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/*
Copyright (c) 2013 Monty Program Ab
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#ifdef USE_PRAGMA_IMPLEMENTATION
#pragma implementation // gcc: Class implementation
#endif
#include <my_global.h>
#include "sql_priv.h"
#include "sql_select.h"
Explain_query::Explain_query(THD *thd_arg) :
upd_del_plan(NULL), insert_plan(NULL), thd(thd_arg), apc_enabled(false)
{
operations= 0;
}
Explain_query::~Explain_query()
{
if (apc_enabled)
thd->apc_target.disable();
delete upd_del_plan;
delete insert_plan;
uint i;
for (i= 0 ; i < unions.elements(); i++)
delete unions.at(i);
for (i= 0 ; i < selects.elements(); i++)
delete selects.at(i);
}
Explain_node *Explain_query::get_node(uint select_id)
{
Explain_union *u;
if ((u= get_union(select_id)))
return u;
else
return get_select(select_id);
}
Explain_union *Explain_query::get_union(uint select_id)
{
return (unions.elements() > select_id) ? unions.at(select_id) : NULL;
}
Explain_select *Explain_query::get_select(uint select_id)
{
return (selects.elements() > select_id) ? selects.at(select_id) : NULL;
}
void Explain_query::add_node(Explain_node *node)
{
uint select_id;
operations++;
if (node->get_type() == Explain_node::EXPLAIN_UNION)
{
Explain_union *u= (Explain_union*)node;
select_id= u->get_select_id();
if (unions.elements() <= select_id)
unions.resize(MY_MAX(select_id+1, unions.elements()*2), NULL);
Explain_union *old_node;
if ((old_node= get_union(select_id)))
delete old_node;
unions.at(select_id)= u;
}
else
{
Explain_select *sel= (Explain_select*)node;
if (sel->select_id == FAKE_SELECT_LEX_ID)
{
DBUG_ASSERT(0); // this is a "fake select" from a UNION.
}
else
{
select_id= sel->select_id;
Explain_select *old_node;
if (selects.elements() <= select_id)
selects.resize(MY_MAX(select_id+1, selects.elements()*2), NULL);
if ((old_node= get_select(select_id)))
delete old_node;
selects.at(select_id)= sel;
}
}
}
void Explain_query::add_insert_plan(Explain_insert *insert_plan_arg)
{
insert_plan= insert_plan_arg;
query_plan_ready();
}
void Explain_query::add_upd_del_plan(Explain_update *upd_del_plan_arg)
{
upd_del_plan= upd_del_plan_arg;
query_plan_ready();
}
void Explain_query::query_plan_ready()
{
if (!apc_enabled)
thd->apc_target.enable();
apc_enabled= true;
}
/*
Send EXPLAIN output to the client.
*/
int Explain_query::send_explain(THD *thd)
{
select_result *result;
LEX *lex= thd->lex;
if (!(result= new select_send()) ||
thd->send_explain_fields(result))
return 1;
int res;
if ((res= print_explain(result, lex->describe)))
result->abort_result_set();
else
result->send_eof();
return res;
}
/*
The main entry point to print EXPLAIN of the entire query
*/
int Explain_query::print_explain(select_result_sink *output,
uint8 explain_flags)
{
if (upd_del_plan)
{
upd_del_plan->print_explain(this, output, explain_flags);
return 0;
}
else if (insert_plan)
{
insert_plan->print_explain(this, output, explain_flags);
return 0;
}
else
{
/* Start printing from node with id=1 */
Explain_node *node= get_node(1);
if (!node)
return 1; /* No query plan */
return node->print_explain(this, output, explain_flags);
}
}
bool print_explain_query(LEX *lex, THD *thd, String *str)
{
return lex->explain->print_explain_str(thd, str);
}
/*
Return tabular EXPLAIN output as a text string
*/
bool Explain_query::print_explain_str(THD *thd, String *out_str)
{
List<Item> fields;
thd->make_explain_field_list(fields);
select_result_text_buffer output_buf(thd);
output_buf.send_result_set_metadata(fields, thd->lex->describe);
if (print_explain(&output_buf, thd->lex->describe))
return true;
output_buf.save_to(out_str);
return false;
}
static void push_str(List<Item> *item_list, const char *str)
{
item_list->push_back(new Item_string_sys(str));
}
static void push_string(List<Item> *item_list, String *str)
{
item_list->push_back(new Item_string_sys(str->ptr(), str->length()));
}
int Explain_union::print_explain(Explain_query *query,
select_result_sink *output,
uint8 explain_flags)
{
char table_name_buffer[SAFE_NAME_LEN];
/* print all UNION children, in order */
for (int i= 0; i < (int) union_members.elements(); i++)
{
Explain_select *sel= query->get_select(union_members.at(i));
sel->print_explain(query, output, explain_flags);
}
/* Print a line with "UNION RESULT" */
List<Item> item_list;
Item *item_null= new Item_null();
/* `id` column */
item_list.push_back(item_null);
/* `select_type` column */
push_str(&item_list, fake_select_type);
/* `table` column: something like "<union1,2>" */
{
uint childno= 0;
uint len= 6, lastop= 0;
memcpy(table_name_buffer, STRING_WITH_LEN("<union"));
for (; childno < union_members.elements() && len + lastop + 5 < NAME_LEN;
childno++)
{
len+= lastop;
lastop= my_snprintf(table_name_buffer + len, NAME_LEN - len,
"%u,", union_members.at(childno));
}
if (childno < union_members.elements() || 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_sys(table_name_buffer, len));
}
/* `partitions` column */
if (explain_flags & DESCRIBE_PARTITIONS)
item_list.push_back(item_null);
/* `type` column */
push_str(&item_list, join_type_str[JT_ALL]);
/* `possible_keys` column */
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);
/* `rows` */
item_list.push_back(item_null);
/* `filtered` */
if (explain_flags & DESCRIBE_EXTENDED)
item_list.push_back(item_null);
/* `Extra` */
StringBuffer<256> extra_buf;
if (using_filesort)
{
extra_buf.append(STRING_WITH_LEN("Using filesort"));
}
item_list.push_back(new Item_string_sys(extra_buf.ptr(), extra_buf.length()));
//output->unit.offset_limit_cnt= 0;
if (output->send_data(item_list))
return 1;
/*
Print all subquery children (UNION children have already been printed at
the start of this function)
*/
return print_explain_for_children(query, output, explain_flags);
}
/*
Print EXPLAINs for all children nodes (i.e. for subqueries)
*/
int Explain_node::print_explain_for_children(Explain_query *query,
select_result_sink *output,
uint8 explain_flags)
{
for (int i= 0; i < (int) children.elements(); i++)
{
Explain_node *node= query->get_node(children.at(i));
if (node->print_explain(query, output, explain_flags))
return 1;
}
return 0;
}
Explain_select::~Explain_select()
{
if (join_tabs)
{
for (uint i= 0; i< n_join_tabs; i++)
delete join_tabs[i];
my_free(join_tabs);
}
}
int Explain_select::print_explain(Explain_query *query,
select_result_sink *output,
uint8 explain_flags)
{
if (message)
{
List<Item> item_list;
Item *item_null= new Item_null();
item_list.push_back(new Item_int((int32) select_id));
item_list.push_back(new Item_string_sys(select_type));
for (uint i=0 ; i < 7; i++)
item_list.push_back(item_null);
if (explain_flags & DESCRIBE_PARTITIONS)
item_list.push_back(item_null);
if (explain_flags & DESCRIBE_EXTENDED)
item_list.push_back(item_null);
item_list.push_back(new Item_string_sys(message));
if (output->send_data(item_list))
return 1;
}
else
{
bool using_tmp= using_temporary;
bool using_fs= using_filesort;
for (uint i=0; i< n_join_tabs; i++)
{
join_tabs[i]->print_explain(output, explain_flags, select_id,
select_type, using_tmp, using_fs);
if (i == 0)
{
/*
"Using temporary; Using filesort" should only be shown near the 1st
table
*/
using_tmp= false;
using_fs= false;
}
}
}
return print_explain_for_children(query, output, explain_flags);
}
void Explain_table_access::push_extra(enum explain_extra_tag extra_tag)
{
extra_tags.append(extra_tag);
}
int Explain_table_access::print_explain(select_result_sink *output, uint8 explain_flags,
uint select_id, const char *select_type,
bool using_temporary, bool using_filesort)
{
const CHARSET_INFO *cs= system_charset_info;
const char *hash_key_prefix= "#hash#";
bool is_hj= (type == JT_HASH || type == JT_HASH_NEXT ||
type == JT_HASH_RANGE || type == JT_HASH_INDEX_MERGE);
List<Item> item_list;
Item *item_null= new Item_null();
if (sjm_nest_select_id)
select_id= sjm_nest_select_id;
/* `id` column */
item_list.push_back(new Item_int((int32) select_id));
/* `select_type` column */
if (sjm_nest_select_id)
push_str(&item_list, "MATERIALIZED");
else
push_str(&item_list, select_type);
/* `table` column */
push_string(&item_list, &table_name);
/* `partitions` column */
if (explain_flags & DESCRIBE_PARTITIONS)
{
if (used_partitions_set)
{
push_string(&item_list, &used_partitions);
}
else
item_list.push_back(item_null);
}
/* `type` column */
push_str(&item_list, join_type_str[type]);
/* `possible_keys` column */
if (possible_keys_str.length() > 0)
push_string(&item_list, &possible_keys_str);
else
item_list.push_back(item_null);
/* `key` */
StringBuffer<64> key_str;
if (key.get_key_name())
{
if (is_hj)
key_str.append(hash_key_prefix, strlen(hash_key_prefix), cs);
key_str.append(key.get_key_name());
if (is_hj && type != JT_HASH)
key_str.append(':');
}
if (quick_info)
{
StringBuffer<64> buf2;
quick_info->print_key(&buf2);
key_str.append(buf2);
}
if (type == JT_HASH_NEXT)
key_str.append(hash_next_key.get_key_name());
if (key_str.length() > 0)
push_string(&item_list, &key_str);
else
item_list.push_back(item_null);
/* `key_len` */
StringBuffer<64> key_len_str;
if (key.get_key_len() != (uint)-1)
{
char buf[64];
size_t length;
length= longlong10_to_str(key.get_key_len(), buf, 10) - buf;
key_len_str.append(buf, length);
if (is_hj && type != JT_HASH)
key_len_str.append(':');
}
if (quick_info)
{
StringBuffer<64> buf2;
quick_info->print_key_len(&buf2);
key_len_str.append(buf2);
}
if (type == JT_HASH_NEXT)
{
char buf[64];
size_t length;
length= longlong10_to_str(hash_next_key.get_key_len(), buf, 10) - buf;
key_len_str.append(buf, length);
}
if (key_len_str.length() > 0)
push_string(&item_list, &key_len_str);
else
item_list.push_back(item_null);
/* `ref` */
if (ref_set)
push_string(&item_list, &ref);
else
item_list.push_back(item_null);
/* `rows` */
if (rows_set)
{
item_list.push_back(new Item_int((longlong) (ulonglong) rows,
MY_INT64_NUM_DECIMAL_DIGITS));
}
else
item_list.push_back(item_null);
/* `filtered` */
if (explain_flags & DESCRIBE_EXTENDED)
{
if (filtered_set)
{
item_list.push_back(new Item_float(filtered, 2));
}
else
item_list.push_back(item_null);
}
/* `Extra` */
StringBuffer<256> extra_buf;
bool first= true;
for (int i=0; i < (int)extra_tags.elements(); i++)
{
if (first)
first= false;
else
extra_buf.append(STRING_WITH_LEN("; "));
append_tag_name(&extra_buf, extra_tags.at(i));
}
if (using_temporary)
{
if (first)
first= false;
else
extra_buf.append(STRING_WITH_LEN("; "));
extra_buf.append(STRING_WITH_LEN("Using temporary"));
}
if (using_filesort)
{
if (first)
first= false;
else
extra_buf.append(STRING_WITH_LEN("; "));
extra_buf.append(STRING_WITH_LEN("Using filesort"));
}
item_list.push_back(new Item_string_sys(extra_buf.ptr(), extra_buf.length()));
if (output->send_data(item_list))
return 1;
return 0;
}
/*
Elements in this array match members of enum Extra_tag, defined in
sql_explain.h
*/
const char * extra_tag_text[]=
{
"ET_none",
"Using index condition",
"Using index condition(BKA)",
"Using ", // special handling
"Range checked for each record (index map: 0x", // special handling
"Using where with pushed condition",
"Using where",
"Not exists",
"Using index",
"Full scan on NULL key",
"Skip_open_table",
"Open_frm_only",
"Open_full_table",
"Scanned 0 databases",
"Scanned 1 database",
"Scanned all databases",
"Using index for group-by", // special handling
"USING MRR: DONT PRINT ME", // special handling
"Distinct",
"LooseScan",
"Start temporary",
"End temporary",
"FirstMatch", // special handling
"Using join buffer", // special handling
"const row not found",
"unique row not found",
"Impossible ON condition"
};
void Explain_table_access::append_tag_name(String *str, enum explain_extra_tag tag)
{
switch (tag) {
case ET_USING:
{
// quick select
str->append(STRING_WITH_LEN("Using "));
quick_info->print_extra(str);
break;
}
case ET_RANGE_CHECKED_FOR_EACH_RECORD:
{
/* 4 bits per 1 hex digit + terminating '\0' */
char buf[MAX_KEY / 4 + 1];
str->append(STRING_WITH_LEN("Range checked for each "
"record (index map: 0x"));
str->append(range_checked_map.print(buf));
str->append(')');
break;
}
case ET_USING_MRR:
{
str->append(mrr_type);
break;
}
case ET_USING_JOIN_BUFFER:
{
str->append(extra_tag_text[tag]);
str->append(STRING_WITH_LEN(" ("));
const char *buffer_type= bka_type.incremental ? "incremental" : "flat";
str->append(buffer_type);
str->append(STRING_WITH_LEN(", "));
str->append(bka_type.join_alg);
str->append(STRING_WITH_LEN(" join"));
str->append(STRING_WITH_LEN(")"));
if (bka_type.mrr_type.length())
str->append(bka_type.mrr_type);
break;
}
case ET_FIRST_MATCH:
{
if (firstmatch_table_name.length())
{
str->append("FirstMatch(");
str->append(firstmatch_table_name);
str->append(")");
}
else
str->append(extra_tag_text[tag]);
break;
}
case ET_USING_INDEX_FOR_GROUP_BY:
{
str->append(extra_tag_text[tag]);
if (loose_scan_is_scanning)
str->append(" (scanning)");
break;
}
default:
str->append(extra_tag_text[tag]);
}
}
/*
This is called for top-level Explain_quick_select only. The point of this
function is:
- index_merge should print $index_merge_type (child, ...)
- 'range' should not print anything.
*/
void Explain_quick_select::print_extra(String *str)
{
if (quick_type == QUICK_SELECT_I::QS_TYPE_RANGE ||
quick_type == QUICK_SELECT_I::QS_TYPE_RANGE_DESC ||
quick_type == QUICK_SELECT_I::QS_TYPE_GROUP_MIN_MAX)
{
/* print nothing */
}
else
print_extra_recursive(str);
}
void Explain_quick_select::print_extra_recursive(String *str)
{
if (quick_type == QUICK_SELECT_I::QS_TYPE_RANGE ||
quick_type == QUICK_SELECT_I::QS_TYPE_RANGE_DESC)
{
str->append(range.get_key_name());
}
else
{
str->append(get_name_by_type());
str->append('(');
List_iterator_fast<Explain_quick_select> it (children);
Explain_quick_select* child;
bool first= true;
while ((child = it++))
{
if (first)
first= false;
else
str->append(',');
child->print_extra_recursive(str);
}
str->append(')');
}
}
const char * Explain_quick_select::get_name_by_type()
{
switch (quick_type) {
case QUICK_SELECT_I::QS_TYPE_INDEX_MERGE:
return "sort_union";
case QUICK_SELECT_I::QS_TYPE_ROR_UNION:
return "union";
case QUICK_SELECT_I::QS_TYPE_ROR_INTERSECT:
return "intersect";
case QUICK_SELECT_I::QS_TYPE_INDEX_INTERSECT:
return "sort_intersect";
default:
DBUG_ASSERT(0);
return "unknown quick select type";
}
}
/*
This prints a comma-separated list of used indexes, ignoring nesting
*/
void Explain_quick_select::print_key(String *str)
{
if (quick_type == QUICK_SELECT_I::QS_TYPE_RANGE ||
quick_type == QUICK_SELECT_I::QS_TYPE_RANGE_DESC ||
quick_type == QUICK_SELECT_I::QS_TYPE_GROUP_MIN_MAX)
{
if (str->length() > 0)
str->append(',');
str->append(range.get_key_name());
}
else
{
List_iterator_fast<Explain_quick_select> it (children);
Explain_quick_select* child;
while ((child = it++))
{
child->print_key(str);
}
}
}
/*
This prints a comma-separated list of used key_lengths, ignoring nesting
*/
void Explain_quick_select::print_key_len(String *str)
{
if (quick_type == QUICK_SELECT_I::QS_TYPE_RANGE ||
quick_type == QUICK_SELECT_I::QS_TYPE_RANGE_DESC ||
quick_type == QUICK_SELECT_I::QS_TYPE_GROUP_MIN_MAX)
{
char buf[64];
size_t length;
length= longlong10_to_str(range.get_key_len(), buf, 10) - buf;
if (str->length() > 0)
str->append(',');
str->append(buf, length);
}
else
{
List_iterator_fast<Explain_quick_select> it (children);
Explain_quick_select* child;
while ((child = it++))
{
child->print_key_len(str);
}
}
}
int Explain_delete::print_explain(Explain_query *query,
select_result_sink *output,
uint8 explain_flags)
{
if (deleting_all_rows)
{
const char *msg= "Deleting all rows";
int res= print_explain_message_line(output, explain_flags,
1 /*select number*/,
select_type, &rows, msg);
return res;
}
else
{
return Explain_update::print_explain(query, output, explain_flags);
}
}
int Explain_update::print_explain(Explain_query *query,
select_result_sink *output,
uint8 explain_flags)
{
StringBuffer<64> key_buf;
StringBuffer<64> key_len_buf;
StringBuffer<64> extra_str;
if (impossible_where || no_partitions)
{
const char *msg= impossible_where ?
"Impossible WHERE" :
"No matching rows after partition pruning";
int res= print_explain_message_line(output, explain_flags,
1 /*select number*/,
select_type,
NULL, /* rows */
msg);
return res;
}
if (quick_info)
{
quick_info->print_key(&key_buf);
quick_info->print_key_len(&key_len_buf);
StringBuffer<64> quick_buf;
quick_info->print_extra(&quick_buf);
if (quick_buf.length())
{
extra_str.append(STRING_WITH_LEN("Using "));
extra_str.append(quick_buf);
}
}
else
{
key_buf.copy(key_str);
key_len_buf.copy(key_len_str);
}
if (using_where)
{
if (extra_str.length() !=0)
extra_str.append(STRING_WITH_LEN("; "));
extra_str.append(STRING_WITH_LEN("Using where"));
}
if (mrr_type.length() != 0)
{
if (extra_str.length() !=0)
extra_str.append(STRING_WITH_LEN("; "));
extra_str.append(mrr_type);
}
if (using_filesort)
{
if (extra_str.length() !=0)
extra_str.append(STRING_WITH_LEN("; "));
extra_str.append(STRING_WITH_LEN("Using filesort"));
}
if (using_io_buffer)
{
if (extra_str.length() !=0)
extra_str.append(STRING_WITH_LEN("; "));
extra_str.append(STRING_WITH_LEN("Using buffer"));
}
/*
Single-table DELETE commands do not do "Using temporary".
"Using index condition" is also not possible (which is an unjustified limitation)
*/
print_explain_row(output, explain_flags,
1, /* id */
select_type,
table_name.c_ptr(),
used_partitions_set? used_partitions.c_ptr() : NULL,
jtype,
possible_keys_line.length()? possible_keys_line.c_ptr(): NULL,
key_buf.length()? key_buf.c_ptr() : NULL,
key_len_buf.length() ? key_len_buf.c_ptr() : NULL,
NULL, /* 'ref' is always NULL in single-table EXPLAIN DELETE */
&rows,
extra_str.c_ptr_safe());
return print_explain_for_children(query, output, explain_flags);
}
int Explain_insert::print_explain(Explain_query *query,
select_result_sink *output,
uint8 explain_flags)
{
const char *select_type="INSERT";
print_explain_row(output, explain_flags,
1, /* id */
select_type,
table_name.c_ptr(),
NULL, // partitions
JT_ALL,
NULL, // possible_keys
NULL, // key
NULL, // key_len
NULL, // ref
NULL, // rows
NULL);
return print_explain_for_children(query, output, explain_flags);
}
void delete_explain_query(LEX *lex)
{
delete lex->explain;
lex->explain= NULL;
}
void create_explain_query(LEX *lex, MEM_ROOT *mem_root)
{
DBUG_ASSERT(!lex->explain);
lex->explain= new Explain_query(lex->thd);
DBUG_ASSERT(mem_root == current_thd->mem_root);
lex->explain->mem_root= mem_root;
}
void create_explain_query_if_not_exists(LEX *lex, MEM_ROOT *mem_root)
{
if (!lex->explain)
create_explain_query(lex, mem_root);
}
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