database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-30 16:24:05 +03:00
Code Activity

Fix bug#13293 Wrongly used index results in endless loop.

Browse Source 
Loose index scan using only second part of multipart index was choosen, which
results in creating wrong keys and endless loop.

get_best_group_min_max() now allows loose index scan for distinct only if used
keyparts forms a prefix of the index.


mysql-test/t/group_min_max.test:
  Test case for bug #13293 Wrongly used index results in endless loop.
mysql-test/r/group_min_max.result:
  Test case for bug #13293 Wrongly used index results in endless loop.
sql/opt_range.cc:
  Fix bug #13293 Wrongly used index results in endless loop.
  get_best_group_min_max() now allows loose index scan for distinct only if used keyparts forms a prefix of the index.
This commit is contained in:
unknown
2005-11-24 19:54:02 +03:00
parent b323bb273e
commit 591fabb390
3 changed files with 33 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
sql/opt_range.cc
View File

@ -7197,6 +7197,7 @@ get_best_group_min_max(PARAM *param, SEL_TREE *tree)
{
select_items_it.rewind();
cur_used_key_parts.clear_all();
uint max_key_part= 0;
while ((item= select_items_it++))
{
item_field= (Item_field*) item; /* (SA5) already checked above. */
@ -7214,7 +7215,19 @@ get_best_group_min_max(PARAM *param, SEL_TREE *tree)
cur_group_prefix_len+= cur_part->store_length;
cur_used_key_parts.set_bit(key_part_nr);
++cur_group_key_parts;
max_key_part= max(max_key_part,key_part_nr);
}
/*
Check that used key parts forms a prefix of the index.
To check this we compare bits in all_parts and cur_parts.
all_parts have all bits set from 0 to (max_key_part-1).
cur_parts have bits set for only used keyparts.
*/
ulonglong all_parts, cur_parts;
all_parts= (1<<max_key_part) - 1;
cur_parts= cur_used_key_parts.to_ulonglong() >> 1;
if (all_parts != cur_parts)
goto next_index;
}
else
DBUG_ASSERT(FALSE);