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Commit ade0f40f authored by Varun Gupta's avatar Varun Gupta
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MDEV-22819: Wrong result or Assertion `ix > 0' failed in read_to_buffer upon... 

MDEV-22819: Wrong result or Assertion `ix > 0' failed in read_to_buffer upon select with GROUP BY and GROUP_CONCAT

In the merge_buffers phase for sorting, the sort buffer size is divided between the number of chunks.
The chunks have a start and end position (m_buffer_start and m_buffer_end).
Then we read the as many records that fit in this buffer for a chunk of the file.
The issue here was we were resetting the end of buffer(m_buffer_end) to the number of bytes that was
read, this was causing a problem because with dynamic size of sort keys it is possible that later
we would not be able to accommodate even one key inside a chunk of file.
So the fix was to not reset the end of buffer for a chunk of file.
parent ba2c2cfb
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Showing with 106 additions and 6 deletions
mysql-test/main/order_by.result
View file @ ade0f40f
......@@ -3965,4 +3965,62 @@ a
1
0
DROP TABLE t1;
#
# MDEV-22819:Wrong result or Assertion `ix > 0' failed in read_to_buffer upon select
# with GROUP BY and GROUP_CONCAT
#
CREATE TABLE t1 (a VARCHAR(1000), b CHAR(1));
INSERT INTO t1 VALUES
(REPEAT('a',1000),'a'),(REPEAT('t',932),'t'),('x',NULL),('x',NULL),
(REPEAT('z',298),'z'),(REPEAT('p',1000),'p'),(REPEAT('k',468),'k'),
(REPEAT('c',1000),'c'),(REPEAT('o',648),'o'),('x',NULL),('x',NULL),
(REPEAT('c',258),'c'),(REPEAT('t',414),'t'),(REPEAT('f',966),'f'),
(REPEAT('y',746),'y'),(REPEAT('f',1000),'f');
INSERT INTO t1 SELECT * FROM t1;
INSERT INTO t1 SELECT * FROM t1;
INSERT INTO t1 SELECT * FROM t1;
INSERT INTO t1 SELECT * FROM t1;
SET @save_sort_buffer_size= @@sort_buffer_size;
SET sort_buffer_size= 16384;
SELECT LEFT(a,1), GROUP_CONCAT(b) FROM t1 GROUP BY a;
LEFT(a,1) GROUP_CONCAT(b)
a a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a
c c,c,c,c,c,c,c,c,c,c,c,c,c,c,c,c
c c,c,c,c,c,c,c,c,c,c,c,c,c,c,c,c
f f,f,f,f,f,f,f,f,f,f,f,f,f,f,f,f
f f,f,f,f,f,f,f,f,f,f,f,f,f,f,f,f
k k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k
o o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o
p p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p
t t,t,t,t,t,t,t,t,t,t,t,t,t,t,t,t
t t,t,t,t,t,t,t,t,t,t,t,t,t,t,t,t
x NULL
y y,y,y,y,y,y,y,y,y,y,y,y,y,y,y,y
z z,z,z,z,z,z,z,z,z,z,z,z,z,z,z,z
SELECT SUBSTR(a,1,1), LENGTH(a), GROUP_CONCAT(b), COUNT(*) FROM t1 GROUP BY a;
SUBSTR(a,1,1) LENGTH(a) GROUP_CONCAT(b) COUNT(*)
a 1000 a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a 16
c 258 c,c,c,c,c,c,c,c,c,c,c,c,c,c,c,c 16
c 1000 c,c,c,c,c,c,c,c,c,c,c,c,c,c,c,c 16
f 966 f,f,f,f,f,f,f,f,f,f,f,f,f,f,f,f 16
f 1000 f,f,f,f,f,f,f,f,f,f,f,f,f,f,f,f 16
k 468 k,k,k,k,k,k,k,k,k,k,k,k,k,k,k,k 16
o 648 o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o 16
p 1000 p,p,p,p,p,p,p,p,p,p,p,p,p,p,p,p 16
t 414 t,t,t,t,t,t,t,t,t,t,t,t,t,t,t,t 16
t 932 t,t,t,t,t,t,t,t,t,t,t,t,t,t,t,t 16
x 1 NULL 64
y 746 y,y,y,y,y,y,y,y,y,y,y,y,y,y,y,y 16
z 298 z,z,z,z,z,z,z,z,z,z,z,z,z,z,z,z 16
SET @@sort_buffer_size= @save_sort_buffer_size;
DROP TABLE t1;
CREATE TABLE t1(a VARCHAR(1027), b INT);
INSERT INTO t1 SELECT seq, seq from seq_1_to_34;
SET @save_tmp_memory_table_size= @@tmp_memory_table_size;
SET tmp_memory_table_size= 1056*2;
SELECT COUNT(DISTINCT a) FROM t1;
COUNT(DISTINCT a)
34
SET @@tmp_memory_table_size= @save_tmp_memory_table_size;
DROP TABLE t1;
# End of 10.5 tests
mysql-test/main/order_by.test
View file @ ade0f40f
......@@ -2465,4 +2465,40 @@ SELECT * FROM t1 ORDER BY CONVERT(AES_ENCRYPT(1,a), CHAR(4));
--enable_warnings
DROP TABLE t1;
--echo #
--echo # MDEV-22819:Wrong result or Assertion `ix > 0' failed in read_to_buffer upon select
--echo # with GROUP BY and GROUP_CONCAT
--echo #
CREATE TABLE t1 (a VARCHAR(1000), b CHAR(1));
INSERT INTO t1 VALUES
(REPEAT('a',1000),'a'),(REPEAT('t',932),'t'),('x',NULL),('x',NULL),
(REPEAT('z',298),'z'),(REPEAT('p',1000),'p'),(REPEAT('k',468),'k'),
(REPEAT('c',1000),'c'),(REPEAT('o',648),'o'),('x',NULL),('x',NULL),
(REPEAT('c',258),'c'),(REPEAT('t',414),'t'),(REPEAT('f',966),'f'),
(REPEAT('y',746),'y'),(REPEAT('f',1000),'f');
INSERT INTO t1 SELECT * FROM t1;
INSERT INTO t1 SELECT * FROM t1;
INSERT INTO t1 SELECT * FROM t1;
INSERT INTO t1 SELECT * FROM t1;
SET @save_sort_buffer_size= @@sort_buffer_size;
SET sort_buffer_size= 16384;
SELECT LEFT(a,1), GROUP_CONCAT(b) FROM t1 GROUP BY a;
SELECT SUBSTR(a,1,1), LENGTH(a), GROUP_CONCAT(b), COUNT(*) FROM t1 GROUP BY a;
SET @@sort_buffer_size= @save_sort_buffer_size;
DROP TABLE t1;
CREATE TABLE t1(a VARCHAR(1027), b INT);
INSERT INTO t1 SELECT seq, seq from seq_1_to_34;
SET @save_tmp_memory_table_size= @@tmp_memory_table_size;
SET tmp_memory_table_size= 1056*2;
SELECT COUNT(DISTINCT a) FROM t1;
SET @@tmp_memory_table_size= @save_tmp_memory_table_size;
DROP TABLE t1;
--echo # End of 10.5 tests
sql/filesort.cc
View file @ ade0f40f
......@@ -1845,17 +1845,15 @@ bool merge_buffers(Sort_param *param, IO_CACHE *from_file,
offsetof(Merge_chunk,m_current_key), 0,
(queue_compare) cmp, first_cmp_arg, 0, 0)))
DBUG_RETURN(1); /* purecov: inspected */
const size_t chunk_sz = (sort_buffer.size()/((uint) (Tb-Fb) +1));
for (buffpek= Fb ; buffpek <= Tb ; buffpek++)
{
buffpek->set_buffer(strpos,
strpos + (sort_buffer.size()/((uint) (Tb-Fb) +1)));
buffpek->set_buffer(strpos, strpos + chunk_sz);
buffpek->set_max_keys(maxcount);
bytes_read= read_to_buffer(from_file, buffpek, param, packed_format);
if (unlikely(bytes_read == (ulong) -1))
goto err; /* purecov: inspected */
strpos+= bytes_read;
buffpek->set_buffer_end(strpos);
strpos+= chunk_sz;
// If less data in buffers than expected
buffpek->set_max_keys(buffpek->mem_count());
queue_insert(&queue, (uchar*) buffpek);
......
sql/uniques.cc
View file @ ade0f40f
......@@ -735,6 +735,13 @@ bool Unique::merge(TABLE *table, uchar *buff, size_t buff_size,
sort_param.cmp_context.key_compare= tree.compare;
sort_param.cmp_context.key_compare_arg= tree.custom_arg;
/*
We need to remove the size allocated for the unique buffer.
The sort_buffer_size is:
MY_MAX(MERGEBUFF2+1, max_in_memory_size/full_size+1) * full_size;
*/
buff_size-= full_size;
/* Merge the buffers to one file, removing duplicates */
if (merge_many_buff(&sort_param,
Bounds_checked_array<uchar>(buff, buff_size),
......@@ -802,7 +809,8 @@ bool Unique::get(TABLE *table)
/* Not enough memory; Save the result to file && free memory used by tree */
if (flush())
DBUG_RETURN(1);
size_t buff_sz= (max_in_memory_size / full_size + 1) * full_size;
size_t buff_sz= MY_MAX(MERGEBUFF2+1, max_in_memory_size/full_size+1) * full_size;
if (!(sort_buffer= (uchar*) my_malloc(key_memory_Unique_sort_buffer, buff_sz,
MYF(MY_THREAD_SPECIFIC|MY_WME))))
DBUG_RETURN(1);
......
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