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MWL#90: Address review feedback part #12

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- Address review feedback in select_describe().
This commit is contained in:
Sergey Petrunya
2011-03-26 12:46:00 +03:00
parent bf894470de
commit 2071ac10fd
1 changed files with 62 additions and 24 deletions
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86
sql/sql_select.cc
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@ -6362,6 +6362,59 @@ prev_record_reads(JOIN *join, uint idx, table_map found_ref)
}
/*
Enumerate join tabs in breadth-first fashion, including const tables.
*/
JOIN_TAB *first_breadth_first_tab(JOIN *join)
{
return join->join_tab; /* There's always one (i.e. first) table */
}
JOIN_TAB *next_breadth_first_tab(JOIN *join, JOIN_TAB *tab)
{
if (!tab->bush_root_tab)
{
/* We're at top level. Get the next top-level tab */
tab++;
if (tab < join->join_tab + join->top_jtrange_tables)
return tab;
/* No more top-level tabs. Switch to enumerating SJM nest children */
tab= join->join_tab;
}
else
{
/* We're inside of an SJM nest */
if (!tab->last_leaf_in_bush)
{
/* There's one more table in the nest, return it. */
return ++tab;
}
else
{
/*
There are no more tables in this nest. Get out of it and then we'll
proceed to the next nest.
*/
tab= tab->bush_root_tab + 1;
}
}
/*
Ok, "tab" points to a top-level table, and we need to find the next SJM
nest and enter it.
*/
for (; tab < join->join_tab + join->top_jtrange_tables; tab++)
{
if (tab->bush_children)
return tab->bush_children->start;
}
return NULL;
}
JOIN_TAB *first_linear_tab(JOIN *join, enum enum_with_const_tables const_tbls)
{
JOIN_TAB *first= join->join_tab;
@ -19361,18 +19414,16 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
bool printing_materialize_nest= FALSE;
uint select_id= join->select_lex->select_number;
List_iterator<JOIN_TAB_RANGE> it(join->join_tab_ranges);
JOIN_TAB_RANGE *jt_range;
while ((jt_range= it++))
for (JOIN_TAB *tab= first_breadth_first_tab(join); tab;
tab= next_breadth_first_tab(join, tab))
{
if (jt_range != join->join_tab_ranges.head())
{
select_id= jt_range->start->emb_sj_nest->sj_subq_pred->get_identifier();
printing_materialize_nest= TRUE;
}
if (tab->bush_root_tab)
{
JOIN_TAB *first_sibling= tab->bush_root_tab->bush_children->start;
select_id= first_sibling->emb_sj_nest->sj_subq_pred->get_identifier();
printing_materialize_nest= TRUE;
}
for (JOIN_TAB *tab= jt_range->start + 0; tab < jt_range->end; tab++)
{
TABLE *table=tab->table;
TABLE_LIST *table_list= tab->table->pos_in_table_list;
char buff[512];
@ -19635,21 +19686,9 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
/* Add "filtered" field to item_list. */
if (join->thd->lex->describe & DESCRIBE_EXTENDED)
{
/*
psergey-todo:
in the code above, we cast to integer when asssigning to
examined_rows.
In the code below, we may divide original value but result of
conversion of the same value to integer, which may produce a
value that's greater than 100%, which looks very odd.
I'm not fixing this right away because that might trigger a wave
of small EXPLAIN EXTENDED output changes, which I don't have time
to deal with right now.
*/
float f= 0.0;
if (examined_rows)
f= (float) (100.0 * tab->records_read/*join->best_positions[i].records_read*/ /
examined_rows);
f= (float) (100.0 * tab->records_read / examined_rows);
item_list.push_back(new Item_float(f, 2));
}
}
@ -19845,7 +19884,6 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
if (result->send_data(item_list))
join->error= 1;
}
}
}
for (SELECT_LEX_UNIT *unit= join->select_lex->first_inner_unit();
unit;