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MDEV-3798: EXPLAIN UPDATE/DELETE

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- Generate correct contents of `Extra` column for UPDATEs/DELETEs that use quick selects
- UPDATEs with used_key_is_modified=true will show "Using buffer"
This commit is contained in:
Sergey Petrunya 2013-10-09 09:40:33 +04:00
parent 69e6a2bb22
commit 161d687594
5 changed files with 73 additions and 20 deletions
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8
sql/sql_delete.cc
View File

@ -142,14 +142,16 @@ void Update_plan::save_explain_data_intern(Explain_query *query,
explain->using_where= test(select && select->cond);
explain->using_filesort= using_filesort;
explain->using_io_buffer= using_io_buffer;
make_possible_keys_line(table, possible_keys, &explain->possible_keys_line);
explain->quick_info= NULL;
/* Calculate key_len */
if (select && select->quick)
{
select->quick->add_keys_and_lengths(&explain->key_str,
&explain->key_len_str);
explain->quick_info= select->quick->get_explain(mem_root);
}
else
{
@ -218,7 +220,7 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
killed_state killed_status= NOT_KILLED;
THD::enum_binlog_query_type query_type= THD::ROW_QUERY_TYPE;
bool with_select= !select_lex->item_list.is_empty();
Delete_plan query_plan;
Delete_plan query_plan(thd->mem_root);
query_plan.index= MAX_KEY;
query_plan.using_filesort= FALSE;
DBUG_ENTER("mysql_delete");

42
sql/sql_explain.cc
View File

@ -793,6 +793,8 @@ 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)
{
@ -807,8 +809,32 @@ int Explain_update::print_explain(Explain_query *query,
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)
{
@ -816,7 +842,7 @@ int Explain_update::print_explain(Explain_query *query,
extra_str.append(STRING_WITH_LEN("; "));
extra_str.append(mrr_type);
}
if (using_filesort)
{
if (extra_str.length() !=0)
@ -824,6 +850,13 @@ int Explain_update::print_explain(Explain_query *query,
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)
@ -836,8 +869,8 @@ int Explain_update::print_explain(Explain_query *query,
used_partitions_set? used_partitions.c_ptr() : NULL,
jtype,
possible_keys_line.length()? possible_keys_line.c_ptr(): NULL,
key_str.length()? key_str.c_ptr() : NULL,
key_len_str.length() ? key_len_str.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());
@ -846,7 +879,8 @@ int Explain_update::print_explain(Explain_query *query,
}
int Explain_insert::print_explain(Explain_query *query, select_result_sink *output,
int Explain_insert::print_explain(Explain_query *query,
select_result_sink *output,
uint8 explain_flags)
{
const char *select_type="INSERT";

3
sql/sql_explain.h
View File

@ -486,10 +486,13 @@ public:
StringBuffer<128> key_len_str;
StringBuffer<64> mrr_type;
Explain_quick_select *quick_info;
bool using_where;
ha_rows rows;
bool using_filesort;
bool using_io_buffer;
virtual int print_explain(Explain_query *query, select_result_sink *output,
uint8 explain_flags);

16
sql/sql_lex.h
View File

@ -2390,6 +2390,9 @@ public:
select should not be shown when printing EXPLAIN.
*/
bool updating_a_view;
/* Allocate things there */
MEM_ROOT *mem_root;
TABLE *table;
SQL_SELECT *select;
@ -2403,6 +2406,7 @@ public:
key_map possible_keys;
bool using_filesort;
bool using_io_buffer;
/* Set this plan to be a plan to do nothing because of impossible WHERE */
void set_impossible_where() { impossible_where= true; }
@ -2412,8 +2416,10 @@ public:
void save_explain_data_intern(Explain_query *query, Explain_update *eu);
virtual ~Update_plan() {}
Update_plan() :
impossible_where(false), no_partitions(false), using_filesort(false)
Update_plan(MEM_ROOT *mem_root_arg) :
impossible_where(false), no_partitions(false),
mem_root(mem_root_arg),
using_filesort(false), using_io_buffer(false)
{}
};
@ -2425,8 +2431,10 @@ class Delete_plan : public Update_plan
public:
/* Construction functions */
Delete_plan() :
deleting_all_rows(false) {}
Delete_plan(MEM_ROOT *mem_root_arg) :
Update_plan(mem_root_arg),
deleting_all_rows(false)
{}
/* Set this query plan to be a plan to make a call to h->delete_all_rows() */
void set_delete_all_rows(ha_rows rows_arg)

24
sql/sql_update.cc
View File

@ -276,7 +276,7 @@ int mysql_update(THD *thd,
ulonglong id;
List<Item> all_fields;
killed_state killed_status= NOT_KILLED;
Update_plan query_plan;
Update_plan query_plan(thd->mem_root);
query_plan.index= MAX_KEY;
query_plan.using_filesort= FALSE;
bool apc_target_enabled= false; // means was enabled *by code this function*
@ -495,6 +495,17 @@ int mysql_update(THD *thd,
query_plan.table_rows= table->file->stats.records;
query_plan.possible_keys= select? select->possible_keys: key_map(0);
if (used_key_is_modified || order ||
partition_key_modified(table, table->write_set))
{
if (order && (need_sort || used_key_is_modified))
query_plan.using_filesort= true;
else
query_plan.using_io_buffer= true;
}
query_plan.save_explain_data(thd->lex->explain);
/*
Ok, we have generated a query plan for the UPDATE.
- if we're running EXPLAIN UPDATE, goto produce explain output
@ -502,16 +513,12 @@ int mysql_update(THD *thd,
*/
if (thd->lex->describe)
goto exit_without_my_ok;
query_plan.save_explain_data(thd->lex->explain);
thd->apc_target.enable();
apc_target_enabled= true;
DBUG_EXECUTE_IF("show_explain_probe_update_exec_start",
dbug_serve_apcs(thd, 1););
if (used_key_is_modified || order ||
partition_key_modified(table, table->write_set))
if (query_plan.using_filesort || query_plan.using_io_buffer)
{
/*
We can't update table directly; We must first search after all
@ -528,7 +535,7 @@ int mysql_update(THD *thd,
table->use_all_columns();
/* note: We avoid sorting if we sort on the used index */
if (order && (need_sort || used_key_is_modified))
if (query_plan.using_filesort)
{
/*
Doing an ORDER BY; Let filesort find and sort the rows we are going
@ -1034,7 +1041,6 @@ err:
exit_without_my_ok:
DBUG_ASSERT(!apc_target_enabled);
query_plan.save_explain_data(thd->lex->explain);
int err2= thd->lex->explain->send_explain(thd);