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MDEV-13694: Wrong result upon GROUP BY with orderby_uses_equalities=on

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For the case when  the SJM scan table is the first table in the join order,
then if we want to do the sorting on the SJM scan table, then we need to
make sure that we unpack the values to base table fields in two cases:
    1) Reading the SJM table and writing the sort-keys inside the sort-buffer
    2) Reading the sorted data from the sort file
This commit is contained in:
Varun Gupta
2020-07-08 20:43:57 +05:30
parent 9701759b3d
commit 7148b84673
11 changed files with 289 additions and 64 deletions
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138
mysql-test/main/order_by.result
View File

@ -3417,7 +3417,7 @@ WHERE books.library_id = 8663 AND
books.scheduled_for_removal=0 )
ORDER BY wings.id;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY <subquery2> ALL distinct_key NULL NULL NULL 2 100.00 Using temporary; Using filesort
1 PRIMARY <subquery2> ALL distinct_key NULL NULL NULL 2 100.00 Using filesort
1 PRIMARY wings eq_ref PRIMARY PRIMARY 4 test.books.wings_id 1 100.00
2 MATERIALIZED books ref library_idx library_idx 4 const 2 100.00 Using where
Warnings:
@ -4023,4 +4023,140 @@ COUNT(DISTINCT a)
34
SET @@tmp_memory_table_size= @save_tmp_memory_table_size;
DROP TABLE t1;
#
# MDEV-13694: Wrong result upon GROUP BY with orderby_uses_equalities=on
#
CREATE TABLE t1 (a INT, b int, primary key(a));
CREATE TABLE t2 (a INT, b INT);
INSERT INTO t1 (a,b) VALUES (58,1),(96,2),(273,3),(23,4),(231,5),(525,6),
(2354,7),(321421,3),(535,2),(4535,3);
INSERT INTO t2 (a,b) VALUES (58,3),(96,3),(273,3);
# Join order should have the SJM scan table as the first table for both
# the queries with GROUP BY and ORDER BY clause.
EXPLAIN SELECT t1.a
FROM t1
WHERE t1.a IN (SELECT a FROM t2 WHERE b=3)
ORDER BY t1.a DESC;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <subquery2> ALL distinct_key NULL NULL NULL 3 Using filesort
1 PRIMARY t1 eq_ref PRIMARY PRIMARY 4 test.t2.a 1 Using index
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 3 Using where
EXPLAIN FORMAT=JSON SELECT t1.a
FROM t1
WHERE t1.a IN (SELECT a FROM t2 WHERE b=3)
ORDER BY t1.a DESC;
EXPLAIN
{
"query_block": {
"select_id": 1,
"read_sorted_file": {
"filesort": {
"sort_key": "t1.a desc",
"table": {
"table_name": "<subquery2>",
"access_type": "ALL",
"possible_keys": ["distinct_key"],
"rows": 3,
"filtered": 100,
"materialized": {
"unique": 1,
"query_block": {
"select_id": 2,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows": 3,
"filtered": 100,
"attached_condition": "t2.b = 3 and t2.a is not null"
}
}
}
}
}
},
"table": {
"table_name": "t1",
"access_type": "eq_ref",
"possible_keys": ["PRIMARY"],
"key": "PRIMARY",
"key_length": "4",
"used_key_parts": ["a"],
"ref": ["test.t2.a"],
"rows": 1,
"filtered": 100,
"using_index": true
}
}
}
SELECT t1.a
FROM t1
WHERE t1.a IN (SELECT a FROM t2 WHERE b=3)
ORDER BY t1.a DESC;
a
273
96
58
EXPLAIN SELECT t1.a, group_concat(t1.b)
FROM t1
WHERE t1.a IN (SELECT a FROM t2 WHERE b=3)
GROUP BY t1.a DESC;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <subquery2> ALL distinct_key NULL NULL NULL 3 Using filesort
1 PRIMARY t1 eq_ref PRIMARY PRIMARY 4 test.t2.a 1
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 3 Using where
EXPLAIN FORMAT=JSON SELECT t1.a, group_concat(t1.b)
FROM t1
WHERE t1.a IN (SELECT a FROM t2 WHERE b=3)
GROUP BY t1.a DESC;
EXPLAIN
{
"query_block": {
"select_id": 1,
"read_sorted_file": {
"filesort": {
"sort_key": "t1.a desc",
"table": {
"table_name": "<subquery2>",
"access_type": "ALL",
"possible_keys": ["distinct_key"],
"rows": 3,
"filtered": 100,
"materialized": {
"unique": 1,
"query_block": {
"select_id": 2,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows": 3,
"filtered": 100,
"attached_condition": "t2.b = 3 and t2.a is not null"
}
}
}
}
}
},
"table": {
"table_name": "t1",
"access_type": "eq_ref",
"possible_keys": ["PRIMARY"],
"key": "PRIMARY",
"key_length": "4",
"used_key_parts": ["a"],
"ref": ["test.t2.a"],
"rows": 1,
"filtered": 100
}
}
}
SELECT t1.a, group_concat(t1.b)
FROM t1
WHERE t1.a IN (SELECT a FROM t2 WHERE b=3)
GROUP BY t1.a DESC;
a group_concat(t1.b)
273 3
96 2
58 1
DROP TABLE t1, t2;
# End of 10.5 tests

32
mysql-test/main/order_by.test
View File

@ -2500,5 +2500,37 @@ SELECT COUNT(DISTINCT a) FROM t1;
SET @@tmp_memory_table_size= @save_tmp_memory_table_size;
DROP TABLE t1;
--echo #
--echo # MDEV-13694: Wrong result upon GROUP BY with orderby_uses_equalities=on
--echo #
CREATE TABLE t1 (a INT, b int, primary key(a));
CREATE TABLE t2 (a INT, b INT);
INSERT INTO t1 (a,b) VALUES (58,1),(96,2),(273,3),(23,4),(231,5),(525,6),
(2354,7),(321421,3),(535,2),(4535,3);
INSERT INTO t2 (a,b) VALUES (58,3),(96,3),(273,3);
--echo # Join order should have the SJM scan table as the first table for both
--echo # the queries with GROUP BY and ORDER BY clause.
let $query= SELECT t1.a
FROM t1
WHERE t1.a IN (SELECT a FROM t2 WHERE b=3)
ORDER BY t1.a DESC;
eval EXPLAIN $query;
eval EXPLAIN FORMAT=JSON $query;
eval $query;
let $query= SELECT t1.a, group_concat(t1.b)
FROM t1
WHERE t1.a IN (SELECT a FROM t2 WHERE b=3)
GROUP BY t1.a DESC;
eval EXPLAIN $query;
eval EXPLAIN FORMAT=JSON $query;
eval $query;
DROP TABLE t1, t2;
--echo # End of 10.5 tests

9
sql/filesort.cc
View File

@ -251,6 +251,9 @@ SORT_INFO *filesort(THD *thd, TABLE *table, Filesort *filesort,
param.init_for_filesort(sort_len, table, max_rows, filesort->sort_positions);
param.set_all_read_bits= filesort->set_all_read_bits;
param.unpack= filesort->unpack;
sort->addon_fields= param.addon_fields;
sort->sort_keys= param.sort_keys;
@ -883,6 +886,8 @@ static ha_rows find_all_keys(THD *thd, Sort_param *param, SQL_SELECT *select,
goto err;
}
if (param->set_all_read_bits)
sort_form->column_bitmaps_set(save_read_set, save_write_set);
DEBUG_SYNC(thd, "after_index_merge_phase1");
for (;;)
@ -890,7 +895,11 @@ static ha_rows find_all_keys(THD *thd, Sort_param *param, SQL_SELECT *select,
if (quick_select)
error= select->quick->get_next();
else /* Not quick-select */
{
error= file->ha_rnd_next(sort_form->record[0]);
if (param->unpack)
param->unpack(sort_form);
}
if (unlikely(error))
break;
file->position(sort_form->record[0]);

13
sql/filesort.h
View File

@ -62,6 +62,13 @@ public:
Filesort_tracker *tracker;
Sort_keys *sort_keys;
/*
TRUE means all the fields of table of whose bitmap read_set is set
need to be read while reading records in the sort buffer.
FALSE otherwise
*/
bool set_all_read_bits;
Filesort(ORDER *order_arg, ha_rows limit_arg, bool sort_positions_arg,
SQL_SELECT *select_arg):
order(order_arg),
@ -71,7 +78,9 @@ public:
own_select(false),
using_pq(false),
sort_positions(sort_positions_arg),
sort_keys(NULL)
sort_keys(NULL),
set_all_read_bits(FALSE),
unpack(NULL)
{
DBUG_ASSERT(order);
};
@ -79,6 +88,8 @@ public:
~Filesort() { cleanup(); }
/* Prepare ORDER BY list for sorting. */
Sort_keys* make_sortorder(THD *thd, JOIN *join, table_map first_table_bit);
/* Unpack temp table columns to base table columns*/
void (*unpack)(TABLE *);
private:
void cleanup();

17
sql/opt_subselect.cc
View File

@ -4285,11 +4285,11 @@ bool setup_sj_materialization_part2(JOIN_TAB *sjm_tab)
sjm_tab->type= JT_ALL;
/* Initialize full scan */
sjm_tab->read_first_record= join_read_record_no_init;
sjm_tab->read_first_record= join_init_read_record;
sjm_tab->read_record.copy_field= sjm->copy_field;
sjm_tab->read_record.copy_field_end= sjm->copy_field +
sjm->sjm_table_cols.elements;
sjm_tab->read_record.read_record_func= rr_sequential_and_unpack;
sjm_tab->read_record.read_record_func= read_record_func_for_rr_and_unpack;
}
sjm_tab->bush_children->end[-1].next_select= end_sj_materialize;
@ -7132,3 +7132,16 @@ exit:
thd->lex->current_select= save_curr_select;
DBUG_RETURN(FALSE);
}
/*
@brief
Check if a table is a SJM Scan table
@retval
TRUE SJM scan table
FALSE Otherwise
*/
bool TABLE_LIST::is_sjm_scan_table()
{
return is_active_sjm() && sj_mat_info->is_sj_scan;
}

29
sql/records.cc
View File

@ -822,3 +822,32 @@ inline void SORT_INFO::unpack_addon_fields(uchar *buff)
field->unpack(field->ptr, buff + addonf->offset, buff_end, 0);
}
}
/*
@brief
Read and unpack next record from a table
@details
The function first reads the next record from the table.
If a success then it unpacks the values to the base table fields.
This is used by SJM scan table to unpack the values of the materialized
table to the base table fields
@retval
0 Record successfully read.
@retval
-1 There is no record to be read anymore.
>0 Error
*/
int read_record_func_for_rr_and_unpack(READ_RECORD *info)
{
int error;
if ((error= info->read_record_func_and_unpack_calls(info)))
return error;
for (Copy_field *cp= info->copy_field; cp != info->copy_field_end; cp++)
(*cp->do_copy)(cp);
return error;
}

1
sql/records.h
View File

@ -55,6 +55,7 @@ struct READ_RECORD
TABLE *table; /* Head-form */
Unlock_row_func unlock_row;
Read_func read_record_func;
Read_func read_record_func_and_unpack_calls;
THD *thd;
SQL_SELECT *select;
uint ref_length, reclength, rec_cache_size, error_offset;

106
sql/sql_select.cc
View File

@ -3858,6 +3858,16 @@ JOIN::add_sorting_to_table(JOIN_TAB *tab, ORDER *order)
tab->select);
if (!tab->filesort)
return true;
TABLE *table= tab->table;
if ((tab == join_tab + const_tables) &&
table->pos_in_table_list &&
table->pos_in_table_list->is_sjm_scan_table())
{
tab->filesort->set_all_read_bits= TRUE;
tab->filesort->unpack= unpack_to_base_table_fields;
}
/*
Select was moved to filesort->select to force join_init_read_record to use
sorted result instead of reading table through select.
@ -14244,37 +14254,8 @@ remove_const(JOIN *join,ORDER *first_order, COND *cond,
can be used without tmp. table.
*/
bool can_subst_to_first_table= false;
bool first_is_in_sjm_nest= false;
if (first_is_base_table)
{
TABLE_LIST *tbl_for_first=
join->join_tab[join->const_tables].table->pos_in_table_list;
first_is_in_sjm_nest= tbl_for_first->sj_mat_info &&
tbl_for_first->sj_mat_info->is_used;
}
/*
Currently we do not employ the optimization that uses multiple
equalities for ORDER BY to remove tmp table in the case when
the first table happens to be the result of materialization of
a semi-join nest ( <=> first_is_in_sjm_nest == true).
When a semi-join nest is materialized and scanned to look for
possible matches in the remaining tables for every its row
the fields from the result of materialization are copied
into the record buffers of tables from the semi-join nest.
So these copies are used to access the remaining tables rather
than the fields from the result of materialization.
Unfortunately now this so-called 'copy back' technique is
supported only if the rows are scanned with the rr_sequential
function, but not with other rr_* functions that are employed
when the result of materialization is required to be sorted.
TODO: either to support 'copy back' technique for the above case,
or to get rid of this technique altogether.
*/
if (optimizer_flag(join->thd, OPTIMIZER_SWITCH_ORDERBY_EQ_PROP) &&
first_is_base_table && !first_is_in_sjm_nest &&
first_is_base_table &&
order->item[0]->real_item()->type() == Item::FIELD_ITEM &&
join->cond_equal)
{
@ -20243,19 +20224,6 @@ do_select(JOIN *join, Procedure *procedure)
}
int rr_sequential_and_unpack(READ_RECORD *info)
{
int error;
if (unlikely((error= rr_sequential(info))))
return error;
for (Copy_field *cp= info->copy_field; cp != info->copy_field_end; cp++)
(*cp->do_copy)(cp);
return error;
}
/**
@brief
Instantiates temporary table
@ -21551,6 +21519,8 @@ bool test_if_use_dynamic_range_scan(JOIN_TAB *join_tab)
int join_init_read_record(JOIN_TAB *tab)
{
bool need_unpacking= FALSE;
JOIN *join= tab->join;
/*
Note: the query plan tree for the below operations is constructed in
save_agg_explain_data.
@ -21558,6 +21528,12 @@ int join_init_read_record(JOIN_TAB *tab)
if (tab->distinct && tab->remove_duplicates()) // Remove duplicates.
return 1;
if (join->top_join_tab_count != join->const_tables)
{
TABLE_LIST *tbl= tab->table->pos_in_table_list;
need_unpacking= tbl ? tbl->is_sjm_scan_table() : FALSE;
}
tab->build_range_rowid_filter_if_needed();
if (tab->filesort && tab->sort_table()) // Sort table.
@ -21565,6 +21541,11 @@ int join_init_read_record(JOIN_TAB *tab)
DBUG_EXECUTE_IF("kill_join_init_read_record",
tab->join->thd->set_killed(KILL_QUERY););
if (!tab->preread_init_done && tab->preread_init())
return 1;
if (tab->select && tab->select->quick && tab->select->quick->reset())
{
/* Ensures error status is propagated back to client */
@ -21575,19 +21556,7 @@ int join_init_read_record(JOIN_TAB *tab)
/* make sure we won't get ER_QUERY_INTERRUPTED from any code below */
DBUG_EXECUTE_IF("kill_join_init_read_record",
tab->join->thd->reset_killed(););
if (!tab->preread_init_done && tab->preread_init())
return 1;
if (init_read_record(&tab->read_record, tab->join->thd, tab->table,
tab->select, tab->filesort_result, 1,1, FALSE))
return 1;
return tab->read_record.read_record();
}
int
join_read_record_no_init(JOIN_TAB *tab)
{
Copy_field *save_copy, *save_copy_end;
/*
@ -21597,12 +21566,19 @@ join_read_record_no_init(JOIN_TAB *tab)
save_copy= tab->read_record.copy_field;
save_copy_end= tab->read_record.copy_field_end;
init_read_record(&tab->read_record, tab->join->thd, tab->table,
tab->select, tab->filesort_result, 1, 1, FALSE);
if (init_read_record(&tab->read_record, tab->join->thd, tab->table,
tab->select, tab->filesort_result, 1, 1, FALSE))
return 1;
tab->read_record.copy_field= save_copy;
tab->read_record.copy_field_end= save_copy_end;
tab->read_record.read_record_func= rr_sequential_and_unpack;
if (need_unpacking)
{
tab->read_record.read_record_func_and_unpack_calls=
tab->read_record.read_record_func;
tab->read_record.read_record_func = read_record_func_for_rr_and_unpack;
}
return tab->read_record.read_record();
}
@ -29426,6 +29402,20 @@ void JOIN::init_join_cache_and_keyread()
}
/*
@brief
Unpack temp table fields to base table fields.
*/
void unpack_to_base_table_fields(TABLE *table)
{
JOIN_TAB *tab= table->reginfo.join_tab;
for (Copy_field *cp= tab->read_record.copy_field;
cp != tab->read_record.copy_field_end; cp++)
(*cp->do_copy)(cp);
}
/**
@} (end of group Query_Optimizer)
*/

4
sql/sql_select.h
View File

@ -223,7 +223,7 @@ typedef enum_nested_loop_state
(*Next_select_func)(JOIN *, struct st_join_table *, bool);
Next_select_func setup_end_select_func(JOIN *join, JOIN_TAB *tab);
int rr_sequential(READ_RECORD *info);
int rr_sequential_and_unpack(READ_RECORD *info);
int read_record_func_for_rr_and_unpack(READ_RECORD *info);
Item *remove_pushed_top_conjuncts(THD *thd, Item *cond);
Item *and_new_conditions_to_optimized_cond(THD *thd, Item *cond,
COND_EQUAL **cond_eq,
@ -2358,7 +2358,6 @@ create_virtual_tmp_table(THD *thd, Field *field)
int test_if_item_cache_changed(List<Cached_item> &list);
int join_init_read_record(JOIN_TAB *tab);
int join_read_record_no_init(JOIN_TAB *tab);
void set_position(JOIN *join,uint idx,JOIN_TAB *table,KEYUSE *key);
inline Item * and_items(THD *thd, Item* cond, Item *item)
{
@ -2416,6 +2415,7 @@ int print_explain_message_line(select_result_sink *result,
void explain_append_mrr_info(QUICK_RANGE_SELECT *quick, String *res);
int append_possible_keys(MEM_ROOT *alloc, String_list &list, TABLE *table,
key_map possible_keys);
void unpack_to_base_table_fields(TABLE *table);
/****************************************************************************
Temporary table support for SQL Runtime

3
sql/sql_sort.h
View File

@ -533,6 +533,7 @@ public:
Addon_fields *addon_fields; // Descriptors for companion fields.
Sort_keys *sort_keys;
bool using_pq;
bool set_all_read_bits;
uchar *unique_buff;
bool not_killable;
@ -553,6 +554,8 @@ public:
}
void init_for_filesort(uint sortlen, TABLE *table,
ha_rows maxrows, bool sort_positions);
void (*unpack)(TABLE *);
/// Enables the packing of addons if possible.
void try_to_pack_addons(ulong max_length_for_sort_data);

1
sql/table.h
View File

@ -2769,6 +2769,7 @@ struct TABLE_LIST
*/
const char *get_table_name() const { return view != NULL ? view_name.str : table_name.str; }
bool is_active_sjm();
bool is_sjm_scan_table();
bool is_jtbm() { return MY_TEST(jtbm_subselect != NULL); }
st_select_lex_unit *get_unit();
st_select_lex *get_single_select();