | Closed [ 6 ] |
| Workflow | MariaDB v3 [ 67233 ] | MariaDB v4 [ 149047 ] |
For the record, MySQL' EXPLAIN FORMAT=JSON (note the "distinct": true):
MySQL [test]> explain format=json select distinct A.a from ten A, twenty B where A.a+B.a> 0\GF*************************** 1. row ***************************EXPLAIN: {"query_block": {"select_id": 1,"duplicates_removal": {"using_temporary_table": true,"using_filesort": false,"nested_loop": [{"table": {"table_name": "A","access_type": "ALL","rows": 10,"filtered": 100}},{"table": {"table_name": "B","access_type": "index","key": "a","used_key_parts": ["a"],"key_length": "5","rows": 20,"filtered": 100,"using_index": true,"distinct": true,"using_join_buffer": "Block Nested Loop","attached_condition": "((`test`.`A`.`a` + `test`.`B`.`a`) > 0)"}}]}}}