Problem: when processing a query like:
SELECT '' LIKE '1' ESCAPE COUNT(1);
escape_item->val_str() was never executed and the "escape" class member
stayed initialized, which led to valgrind uninitialized memory error.
Note, a query with some tables in "FROM" clause
returns ER_WRONG_ARGUMENTS in the same situation:
SELECT '' LIKE '1' ESCAPE COUNT(1) FROM t1;
ERROR 1210 (HY000): Incorrect arguments to ESCAPE
Fix: disallowing using aggregate functions in ESCAPE clause,
even if there are no tables used. There is no much use of that anyway.
Problem: a flaw (derefencing a NULL pointer) in the LIKE optimization
code may lead to a server crash in some rare cases.
Fix: check the pointer before its dereferencing.
- Make the range-et-al optimizer produce E(#table records after table
condition is applied),
- Make the join optimizer use this value,
- Add "filtered" column to EXPLAIN EXTENDED to show
fraction of records left after table condition is applied
- Adjust test results, add comments
adding test case.
item_cmpfunc.cc:
Bug#12611
ESCAPE + LIKE do not work when the escape char is a multibyte one
Additional fix for 8bit character sets:
escape character must be converted into
operation character set.
