Current table is placed into read_tables set of the current join_tab->select
so get_mm_parts function thinks that current table's record is read and
tries to calculate WHERE condition with the fields of the record.
Result of these calculations is unpredictable.
Looks funny - outcome of the SELECT depends on the queries executed before.
Anyway i think we should have testcase on this part of the code.
It looks like samll revolution in SELECT_LEX tree, but it was only natural way to solve problem with name resolution of external fields inside subselect which belongs to global order of union
also it have following advantages:
- removed mess with current_select type conversion
- type checking/converting
- a lot of virtual methods
- fake select for union execution allocated only once (it was allocated for every subselect with union executing)
changes:
fixed bug with outer fields name resolution of subqueries which belong to global ORDER BY clause
remuved select_lex() function, now thd->lex.current_select always have type SELECT_LEX
new SELECT_LEX (fake_select_lex) will be allocated in case of UNION for using in UNION processing
fake_select_lex allocated for union hold global ORDER BY & LIMIT clauses and have linkage equal to GLOBAL_OPTIONS_TYPE
new description of SELECT_LEX tree
(SCRUM)
Query should actually return empty result set, but currently can't, as
it attempts to store NULL in NOT NULL field, because that is a match
made by self join conditions.
This crash happens in rather exotic case when we try to run
SELECT DISTINCT some_func(SUM(some_field)) GROUP BY another_field;
on a table with single row.
Optimizer marks this table as const, sets group=NULL (with remove_const)
thus, create_tmp_table makes mistake collecting columns for temporary table
and then crashes because the field_count gets less than hidden_columns_count.
bmove_allign -> bmove_align
Added OLAP function ROLLUP
Split mysql_fix_privilege_tables to a script and a .sql data file
Added new (MEMROOT*) functions to avoid calling current_thd() when creating some common objects.
Added table_alias_charset, for easier --lower-case-table-name handling
Better SQL_MODE handling (Setting complex options also sets sub options)
New (faster) assembler string functions for x86
