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MWL#17: Table elimination

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- Fix print_join() to work both for EXPLAIN EXTENDED (after table elimination) and for 
  CREATE VIEW (after join->prepare() but without any optimization).

mysql-test/r/union.result:
  MWL#17: Table elimination
  - Adjust test results
This commit is contained in:
Sergey Petrunia
2009-06-15 00:59:24 +04:00
parent b1e25edc9b
commit 6b4727dcb9
2 changed files with 17 additions and 7 deletions
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22
sql/sql_select.cc
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@@ -16937,18 +16937,28 @@ static void print_join(THD *thd,
*t= ti++;
DBUG_ASSERT(tables->elements >= 1);
//pserey:TODO check!
/*
Assert that the first table in the list isn't eliminated (if it was we
would have skipped the entire join nest)
*/
DBUG_ASSERT(!eliminated_tables ||
!((*table)->table && ((*table)->table->map & eliminated_tables) ||
(*table)->nested_join && !((*table)->nested_join->used_tables &
~eliminated_tables)));
(*table)->print(thd, eliminated_tables, str, query_type);
TABLE_LIST **end= table + tables->elements;
for (TABLE_LIST **tbl= table + 1; tbl < end; tbl++)
{
TABLE_LIST *curr= *tbl;
// psergey-todo-todo:
// base table: check
if (curr->table && (curr->table->map & eliminated_tables) ||
curr->nested_join && !(curr->nested_join->used_tables &
~eliminated_tables))
/*
The (*) check guards againist the case of printing the query for
CREATE VIEW. There we'll have nested_join->used_tables==0.
*/
if (eliminated_tables && // (*)
(curr->table && (curr->table->map & eliminated_tables) ||
curr->nested_join && !(curr->nested_join->used_tables &
~eliminated_tables)))
{
continue;
}