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MDEV-4240: mariadb 5.3.12 using more memory than MySQL 5.1 for an inefficient query

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- Let index_merge allocate table handlers on quick select's MEM_ROOT,
  not on statement's MEM_ROOT. 
  This is crucial for big "range checked for each record" queries, where 
  index_merge can be created and deleted many times during query exection. 
  We should not make O(#rows) allocations on statement's MEM_ROOT.
This commit is contained in:
Sergey Petrunya
2013-04-01 18:03:14 +04:00
parent 3345e7564d
commit 763af1a8a3
2 changed files with 11 additions and 10 deletions
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15
sql/opt_range.cc
View File

@ -1970,7 +1970,7 @@ int QUICK_ROR_INTERSECT_SELECT::init()
1 error
*/
int QUICK_RANGE_SELECT::init_ror_merged_scan(bool reuse_handler)
int QUICK_RANGE_SELECT::init_ror_merged_scan(bool reuse_handler, MEM_ROOT *alloc)
{
handler *save_file= file, *org_file;
my_bool org_key_read;
@ -1997,7 +1997,7 @@ int QUICK_RANGE_SELECT::init_ror_merged_scan(bool reuse_handler)
}
thd= head->in_use;
if (!(file= head->file->clone(head->s->normalized_path.str, thd->mem_root)))
if (!(file= head->file->clone(head->s->normalized_path.str, alloc)))
{
/*
Manually set the error flag. Note: there seems to be quite a few
@ -2084,7 +2084,8 @@ failure:
0 OK
other error code
*/
int QUICK_ROR_INTERSECT_SELECT::init_ror_merged_scan(bool reuse_handler)
int QUICK_ROR_INTERSECT_SELECT::init_ror_merged_scan(bool reuse_handler,
MEM_ROOT *alloc)
{
List_iterator_fast<QUICK_SELECT_WITH_RECORD> quick_it(quick_selects);
QUICK_SELECT_WITH_RECORD *cur;
@ -2101,14 +2102,14 @@ int QUICK_ROR_INTERSECT_SELECT::init_ror_merged_scan(bool reuse_handler)
There is no use of this->file. Use it for the first of merged range
selects.
*/
if (quick->init_ror_merged_scan(TRUE))
if (quick->init_ror_merged_scan(TRUE, alloc))
DBUG_RETURN(1);
quick->file->extra(HA_EXTRA_KEYREAD_PRESERVE_FIELDS);
}
while ((cur= quick_it++))
{
quick= cur->quick;
if (quick->init_ror_merged_scan(FALSE))
if (quick->init_ror_merged_scan(FALSE, alloc))
DBUG_RETURN(1);
quick->file->extra(HA_EXTRA_KEYREAD_PRESERVE_FIELDS);
/* All merged scans share the same record buffer in intersection. */
@ -2136,7 +2137,7 @@ int QUICK_ROR_INTERSECT_SELECT::init_ror_merged_scan(bool reuse_handler)
int QUICK_ROR_INTERSECT_SELECT::reset()
{
DBUG_ENTER("QUICK_ROR_INTERSECT_SELECT::reset");
if (!scans_inited && init_ror_merged_scan(TRUE))
if (!scans_inited && init_ror_merged_scan(TRUE, &alloc))
DBUG_RETURN(1);
scans_inited= TRUE;
List_iterator_fast<QUICK_SELECT_WITH_RECORD> it(quick_selects);
@ -2268,7 +2269,7 @@ int QUICK_ROR_UNION_SELECT::reset()
List_iterator_fast<QUICK_SELECT_I> it(quick_selects);
while ((quick= it++))
{
if (quick->init_ror_merged_scan(FALSE))
if (quick->init_ror_merged_scan(FALSE, &alloc))
DBUG_RETURN(1);
}
scans_inited= TRUE;

6
sql/opt_range.h
View File

@ -310,7 +310,7 @@ public:
0 Ok
other Error
*/
virtual int init_ror_merged_scan(bool reuse_handler)
virtual int init_ror_merged_scan(bool reuse_handler, MEM_ROOT *alloc)
{ DBUG_ASSERT(0); return 1; }
/*
@ -448,7 +448,7 @@ public:
uchar *cur_prefix);
bool reverse_sorted() { return 0; }
bool unique_key_range();
int init_ror_merged_scan(bool reuse_handler);
int init_ror_merged_scan(bool reuse_handler, MEM_ROOT *alloc);
void save_last_pos()
{ file->position(record); }
int get_type() { return QS_TYPE_RANGE; }
@ -681,7 +681,7 @@ public:
#ifndef DBUG_OFF
void dbug_dump(int indent, bool verbose);
#endif
int init_ror_merged_scan(bool reuse_handler);
int init_ror_merged_scan(bool reuse_handler, MEM_ROOT *alloc);
bool push_quick_back(MEM_ROOT *alloc, QUICK_RANGE_SELECT *quick_sel_range);
class QUICK_SELECT_WITH_RECORD : public Sql_alloc