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bug: move one_storage_engine checking loop
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down to the point where all tables are already known
(and subqueries converted to joins, if needed)
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@vuvova
vuvova committed Oct 5, 2015
1 parent c93ac0a commit 8dff1aa
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Showing 2 changed files with 96 additions and 100 deletions.
193 changes: 96 additions & 97 deletions sql/sql_select.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -759,12 +759,6 @@ JOIN::prepare(Item ***rref_pointer_array,

TABLE_LIST *tbl;
List_iterator_fast<TABLE_LIST> li(select_lex->leaf_tables);
/*
If all tables comes from the same storage engine, one_storage_engine will
be set to point to the handlerton of this engine.
*/
one_storage_engine= 0;
uint table_loop_count= 0;
while ((tbl= li++))
{
/*
Expand All @@ -776,17 +770,8 @@ JOIN::prepare(Item ***rref_pointer_array,
Note: this loop doesn't touch tables inside merged semi-joins, because
subquery-to-semijoin conversion has not been done yet. This is intended.
*/
if (tbl->table)
{
if (mixed_implicit_grouping)
tbl->table->maybe_null= 1;
if (!table_loop_count++)
one_storage_engine= tbl->table->file->ht;
else if (one_storage_engine != tbl->table->file->ht)
one_storage_engine= 0;
}
else
one_storage_engine= 0;
if (mixed_implicit_grouping && tbl->table)
tbl->table->maybe_null= 1;
}

if ((wild_num && setup_wild(thd, tables_list, fields_list, &all_fields,
Expand Down Expand Up @@ -1914,92 +1899,106 @@ JOIN::optimize_inner()
group by handler to evaluate the group by
*/

if ((tmp_table_param.sum_func_count || group_list) && !procedure &&
(one_storage_engine && one_storage_engine->create_group_by))
if ((tmp_table_param.sum_func_count || group_list) && !procedure)
{
/* Check if the storage engine can intercept the query */
group_by_handler *gbh= one_storage_engine->create_group_by(thd, &all_fields,
tables_list, group_list, order, conds, having);
if (gbh)
/*
At the moment we only support push down for queries where
all tables are in the same storage engine
*/
TABLE_LIST *tbl= tables_list;
handlerton *ht= tbl && tbl->table ? tbl->table->file->ht : 0;
for (tbl= tbl->next_local; ht && tbl; tbl= tbl->next_local)
{
pushdown_query= new (thd->mem_root) Pushdown_query(select_lex, gbh);
uint handler_flags= gbh->flags();
int err;
if (!tbl->table || tbl->table->file->ht != ht)
ht= 0;
}

/*
We must store rows in the tmp table if we need to do an ORDER BY
or DISTINCT and the storage handler can't handle it.
*/
need_tmp= ((!(handler_flags & GROUP_BY_ORDER_BY) &&
(order || group_list)) ||
(!(handler_flags & GROUP_BY_DISTINCT) && select_distinct));
tmp_table_param.hidden_field_count= (all_fields.elements -
fields_list.elements);
if (!(exec_tmp_table1=
create_tmp_table(thd, &tmp_table_param, all_fields,
0, handler_flags & GROUP_BY_DISTINCT ?
0 : select_distinct, 1,
select_options, HA_POS_ERROR, "",
!need_tmp,
(!order ||
(handler_flags & GROUP_BY_ORDER_BY)))))
DBUG_RETURN(1);
if (ht && ht->create_group_by)
{
/* Check if the storage engine can intercept the query */
group_by_handler *gbh= ht->create_group_by(thd, &all_fields,
tables_list, group_list, order, conds, having);
if (gbh)
{
pushdown_query= new (thd->mem_root) Pushdown_query(select_lex, gbh);
uint handler_flags= gbh->flags();
int err;

/*
Setup reference fields, used by summary functions and group by fields,
to point to the temporary table.
The actual switching to the temporary tables fields for HAVING
and ORDER BY is done in do_select() by calling
set_items_ref_array(items1).
*/
init_items_ref_array();
items1= items0 + all_fields.elements;
if (change_to_use_tmp_fields(thd, items1,
tmp_fields_list1, tmp_all_fields1,
fields_list.elements, all_fields))
DBUG_RETURN(1);
/*
We must store rows in the tmp table if we need to do an ORDER BY
or DISTINCT and the storage handler can't handle it.
*/
need_tmp= ((!(handler_flags & GROUP_BY_ORDER_BY) &&
(order || group_list)) ||
(!(handler_flags & GROUP_BY_DISTINCT) && select_distinct));
tmp_table_param.hidden_field_count= (all_fields.elements -
fields_list.elements);
if (!(exec_tmp_table1=
create_tmp_table(thd, &tmp_table_param, all_fields, 0,
handler_flags & GROUP_BY_DISTINCT ?
0 : select_distinct, 1,
select_options, HA_POS_ERROR, "",
!need_tmp,
(!order ||
(handler_flags & GROUP_BY_ORDER_BY)))))
DBUG_RETURN(1);

/* Give storage engine access to temporary table */
if ((err= gbh->ha_init(exec_tmp_table1, having, order)))
{
gbh->print_error(err, MYF(0));
DBUG_RETURN(1);
/*
Setup reference fields, used by summary functions and group by fields,
to point to the temporary table.
The actual switching to the temporary tables fields for HAVING
and ORDER BY is done in do_select() by calling
set_items_ref_array(items1).
*/
init_items_ref_array();
items1= items0 + all_fields.elements;
if (change_to_use_tmp_fields(thd, items1,
tmp_fields_list1, tmp_all_fields1,
fields_list.elements, all_fields))
DBUG_RETURN(1);

/* Give storage engine access to temporary table */
if ((err= gbh->ha_init(exec_tmp_table1, having, order)))
{
gbh->print_error(err, MYF(0));
DBUG_RETURN(1);
}
pushdown_query->store_data_in_temp_table= need_tmp;
pushdown_query->having= having;
/*
If no ORDER BY clause was specified explicitly, we should sort things
according to the group_by
*/
if (!order)
order= group_list;
/*
Group by and having is calculated by the group_by handler.
Reset the group by and having
*/
group= 0; group_list= 0;
having= tmp_having= 0;
/*
Select distinct is handled by handler or by creating an unique index
over all fields in the temporary table
*/
select_distinct= 0;
if (handler_flags & GROUP_BY_ORDER_BY)
order= 0;
tmp_table_param.field_count+= tmp_table_param.sum_func_count;
tmp_table_param.sum_func_count= 0;

/* Remember information about the original join */
original_join_tab= join_tab;
original_table_count= table_count;

/* Set up one join tab to get sorting to work */
const_tables= 0;
table_count= 1;
join_tab= (JOIN_TAB*) thd->calloc(sizeof(JOIN_TAB));
join_tab[0].table= exec_tmp_table1;

DBUG_RETURN(thd->is_fatal_error);
}
pushdown_query->store_data_in_temp_table= need_tmp;
pushdown_query->having= having;
/*
If no ORDER BY clause was specified explicitly, we should sort things
according to the group_by
*/
if (!order)
order= group_list;
/*
Group by and having is calculated by the group_by handler.
Reset the group by and having
*/
group= 0; group_list= 0;
having= tmp_having= 0;
/*
Select distinct is handled by handler or by creating an unique index
over all fields in the temporary table
*/
select_distinct= 0;
if (handler_flags & GROUP_BY_ORDER_BY)
order= 0;
tmp_table_param.field_count+= tmp_table_param.sum_func_count;
tmp_table_param.sum_func_count= 0;

/* Remember information about the original join */
original_join_tab= join_tab;
original_table_count= table_count;

/* Set up one join tab to get sorting to work */
const_tables= 0;
table_count= 1;
join_tab= (JOIN_TAB*) thd->calloc(sizeof(JOIN_TAB));
join_tab[0].table= exec_tmp_table1;

DBUG_RETURN(thd->is_fatal_error);
}
}

Expand Down
3 changes: 0 additions & 3 deletions sql/sql_select.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1087,8 +1087,6 @@ class JOIN :public Sql_alloc
/* Finally picked QEP. This is result of join optimization */
POSITION *best_positions;

/* points to a storage engine if all tables comes from the storage engine */
handlerton *one_storage_engine;
Pushdown_query *pushdown_query;
JOIN_TAB *original_join_tab;
uint original_table_count;
Expand Down Expand Up @@ -1391,7 +1389,6 @@ class JOIN :public Sql_alloc
group_optimized_away= 0;
no_rows_in_result_called= 0;
positions= best_positions= 0;
one_storage_engine= 0;
pushdown_query= 0;
original_join_tab= 0;
do_select_call_count= 0;
Expand Down

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