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Fix SHOW EXPLAIN for UNIONs.

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This commit is contained in:
Sergey Petrunya
2011-10-27 01:12:02 +04:00
parent 2bf31b0941
commit b7a340eeb0
3 changed files with 88 additions and 68 deletions
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148
sql/sql_select.cc
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@ -20425,6 +20425,83 @@ void JOIN::clear()
}
}
int print_fake_select_lex_join(select_result_sink *result, bool on_the_fly,
SELECT_LEX *select_lex, uint8 select_options)
{
const CHARSET_INFO *cs= system_charset_info;
Item *item_null= new Item_null();
List<Item> item_list;
if (on_the_fly)
select_lex->set_explain_type(on_the_fly); //psergey
/*
here we assume that the query will return at least two rows, so we
show "filesort" in EXPLAIN. Of course, sometimes we'll be wrong
and no filesort will be actually done, but executing all selects in
the UNION to provide precise EXPLAIN information will hardly be
appreciated :)
*/
char table_name_buffer[SAFE_NAME_LEN];
item_list.empty();
/* id */
item_list.push_back(new Item_null);
/* select_type */
item_list.push_back(new Item_string(select_lex->type,
strlen(select_lex->type),
cs));
/* table */
{
SELECT_LEX *sl= select_lex->master_unit()->first_select();
uint len= 6, lastop= 0;
memcpy(table_name_buffer, STRING_WITH_LEN("<union"));
for (; sl && len + lastop + 5 < NAME_LEN; sl= sl->next_select())
{
len+= lastop;
lastop= my_snprintf(table_name_buffer + len, NAME_LEN - len,
"%u,", sl->select_number);
}
if (sl || len + lastop >= NAME_LEN)
{
memcpy(table_name_buffer + len, STRING_WITH_LEN("...>") + 1);
len+= 4;
}
else
{
len+= lastop;
table_name_buffer[len - 1]= '>'; // change ',' to '>'
}
item_list.push_back(new Item_string(table_name_buffer, len, cs));
}
/* partitions */
if (/*join->thd->lex->describe*/ select_options & DESCRIBE_PARTITIONS)
item_list.push_back(item_null);
/* type */
item_list.push_back(new Item_string(join_type_str[JT_ALL],
strlen(join_type_str[JT_ALL]),
cs));
/* possible_keys */
item_list.push_back(item_null);
/* key*/
item_list.push_back(item_null);
/* key_len */
item_list.push_back(item_null);
/* ref */
item_list.push_back(item_null);
/* in_rows */
if (select_options & DESCRIBE_EXTENDED)
item_list.push_back(item_null);
/* rows */
item_list.push_back(item_null);
/* extra */
if (select_lex->master_unit()->global_parameters->order_list.first)
item_list.push_back(new Item_string("Using filesort",
14, cs));
else
item_list.push_back(new Item_string("", 0, cs));
if (result->send_data(item_list))
return 1;
return 0;
}
/**
EXPLAIN handling.
@ -20483,74 +20560,9 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
}
else if (join->select_lex == join->unit->fake_select_lex)
{
if (on_the_fly)
join->select_lex->set_explain_type(on_the_fly); //psergey
/*
here we assume that the query will return at least two rows, so we
show "filesort" in EXPLAIN. Of course, sometimes we'll be wrong
and no filesort will be actually done, but executing all selects in
the UNION to provide precise EXPLAIN information will hardly be
appreciated :)
*/
char table_name_buffer[SAFE_NAME_LEN];
item_list.empty();
/* id */
item_list.push_back(new Item_null);
/* select_type */
item_list.push_back(new Item_string(join->select_lex->type,
strlen(join->select_lex->type),
cs));
/* table */
{
SELECT_LEX *sl= join->unit->first_select();
uint len= 6, lastop= 0;
memcpy(table_name_buffer, STRING_WITH_LEN("<union"));
for (; sl && len + lastop + 5 < NAME_LEN; sl= sl->next_select())
{
len+= lastop;
lastop= my_snprintf(table_name_buffer + len, NAME_LEN - len,
"%u,", sl->select_number);
}
if (sl || len + lastop >= NAME_LEN)
{
memcpy(table_name_buffer + len, STRING_WITH_LEN("...>") + 1);
len+= 4;
}
else
{
len+= lastop;
table_name_buffer[len - 1]= '>'; // change ',' to '>'
}
item_list.push_back(new Item_string(table_name_buffer, len, cs));
}
/* partitions */
if (join->thd->lex->describe & DESCRIBE_PARTITIONS)
item_list.push_back(item_null);
/* type */
item_list.push_back(new Item_string(join_type_str[JT_ALL],
strlen(join_type_str[JT_ALL]),
cs));
/* possible_keys */
item_list.push_back(item_null);
/* key*/
item_list.push_back(item_null);
/* key_len */
item_list.push_back(item_null);
/* ref */
item_list.push_back(item_null);
/* in_rows */
if (join->thd->lex->describe & DESCRIBE_EXTENDED)
item_list.push_back(item_null);
/* rows */
item_list.push_back(item_null);
/* extra */
if (join->unit->global_parameters->order_list.first)
item_list.push_back(new Item_string("Using filesort",
14, cs));
else
item_list.push_back(new Item_string("", 0, cs));
if (result->send_data(item_list))
if (print_fake_select_lex_join(result, on_the_fly,
join->select_lex,
join->thd->lex->describe))
error= 1;
}
else if (!join->select_lex->master_unit()->derived ||