database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-29 05:21:33 +03:00
Code Activity

MDEV-31893 Valgrind reports issues in main.join_cache_notasan

Browse Source 
This is also related to
MDEV-31348 Assertion `last_key_entry >= end_pos' failed in virtual bool
           JOIN_CACHE_HASHED::put_record()

Valgrind exposed a problem with the join_cache for hash joins:
=25636== Conditional jump or move depends on uninitialised value(s)
==25636== at 0xA8FF4E: JOIN_CACHE_HASHED::init_hash_table()
          (sql_join_cache.cc:2901)

The reason for this was that avg_record_length contained a random value
if one had used SET optimizer_switch='optimize_join_buffer_size=off'.

This causes either 'random size' memory to be allocated (up to
join_buffer_size) which can increase memory usage or, if avg_record_length
is less than the row size, memory overwrites in thd->mem_root, which is
bad.

Fixed by setting avg_record_length in JOIN_CACHE_HASHED::init()
before it's used.

There is no test case for MDEV-31893 as valgrind of join_cache_notasan
checks that.
I added a test case for MDEV-31348.
This commit is contained in:
Monty
2023-08-10 16:13:32 +03:00
committed by Oleksandr Byelkin
parent 0ede90dd31
commit 2aea938749
6 changed files with 70 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

29
sql/sql_join_cache.cc
View File

@ -800,6 +800,18 @@ size_t JOIN_CACHE::get_min_join_buffer_size()
}
size_t JOIN_CACHE::calc_avg_record_length()
{
size_t len= 0;
for (JOIN_TAB *tab= start_tab; tab != join_tab;
tab= next_linear_tab(join, tab, WITHOUT_BUSH_ROOTS))
{
len+= tab->get_used_fieldlength();
}
len+= get_record_max_affix_length();
return len;
}
/*
Get the maximum possible size of the cache join buffer
@ -822,9 +834,9 @@ size_t JOIN_CACHE::get_min_join_buffer_size()
'max_buff_size' in order to use it directly at the next
invocations of the function.
RETURN VALUE
The maximum possible size of the join buffer of this cache
The maximum possible size of the join buffer of this cache
avg_record_length is also updated if optimize_buff_size != 0
*/
size_t JOIN_CACHE::get_max_join_buffer_size(bool optimize_buff_size,
@ -839,19 +851,13 @@ size_t JOIN_CACHE::get_max_join_buffer_size(bool optimize_buff_size,
return max_buff_size= limit_sz;
size_t max_sz;
size_t len= 0;
size_t len;
double max_records, partial_join_cardinality=
(join_tab-1)->get_partial_join_cardinality();
/* Expected join buffer space used for one record */
size_t space_per_record;
for (JOIN_TAB *tab= start_tab; tab != join_tab;
tab= next_linear_tab(join, tab, WITHOUT_BUSH_ROOTS))
{
len+= tab->get_used_fieldlength();
}
len+= get_record_max_affix_length();
avg_record_length= len;
len= avg_record_length= calc_avg_record_length();
len+= get_max_key_addon_space_per_record() + avg_aux_buffer_incr;
space_per_record= len;
@ -2786,7 +2792,6 @@ bool JOIN_CACHE_BKAH::save_explain_data(EXPLAIN_BKA_TYPE *explain)
int JOIN_CACHE_HASHED::init(bool for_explain)
{
TABLE_REF *ref= &join_tab->ref;
DBUG_ENTER("JOIN_CACHE_HASHED::init");
hash_table= 0;
@ -2873,6 +2878,8 @@ int JOIN_CACHE_HASHED::init_hash_table()
hash_table= 0;
key_entries= 0;
avg_record_length= calc_avg_record_length();
/* Calculate the minimal possible value of size_of_key_ofs greater than 1 */
uint max_size_of_key_ofs= MY_MAX(2, get_size_of_rec_offset());
for (size_of_key_ofs= 2;