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cf79c01cc7
Analysis:
The crash is a result of incorrect analysis of whether a secondary key
can be extended with a primary in order to compute ORDER BY. The analysis
is done in test_if_order_by_key(). This function doesn't take into account
that the primary key may in fact index the same columns as the secondary
key. For the test query test_if_order_by_key says that there is an extended
key with total 2 keyparts.
At the same time, the condition
if (pkinfo->key_part[i].field->key_start.is_set(nr))
in test_if_cheaper_oredring() becomes true for (i == 0), which results in
an invalid access to rec_per_key[-1].
Solution:
The best solution would be to reuse KEY::ext_key_parts that is already computed
by open_binary_frm(), however after detailed analysis the conclusion is that
the change would be too intrusive for a GA release.
The solution for 5.5 is to add a guard for the case when the 0-th key part is
considered, and to assume that all keys will be scanned in this case.
30 lines
970 B
Text
30 lines
970 B
Text
#
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# MDEV-3992 Server crash or valgrind errors in test_if_skip_sort_order/test_if_cheaper_ordering
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# on GROUP BY with indexes on InnoDB table
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#
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CREATE TABLE t1 (
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pk INT PRIMARY KEY,
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a VARCHAR(1) NOT NULL,
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KEY (pk)
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) ENGINE=InnoDB;
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INSERT INTO t1 VALUES (1,'a'),(2,'b');
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EXPLAIN
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SELECT COUNT(*), pk field1, pk AS field2
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FROM t1 WHERE a = 'r' OR pk = 183
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GROUP BY field1, field2;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 index PRIMARY,pk pk 4 NULL 2 Using where
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SELECT COUNT(*), pk field1, pk AS field2
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FROM t1 WHERE a = 'r' OR pk = 183
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GROUP BY field1, field2;
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COUNT(*) field1 field2
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EXPLAIN
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SELECT COUNT(*), pk field1 FROM t1
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WHERE a = 'r' OR pk = 183 GROUP BY field1, field1;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 index PRIMARY,pk pk 4 NULL 2 Using where
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SELECT COUNT(*), pk field1 FROM t1
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WHERE a = 'r' OR pk = 183 GROUP BY field1, field1;
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COUNT(*) field1
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drop table t1;
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End of 5.5 tests
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