The problem has manifested itself in the cases when we have a nested outer join
for which it can be inferred that one of the inner tables is a single row table.
* Provide backwards compatibility extension to name resolution of
coalesced columns. The patch allows such columns to be qualified
with a table (and db) name, as it is in 4.1.
Based on a patch from Monty.
* Adjusted tests accordingly to test both backwards compatible name
resolution of qualified columns, and ANSI-style resolution of
non-qualified columns.
For this, each affected test has two versions - one with qualified
columns, and one without.
"Process NATURAL and USING joins according to SQL:2003".
* Some of the main problems fixed by the patch:
- in "select *" queries the * expanded correctly according to
ANSI for arbitrary natural/using joins
- natural/using joins are correctly transformed into JOIN ... ON
for any number/nesting of the joins.
- column references are correctly resolved against natural joins
of any nesting and combined with arbitrary other joins.
* This patch also contains a fix for name resolution of items
inside the ON condition of JOIN ... ON - in this case items must
be resolved only against the JOIN operands. To support such
'local' name resolution, the patch introduces a stack of
name resolution contexts used at parse time.
NOTICE:
- This patch is not complete in the sense that
- there are 2 test cases that still do not pass -
one in join.test, one in select.test. Both are marked
with a comment "TODO: WL#2486".
- it does not include a new test specific for the task
Fixed bug #12154: a query returned: Column <name> cannot be null.
The problem was due to a bug in the function setup_table_map:
the flag maybe_null was set up incorrectly for inner tables of
nested outer joins.
join_nested.result, join_nested.test:
Added a test case for bug #12154.
Added a teast case for bug #11284.
sql_select.cc:
Fixed bug #11284.
Optimization with empty inner table currently cannot be
used in the case of nested outer join.
Added a case for bug #4976 when one of the inner tables is empty.
select.result, join.result:
Reversed the previous change of the erronious fix for bug #4976.
sql_select.cc:
The previous fix for bug 4976 was reversed as it
erroniously converted an outer join into an innner join
when on_expression does not refer to outer tables.
This is not valid if inner tables return an empty set.
Setting dependency on outer tables was added for the above cases.
To fix the crash in the test case of bug #4976
a guard was added that blocks running the crashing code for
nested outer joins.
Fixed bug #4976.
join_nested.result, join_nested.test:
Added a test case for bug #4976.
sql_select.cc:
Applied conversion from an outer join to an inner join
when the on expression does not depend on the outer table.
It fixed bug #4976.
Added a test case for bug #4922.
sql_select.cc:
Blocked an optimization performed by join_read_const_table when
applied to an inner table of a nested outer join.
It was done to fix bug #4922.
sql_yacc.yy:
Fixed a typo bug in the rule for join_table.
