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Fixed bug mdev-4063 (bug #56927).

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This bug could result in returning 0 for the expressions of the form 
<aggregate_function>(distinct field) when the system variable  
max_heap_table_size was set to a small enough number.
It happened because the method Unique::walk() did not support
the case when more than one pass was needed to merge the trees
of distinct values saved in an external file.

Backported a fix in grant_lowercase.test from mariadb 5.5.
This commit is contained in:
Igor Babaev 2013-01-21 11:47:45 -08:00
parent 2e11ca36f2
commit fade3647ec
6 changed files with 146 additions and 69 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
mysql-test/r/sum_distinct-big.result
View File

@ -103,5 +103,20 @@ sm
10323810
10325070
10326330
#
# Bug mdev-4063: SUM(DISTINCT...) with small'max_heap_table_size
# (bug #56927)
#
SET max_heap_table_size=default;
INSERT INTO t1 SELECT id+16384 FROM t1;
DELETE FROM t2;
INSERT INTO t2 SELECT id FROM t1 ORDER BY id*rand();
SELECT SUM(DISTINCT id) sm FROM t2;
sm
536887296
SET max_heap_table_size=16384;
SELECT SUM(DISTINCT id) sm FROM t2;
sm
536887296
DROP TABLE t1;
DROP TABLE t2;

1
mysql-test/t/grant_lowercase.test
View File

@ -1,4 +1,5 @@
# test cases for strmov(tmp_db, db) -> strnmov replacement in sql_acl.cc
--source include/not_embedded.inc
#
# http://seclists.org/fulldisclosure/2012/Dec/4

17
mysql-test/t/sum_distinct-big.test
View File

@ -63,5 +63,22 @@ SELECT SUM(DISTINCT id) sm FROM t1;
SELECT SUM(DISTINCT id) sm FROM t2;
SELECT SUM(DISTINCT id) sm FROM t1 GROUP BY id % 13;
--echo #
--echo # Bug mdev-4063: SUM(DISTINCT...) with small'max_heap_table_size
--echo # (bug #56927)
--echo #
SET max_heap_table_size=default;
INSERT INTO t1 SELECT id+16384 FROM t1;
DELETE FROM t2;
INSERT INTO t2 SELECT id FROM t1 ORDER BY id*rand();
SELECT SUM(DISTINCT id) sm FROM t2;
SET max_heap_table_size=16384;
SELECT SUM(DISTINCT id) sm FROM t2;
DROP TABLE t1;
DROP TABLE t2;

4
sql/item_sum.cc
View File

@ -1084,7 +1084,7 @@ void Item_sum_distinct::calculate_val_and_count()
if (tree)
{
table->field[0]->set_notnull();
tree->walk(item_sum_distinct_walk, (void*) this);
tree->walk(table, item_sum_distinct_walk, (void*) this);
}
is_evaluated= TRUE;
}
@ -2583,7 +2583,7 @@ longlong Item_sum_count_distinct::val_int()
if (tree->elements == 0)
return (longlong) tree->elements_in_tree(); // everything fits in memory
count= 0;
tree->walk(count_distinct_walk, (void*) &count);
tree->walk(table, count_distinct_walk, (void*) &count);
is_evaluated= TRUE;
return (longlong) count;
}

4
sql/sql_class.h
View File

@ -3008,6 +3008,8 @@ class Unique :public Sql_alloc
bool flush();
uint size;
bool merge(TABLE *table, uchar *buff, bool without_last_merge);
public:
ulong elements;
Unique(qsort_cmp2 comp_func, void *comp_func_fixed_arg,
@ -3035,7 +3037,7 @@ public:
}
void reset();
bool walk(tree_walk_action action, void *walk_action_arg);
bool walk(TABLE *table, tree_walk_action action, void *walk_action_arg);
uint get_size() const { return size; }
ulonglong get_max_in_memory_size() const { return max_in_memory_size; }

174
sql/uniques.cc
View File

@ -538,6 +538,7 @@ end:
SYNOPSIS
Unique:walk()
All params are 'IN':
table parameter for the call of the merge method
action function-visitor, typed in include/my_tree.h
function is called for each unique element
arg argument for visitor, which is passed to it on each call
@ -546,30 +547,117 @@ end:
<> 0 error
*/
bool Unique::walk(tree_walk_action action, void *walk_action_arg)
bool Unique::walk(TABLE *table, tree_walk_action action, void *walk_action_arg)
{
int res;
int res= 0;
uchar *merge_buffer;
if (elements == 0) /* the whole tree is in memory */
return tree_walk(&tree, action, walk_action_arg, left_root_right);
table->sort.found_records=elements+tree.elements_in_tree;
/* flush current tree to the file to have some memory for merge buffer */
if (flush())
return 1;
if (flush_io_cache(&file) || reinit_io_cache(&file, READ_CACHE, 0L, 0, 0))
return 1;
if (!(merge_buffer= (uchar *) my_malloc((ulong) max_in_memory_size, MYF(0))))
ulong buff_sz= (max_in_memory_size / size + 1) * size;
if (!(merge_buffer= (uchar *) my_malloc((ulong) buff_sz, MYF(0))))
return 1;
res= merge_walk(merge_buffer, (ulong) max_in_memory_size, size,
(BUFFPEK *) file_ptrs.buffer,
(BUFFPEK *) file_ptrs.buffer + file_ptrs.elements,
action, walk_action_arg,
tree.compare, tree.custom_arg, &file);
if (buff_sz < (ulong) (size * (file_ptrs.elements + 1)))
res= merge(table, merge_buffer, buff_sz >= size * MERGEBUFF2) ;
if (!res)
{
res= merge_walk(merge_buffer, (ulong) max_in_memory_size, size,
(BUFFPEK *) file_ptrs.buffer,
(BUFFPEK *) file_ptrs.buffer + file_ptrs.elements,
action, walk_action_arg,
tree.compare, tree.custom_arg, &file);
}
my_free((char*) merge_buffer, MYF(0));
return res;
}
/*
DESCRIPTION
Perform multi-pass sort merge of the elements accessed through table->sort,
using the buffer buff as the merge buffer. The last pass is not performed
if without_last_merge is TRUE.
SYNOPSIS
Unique:merge()
All params are 'IN':
table the parameter to access sort context
buff merge buffer
without_last_merge TRUE <=> do not perform the last merge
RETURN VALUE
0 OK
<> 0 error
*/
bool Unique::merge(TABLE *table, uchar *buff, bool without_last_merge)
{
SORTPARAM sort_param;
IO_CACHE *outfile= table->sort.io_cache;
BUFFPEK *file_ptr= (BUFFPEK*) file_ptrs.buffer;
uint maxbuffer= file_ptrs.elements - 1;
my_off_t save_pos;
bool error= 1;
/* Open cached file if it isn't open */
if (!outfile)
outfile= table->sort.io_cache= (IO_CACHE*) my_malloc(sizeof(IO_CACHE),
MYF(MY_ZEROFILL));
if (!outfile ||
(! my_b_inited(outfile) &&
open_cached_file(outfile,mysql_tmpdir,TEMP_PREFIX,READ_RECORD_BUFFER,
MYF(MY_WME))))
return 1;
reinit_io_cache(outfile,WRITE_CACHE,0L,0,0);
bzero((char*) &sort_param,sizeof(sort_param));
sort_param.max_rows= elements;
sort_param.sort_form= table;
sort_param.rec_length= sort_param.sort_length= sort_param.ref_length=
size;
sort_param.keys= (uint) (max_in_memory_size / sort_param.sort_length);
sort_param.not_killable= 1;
sort_param.unique_buff= buff + (sort_param.keys * sort_param.sort_length);
sort_param.compare= (qsort2_cmp) buffpek_compare;
sort_param.cmp_context.key_compare= tree.compare;
sort_param.cmp_context.key_compare_arg= tree.custom_arg;
/* Merge the buffers to one file, removing duplicates */
if (merge_many_buff(&sort_param,buff,file_ptr,&maxbuffer,&file))
goto err;
if (flush_io_cache(&file) ||
reinit_io_cache(&file,READ_CACHE,0L,0,0))
goto err;
if (without_last_merge)
{
file_ptrs.elements= maxbuffer+1;
return 0;
}
if (merge_buffers(&sort_param, &file, outfile, buff, file_ptr,
file_ptr, file_ptr+maxbuffer,0))
goto err;
error= 0;
err:
if (flush_io_cache(outfile))
error= 1;
/* Setup io_cache for reading */
save_pos= outfile->pos_in_file;
if (reinit_io_cache(outfile,READ_CACHE,0L,0,0))
error= 1;
outfile->end_of_file=save_pos;
return error;
}
/*
Modify the TABLE element so that when one calls init_records()
the rows will be read in priority order.
@ -577,8 +665,9 @@ bool Unique::walk(tree_walk_action action, void *walk_action_arg)
bool Unique::get(TABLE *table)
{
SORTPARAM sort_param;
table->sort.found_records=elements+tree.elements_in_tree;
bool rc= 1;
uchar *sort_buffer= NULL;
table->sort.found_records= elements+tree.elements_in_tree;
if (my_b_tell(&file) == 0)
{
@ -594,63 +683,16 @@ bool Unique::get(TABLE *table)
/* Not enough memory; Save the result to file && free memory used by tree */
if (flush())
return 1;
IO_CACHE *outfile=table->sort.io_cache;
BUFFPEK *file_ptr= (BUFFPEK*) file_ptrs.buffer;
uint maxbuffer= file_ptrs.elements - 1;
uchar *sort_buffer;
my_off_t save_pos;
bool error=1;
/* Open cached file if it isn't open */
outfile=table->sort.io_cache=(IO_CACHE*) my_malloc(sizeof(IO_CACHE),
MYF(MY_ZEROFILL));
if (!outfile ||
(! my_b_inited(outfile) &&
open_cached_file(outfile,mysql_tmpdir,TEMP_PREFIX,READ_RECORD_BUFFER,
MYF(MY_WME))))
ulong buff_sz= (max_in_memory_size / size + 1) * size;
if (!(sort_buffer= (uchar*) my_malloc(buff_sz, MYF(0))))
return 1;
reinit_io_cache(outfile,WRITE_CACHE,0L,0,0);
bzero((char*) &sort_param,sizeof(sort_param));
sort_param.max_rows= elements;
sort_param.sort_form=table;
sort_param.rec_length= sort_param.sort_length= sort_param.ref_length=
size;
sort_param.keys= (uint) (max_in_memory_size / sort_param.sort_length);
sort_param.not_killable=1;
if (merge(table, sort_buffer, FALSE))
goto err;
rc= 0;
if (!(sort_buffer=(uchar*) my_malloc((sort_param.keys+1) *
sort_param.sort_length,
MYF(0))))
return 1;
sort_param.unique_buff= sort_buffer+(sort_param.keys*
sort_param.sort_length);
sort_param.compare= (qsort2_cmp) buffpek_compare;
sort_param.cmp_context.key_compare= tree.compare;
sort_param.cmp_context.key_compare_arg= tree.custom_arg;
/* Merge the buffers to one file, removing duplicates */
if (merge_many_buff(&sort_param,sort_buffer,file_ptr,&maxbuffer,&file))
goto err;
if (flush_io_cache(&file) ||
reinit_io_cache(&file,READ_CACHE,0L,0,0))
goto err;
if (merge_buffers(&sort_param, &file, outfile, sort_buffer, file_ptr,
file_ptr, file_ptr+maxbuffer,0))
goto err;
error=0;
err:
x_free(sort_buffer);
if (flush_io_cache(outfile))
error=1;
/* Setup io_cache for reading */
save_pos=outfile->pos_in_file;
if (reinit_io_cache(outfile,READ_CACHE,0L,0,0))
error=1;
outfile->end_of_file=save_pos;
return error;
err:
x_free(sort_buffer);
return rc;
}