MWL#17: Table elimination
- 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
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@ -522,7 +522,7 @@ id select_type table type possible_keys key key_len ref rows filtered Extra
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2 UNION t2 const PRIMARY PRIMARY 4 const 1 100.00
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NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL NULL
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Warnings:
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Note 1003 (select '1' AS `a`,'1' AS `b` from `test`.`t1` where ('1' = 1)) union (select '1' AS `a`,'10' AS `b` from `test`.`t2` where ('1' = 1))
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Note 1003 (select '1' AS `a`,'1' AS `b` from `test`.`t1` where 1) union (select '1' AS `a`,'10' AS `b` from `test`.`t2` where 1)
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(select * from t1 where a=5) union (select * from t2 where a=1);
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a b
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1 10
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@ -16937,18 +16937,28 @@ static void print_join(THD *thd,
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*t= ti++;
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DBUG_ASSERT(tables->elements >= 1);
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//pserey:TODO check!
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/*
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Assert that the first table in the list isn't eliminated (if it was we
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would have skipped the entire join nest)
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*/
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DBUG_ASSERT(!eliminated_tables ||
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!((*table)->table && ((*table)->table->map & eliminated_tables) ||
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(*table)->nested_join && !((*table)->nested_join->used_tables &
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~eliminated_tables)));
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(*table)->print(thd, eliminated_tables, str, query_type);
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TABLE_LIST **end= table + tables->elements;
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for (TABLE_LIST **tbl= table + 1; tbl < end; tbl++)
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{
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TABLE_LIST *curr= *tbl;
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// psergey-todo-todo:
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// base table: check
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if (curr->table && (curr->table->map & eliminated_tables) ||
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curr->nested_join && !(curr->nested_join->used_tables &
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~eliminated_tables))
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/*
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The (*) check guards againist the case of printing the query for
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CREATE VIEW. There we'll have nested_join->used_tables==0.
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*/
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if (eliminated_tables && // (*)
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(curr->table && (curr->table->map & eliminated_tables) ||
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curr->nested_join && !(curr->nested_join->used_tables &
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~eliminated_tables)))
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{
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continue;
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}
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