1berry/MariaDB-server
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Fix for bug#5138 continued: added comments, removed extra debug printf calls, changed ha_heap::records_in_range to use table->rec_per_key.

Browse Source
This commit is contained in:
sergefp@mysql.com 2004-10-12 18:21:25 +04:00
parent 2c9d2cf671
commit a0ba02d740
7 changed files with 209 additions and 60 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

49
heap/hp_block.c
View File

@ -18,12 +18,19 @@
#include "heapdef.h"
/* Find record according to record-position */
/*
Find record according to record-position.
The record is located by factoring position number pos into (p_0, p_1, ...)
such that
pos = SUM_i(block->level_info[i].records_under_level * p_i)
{p_0, p_1, ...} serve as indexes to descend the blocks tree.
*/
byte *hp_find_block(HP_BLOCK *block, ulong pos)
{
reg1 int i;
reg3 HP_PTRS *ptr;
reg3 HP_PTRS *ptr; /* block base ptr */
for (i=block->levels-1, ptr=block->root ; i > 0 ; i--)
{
@ -34,8 +41,18 @@ byte *hp_find_block(HP_BLOCK *block, ulong pos)
}
/* get one new block-of-records. Alloc ptr to block if neaded */
/* Interrupts are stopped to allow ha_panic in interrupts */
/*
Get one new block-of-records. Alloc ptr to block if needed
SYNOPSIS
hp_get_new_block()
block HP_BLOCK tree-like block
alloc_length OUT Amount of memory allocated from the heap
Interrupts are stopped to allow ha_panic in interrupts
RETURN
0 OK
1 Out of memory
*/
int hp_get_new_block(HP_BLOCK *block, ulong *alloc_length)
{
@ -46,6 +63,18 @@ int hp_get_new_block(HP_BLOCK *block, ulong *alloc_length)
if (block->level_info[i].free_ptrs_in_block)
break;
/*
Allocate space for leaf block plus space for upper level blocks up to
first level that has a free slot to put the pointer.
In some cases we actually allocate more then we need:
Consider e.g. a situation where we have one level 1 block and one level 0
block, the level 0 block is full and this function is called. We only
need a leaf block in this case. Nevertheless, we will get here with i=1
and will also allocate sizeof(HP_PTRS) for non-leaf block and will never
use this space.
This doesn't add much overhead - with current values of sizeof(HP_PTRS)
and my_default_record_cache_size we get about 1/128 unused memory.
*/
*alloc_length=sizeof(HP_PTRS)*i+block->records_in_block* block->recbuffer;
if (!(root=(HP_PTRS*) my_malloc(*alloc_length,MYF(0))))
return 1;
@ -60,21 +89,33 @@ int hp_get_new_block(HP_BLOCK *block, ulong *alloc_length)
dont_break(); /* Dont allow SIGHUP or SIGINT */
if ((uint) i == block->levels)
{
/* Adding a new level on top of the existing ones. */
block->levels=i+1;
/*
Use first allocated HP_PTRS as a top-level block. Put the current
block tree into the first slot of a new top-level block.
*/
block->level_info[i].free_ptrs_in_block=HP_PTRS_IN_NOD-1;
((HP_PTRS**) root)[0]= block->root;
block->root=block->level_info[i].last_blocks= root++;
}
/* Occupy the free slot we've found at level i */
block->level_info[i].last_blocks->
blocks[HP_PTRS_IN_NOD - block->level_info[i].free_ptrs_in_block--]=
(byte*) root;
/* Add a block subtree with each node having one left-most child */
for (j=i-1 ; j >0 ; j--)
{
block->level_info[j].last_blocks= root++;
block->level_info[j].last_blocks->blocks[0]=(byte*) root;
block->level_info[j].free_ptrs_in_block=HP_PTRS_IN_NOD-1;
}
/*
root now points to last (block->records_in_block* block->recbuffer)
allocated bytes. Use it as a leaf block.
*/
block->level_info[0].last_blocks= root;
allow_break(); /* Allow SIGHUP & SIGINT */
}

4
heap/hp_delete.c
View File

@ -97,8 +97,8 @@ int hp_rb_delete_key(HP_INFO *info, register HP_KEYDEF *keyinfo,
flag Is set if we want's to correct info->current_ptr
RETURN
0 ok
# error number
0 Ok
other Error code
*/
int hp_delete_key(HP_INFO *info, register HP_KEYDEF *keyinfo,

95
heap/hp_write.c
View File

@ -36,7 +36,6 @@ int heap_write(HP_INFO *info, const byte *record)
byte *pos;
HP_SHARE *share=info->s;
DBUG_ENTER("heap_write");
printf("heap_write\n");
#ifndef DBUG_OFF
if (info->mode & O_RDONLY)
{
@ -160,7 +159,31 @@ static byte *next_free_record_pos(HP_SHARE *info)
block_pos*info->block.recbuffer);
}
/* Write a hash-key to the hash-index */
/*
Write a hash-key to the hash-index
SYNOPSIS
info Heap table info
keyinfo Key info
record Table record to added
recpos Memory buffer where the table record will be stored if added
successfully
NOTE
Hash index uses HP_BLOCK structure as a 'growable array' of HASH_INFO
structs. Array size == number of entries in hash index.
hp_mask(hp_rec_hashnr()) maps hash entries values to hash array positions.
If there are several hash entries with the same hash array position P,
they are connected in a linked list via HASH_INFO::next_key. The first
list element is located at position P, next elements are located at
positions for which there is no record that should be located at that
position. The order of elements in the list is arbitrary.
RETURN
0 - OK
-1 - Out of memory
HA_ERR_FOUND_DUPP_KEY - Duplicate record on unique key. The record was
still added and the caller must call hp_delete_key for it.
*/
int hp_write_key(HP_INFO *info, HP_KEYDEF *keyinfo,
const byte *record, byte *recpos)
@ -182,33 +205,52 @@ int hp_write_key(HP_INFO *info, HP_KEYDEF *keyinfo,
pos= hp_find_hash(&keyinfo->block,(first_index=share->records-halfbuff));
/*
We're about to add one more hash position, with hash_mask=#records.
Entries that should be relocated to that position are currently members
of the list that starts at #first_index position.
At #first_index position there may be either:
a) A list of items with hash_mask=first_index. The list contains
1) entries that should be relocated to the list that starts at new
position we're adding
2) entries that should be left in the list starting at #first_index
position
We're about to add one more hash array position, with hash_mask=#records.
The number of hash positions will change and some entries might need to
be relocated to the newly added position. Those entries are currently
members of the list that starts at #first_index position (this is
guaranteed by properties of hp_mask(hp_rec_hashnr(X)) mapping function)
At #first_index position currently there may be either:
a) An entry with hashnr != first_index. We don't need to move it.
or
b) An entry with hashnr != first_index. We don't need to move it.
b) A list of items with hash_mask=first_index. The list contains entries
of 2 types:
1) entries that should be relocated to the list that starts at new
position we're adding ('uppper' list)
2) entries that should be left in the list starting at #first_index
position ('lower' list)
*/
if (pos != empty) /* If some records */
{
do
{
hashnr = hp_rec_hashnr(keyinfo, pos->ptr_to_rec);
if (flag == 0) /* First loop; Check if ok */
if (flag == 0)
{
/* Bail out if we're dealing with case b) from above comment */
/*
First loop, bail out if we're dealing with case a) from above
comment
*/
if (hp_mask(hashnr, share->blength, share->records) != first_index)
break;
}
/*
flag & LOWFIND - found a record that should be put into lower position
flag & LOWUSED - lower position occupied by the record
Same for HIGHFIND and HIGHUSED and 'upper' position
gpos - ptr to last element in lower position's list
gpos2 - ptr to last element in upper position's list
ptr_to_rec - ptr to last entry that should go into lower list.
ptr_to_rec2 - same for upper list.
*/
if (!(hashnr & halfbuff))
{ /* Key will not move */
{
/* Key should be put into 'lower' list */
if (!(flag & LOWFIND))
{
/* key is the first element to go into lower position */
if (flag & HIGHFIND)
{
flag=LOWFIND | HIGHFIND;
@ -219,16 +261,21 @@ int hp_write_key(HP_INFO *info, HP_KEYDEF *keyinfo,
}
else
{
flag=LOWFIND | LOWUSED; /* key isn't changed */
/*
We can only get here at first iteration: key is at 'lower'
position pos and should be left here.
*/
flag=LOWFIND | LOWUSED;
gpos=pos;
ptr_to_rec=pos->ptr_to_rec;
}
}
else
{
/* Already have another key for lower position */
if (!(flag & LOWUSED))
{
/* Change link of previous LOW-key */
/* Change link of previous lower-list key */
gpos->ptr_to_rec=ptr_to_rec;
gpos->next_key=pos;
flag= (flag & HIGHFIND) | (LOWFIND | LOWUSED);
@ -238,19 +285,21 @@ int hp_write_key(HP_INFO *info, HP_KEYDEF *keyinfo,
}
}
else
{ /* key will be moved */
{
/* key will be put into 'higher' list */
if (!(flag & HIGHFIND))
{
flag= (flag & LOWFIND) | HIGHFIND;
/* key shall be moved to the last (empty) position */
gpos2 = empty; empty=pos;
gpos2= empty;
empty= pos;
ptr_to_rec2=pos->ptr_to_rec;
}
else
{
if (!(flag & HIGHUSED))
{
/* Change link of previous hash-key and save */
/* Change link of previous upper-list key and save */
gpos2->ptr_to_rec=ptr_to_rec2;
gpos2->next_key=pos;
flag= (flag & LOWFIND) | (HIGHFIND | HIGHUSED);
@ -263,7 +312,13 @@ int hp_write_key(HP_INFO *info, HP_KEYDEF *keyinfo,
while ((pos=pos->next_key));
if ((flag & (LOWFIND | HIGHFIND)) == (LOWFIND | HIGHFIND))
{
/*
If both 'higher' and 'lower' list have at least one element, now
there are two hash buckets instead of one.
*/
keyinfo->hash_buckets++;
}
if ((flag & (LOWFIND | LOWUSED)) == LOWFIND)
{

44
include/heap.h
View File

@ -63,18 +63,48 @@ typedef struct st_heap_ptrs
struct st_level_info
{
uint free_ptrs_in_block,records_under_level;
HP_PTRS *last_blocks; /* pointers to HP_PTRS or records */
/* Number of unused slots in *last_blocks HP_PTRS block (0 for 0th level) */
uint free_ptrs_in_block;
/*
Maximum number of records that can be 'contained' inside of each element
of last_blocks array. For level 0 - 1, for level 1 - HP_PTRS_IN_NOD, for
level 2 - HP_PTRS_IN_NOD^2 and so forth.
*/
uint records_under_level;
/*
Ptr to last allocated HP_PTRS (or records buffer for level 0) on this
level.
*/
HP_PTRS *last_blocks;
};
typedef struct st_heap_block /* The data is saved in blocks */
/*
Heap table records and hash index entries are stored in HP_BLOCKs.
HP_BLOCK is used as a 'growable array' of fixed-size records. Size of record
is recbuffer bytes.
The internal representation is as follows:
HP_BLOCK is a hierarchical structure of 'blocks'.
A block at level 0 is an array records_in_block records.
A block at higher level is an HP_PTRS structure with pointers to blocks at
lower levels.
At the highest level there is one top block. It is stored in HP_BLOCK::root.
See hp_find_block for a description of how record pointer is obtained from
its index.
See hp_get_new_block
*/
typedef struct st_heap_block
{
HP_PTRS *root;
HP_PTRS *root; /* Top-level block */
struct st_level_info level_info[HP_MAX_LEVELS+1];
uint levels;
uint records_in_block; /* Records in a heap-block */
uint levels; /* number of used levels */
uint records_in_block; /* Records in one heap-block */
uint recbuffer; /* Length of one saved record */
ulong last_allocated; /* Blocks allocated, used by keys */
ulong last_allocated; /* number of records there is allocated space for */
} HP_BLOCK;
struct st_heap_info; /* For referense */

34
mysql-test/r/heap_hash.result
View File

@ -233,6 +233,19 @@ id select_type table type possible_keys key key_len ref rows Extra
insert into t1 select * from t1;
explain select * from t1 where a='aaaa';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 8 const 1 Using where
explain select * from t1 where a='aaab';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 8 const 1 Using where
explain select * from t1 where a='aaac';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 8 const 1 Using where
explain select * from t1 where a='aaad';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 8 const 1 Using where
flush tables;
explain select * from t1 where a='aaaa';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 8 const 2 Using where
explain select * from t1 where a='aaab';
id select_type table type possible_keys key key_len ref rows Extra
@ -248,16 +261,16 @@ delete from t1;
insert into t1 select * from t2;
explain select * from t1 where a='aaaa';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 8 const 2 Using where
1 SIMPLE t1 ref a a 8 const 1 Using where
explain select * from t1 where a='aaab';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 8 const 2 Using where
1 SIMPLE t1 ref a a 8 const 1 Using where
explain select * from t1 where a='aaac';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 8 const 2 Using where
1 SIMPLE t1 ref a a 8 const 1 Using where
explain select * from t1 where a='aaad';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 8 const 2 Using where
1 SIMPLE t1 ref a a 8 const 1 Using where
drop table t1, t2;
create table t1 (
id int unsigned not null primary key auto_increment,
@ -305,6 +318,7 @@ insert into t1 (name) select name from t2;
insert into t1 (name) select name from t2;
insert into t1 (name) select name from t2;
insert into t1 (name) select name from t2;
flush tables;
select count(*) from t1 where name='Matt';
count(*)
7
@ -314,9 +328,8 @@ id select_type table type possible_keys key key_len ref rows Extra
show index from t1;
Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment
t1 0 PRIMARY 1 id NULL 91 NULL NULL HASH
t1 1 heap_idx 1 name NULL 15 NULL NULL HASH
t1 1 heap_idx 1 name NULL 13 NULL NULL HASH
t1 1 btree_idx 1 name A NULL NULL NULL BTREE
flush tables;
show index from t1;
Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment
t1 0 PRIMARY 1 id NULL 91 NULL NULL HASH
@ -333,9 +346,12 @@ show index from t3;
Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment
t3 1 a 1 a NULL NULL NULL NULL HASH
t3 1 a 2 b NULL 15 NULL NULL HASH
flush tables;
show index from t3;
Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment
t3 1 a 1 a NULL NULL NULL NULL HASH
t3 1 a 2 b NULL 13 NULL NULL HASH
drop table t1,t2;
t3 1 a 2 b NULL 15 NULL NULL HASH
explain select * from t1 ignore key(btree_idx), t3 where t1.name='matt' and t3.a = concat('',t1.name) and t3.b=t1.name;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref heap_idx heap_idx 20 const 7 Using where
1 SIMPLE t3 ref a a 40 func,const 6 Using where
drop table t1, t2, t3;

18
mysql-test/t/heap_hash.test
View File

@ -168,6 +168,14 @@ explain select * from t1 where a='aaab';
explain select * from t1 where a='aaac';
explain select * from t1 where a='aaad';
insert into t1 select * from t1;
explain select * from t1 where a='aaaa';
explain select * from t1 where a='aaab';
explain select * from t1 where a='aaac';
explain select * from t1 where a='aaad';
# a known effect: table reload causes statistics to be updated:
flush tables;
explain select * from t1 where a='aaaa';
explain select * from t1 where a='aaab';
explain select * from t1 where a='aaac';
@ -203,7 +211,6 @@ insert into t1 (name) values ('Matt'), ('Lilu'), ('Corbin'), ('Carly'),
('Suzy'), ('Hoppy'), ('Burrito'), ('Mimi'), ('Sherry'), ('Ben'), ('Phil'),
('Emily'), ('Mike');
insert into t2 select * from t1;
explain select * from t1 where name='matt';
explain select * from t2 where name='matt';
@ -222,12 +229,11 @@ insert into t1 (name) select name from t2;
insert into t1 (name) select name from t2;
insert into t1 (name) select name from t2;
insert into t1 (name) select name from t2;
flush tables;
select count(*) from t1 where name='Matt';
explain select * from t1 ignore index (btree_idx) where name='matt';
show index from t1;
flush tables;
show index from t1;
create table t3
@ -238,8 +244,10 @@ create table t3
) engine=heap;
insert into t3 select name, name from t1;
show index from t3;
flush tables;
show index from t3;
drop table t1,t2;
# test rec_per_key use for joins.
explain select * from t1 ignore key(btree_idx), t3 where t1.name='matt' and t3.a = concat('',t1.name) and t3.b=t1.name;
drop table t1, t2, t3;

19
sql/ha_heap.cc
View File

@ -32,8 +32,14 @@ const char **ha_heap::bas_ext() const
/*
Hash index statistics is updated (copied from HP_KEYDEF::hash_buckets to
rec_per_key) after 1/HEAP_STATS_UPDATE_THRESHOLD records have been inserted/
updated/deleted. delete_all_rows() and table flush cause immediate update.
rec_per_key) after 1/HEAP_STATS_UPDATE_THRESHOLD fraction of table records
have been inserted/updated/deleted. delete_all_rows() and table flush cause
immediate update.
NOTE
hash index statistics must be updated when number of table records changes
from 0 to non-zero value and vice versa. Otherwise records_in_range may
erroneously return 0 and 'range' may miss records.
*/
#define HEAP_STATS_UPDATE_THRESHOLD 10
@ -94,7 +100,6 @@ void ha_heap::set_keys_for_scanning(void)
void ha_heap::update_key_stats()
{
printf("update_key_stats\n");
for (uint i= 0; i < table->keys; i++)
{
KEY *key=table->key_info+i;
@ -425,13 +430,7 @@ ha_rows ha_heap::records_in_range(uint inx, key_range *min_key,
max_key->flag != HA_READ_AFTER_KEY)
return HA_POS_ERROR; // Can only use exact keys
else
{
ha_rows records= file->s->records;
if (!records)
return 0;
ha_rows res= records / file->s->keydef[inx].hash_buckets;
return res ? res : 1;
}
return key->rec_per_key[key->key_parts-1];
}