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MDEV-13458: Wrong result for aggregate function with distinct clause when the value for tmp_table_size is small

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Fixed by making sure that the sort buffer would have atleast MERGEBUFF2 keys.
Also fixed MDEV-13457 by making sure that an empty tree is never dumped to the disk
This commit is contained in:
Varun Gupta 2017-08-08 21:13:45 +05:30
parent c8a0244e95
commit 0739179857
4 changed files with 63 additions and 5 deletions
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25
mysql-test/r/count_distinct.result
View File

@ -106,3 +106,28 @@ count(distinct user_id)
17
drop table t1;
set @@tmp_table_size = default;
create table t1 (
a VARCHAR(1020),
b int
);
insert into t1 values
( 0 , 1 ),
( 1 , 2 ),
( 2 , 3 ),
( 3 , 4 ),
( 4 , 5 ),
( 5 , 6 ),
( 6 , 7 ),
( 7 , 8 ),
( 8 , 9 ),
( 9 , 10 ),
( 0 , 11 ),
( 1 , 12 ),
( 2 , 13 ),
( 3 , 14 );
set @@tmp_table_size=1024;
select count(distinct a) from t1;
count(distinct a)
10
drop table t1;
set @@tmp_table_size = default;

29
mysql-test/t/count_distinct.test
View File

@ -120,6 +120,35 @@ select count(distinct user_id) from t1;
drop table t1;
set @@tmp_table_size = default;
#
# MDEV-13457: Wrong result for aggregate function with distinct clause when the value for
# tmp_table_size is small
#
create table t1 (
a VARCHAR(1020),
b int
);
insert into t1 values
( 0 , 1 ),
( 1 , 2 ),
( 2 , 3 ),
( 3 , 4 ),
( 4 , 5 ),
( 5 , 6 ),
( 6 , 7 ),
( 7 , 8 ),
( 8 , 9 ),
( 9 , 10 ),
( 0 , 11 ),
( 1 , 12 ),
( 2 , 13 ),
( 3 , 14 );
set @@tmp_table_size=1024;
select count(distinct a) from t1;
drop table t1;
set @@tmp_table_size = default;
#
# End of 5.5 tests
#

2
sql/sql_class.h
View File

@ -3919,7 +3919,7 @@ public:
{
DBUG_ENTER("unique_add");
DBUG_PRINT("info", ("tree %u - %lu", tree.elements_in_tree, max_elements));
if (!(tree.flag & TREE_ONLY_DUPS) &&
if (!(tree.flag & TREE_ONLY_DUPS) &&
tree.elements_in_tree >= max_elements && flush())
DBUG_RETURN(1);
DBUG_RETURN(!tree_insert(&tree, ptr, 0, tree.custom_arg));

12
sql/uniques.cc
View File

@ -96,6 +96,9 @@ Unique::Unique(qsort_cmp2 comp_func, void * comp_func_fixed_arg,
*/
max_elements= (ulong) (max_in_memory_size /
ALIGN_SIZE(sizeof(TREE_ELEMENT)+size));
if (!max_elements)
max_elements= 1;
(void) open_cached_file(&file, mysql_tmpdir,TEMP_PREFIX, DISK_BUFFER_SIZE,
MYF(MY_WME));
}
@ -608,10 +611,11 @@ bool Unique::walk(TABLE *table, tree_walk_action action, void *walk_action_arg)
if (flush_io_cache(&file) || reinit_io_cache(&file, READ_CACHE, 0L, 0, 0))
return 1;
/*
merge_buffer must fit at least MERGEBUFF2 keys, because
merge_index() can merge that many BUFFPEKs at once.
merge_buffer must fit at least MERGEBUFF2 + 1 keys, because
merge_index() can merge that many BUFFPEKs at once. The extra space for one key
is needed when a piece of merge buffer is re-read, see merge_walk()
*/
size_t buff_sz= max(MERGEBUFF2, max_in_memory_size/full_size+1) * full_size;
size_t buff_sz= max(MERGEBUFF2+1, max_in_memory_size/full_size+1) * full_size;
if (!(merge_buffer = (uchar *)my_malloc(buff_sz, MYF(MY_WME))))
return 1;
if (buff_sz < (ulong) (full_size * (file_ptrs.elements + 1)))
@ -673,7 +677,7 @@ bool Unique::merge(TABLE *table, uchar *buff, bool without_last_merge)
full_size;
sort_param.min_dupl_count= min_dupl_count;
sort_param.res_length= 0;
sort_param.keys= (uint) (max_in_memory_size / sort_param.sort_length);
sort_param.keys= (uint) max((max_in_memory_size / sort_param.sort_length), MERGEBUFF2);
sort_param.not_killable= 1;
sort_param.unique_buff= buff + (sort_param.keys * sort_param.sort_length);