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Fixed LP bug#672497.

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Miscalculation of the minimum possible buffer size could trigger
an assert in JOIN_CACHE_HASHED::put_record when if join_buffer_size
was set to the values that is less than the length of one record to
stored in the join buffer.
It happened due to the following mistakes:
- underestimation of space needed for a key in the hash table
  (we have to take into account that hash table can have more
  buckets than the expected number of records).
- the value of maximum total length of all records stored in
  the join buffer was not saved in the field max_used_fieldlength
  by the function calc_used_field_length.
This commit is contained in:
Igor Babaev 2010-11-11 15:35:11 -08:00
parent 74d18e93c6
commit 92772d6d46
4 changed files with 125 additions and 6 deletions
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55
mysql-test/r/join_cache.result
View file

@ -5675,4 +5675,59 @@ f 5
f 5
SET SESSION join_cache_level = DEFAULT;
DROP TABLE t1,t2;
#
# Bug #672497: 3 way join with tiny incremental join buffer with
# and a ref access from the first table
#
CREATE TABLE t1 (
pk int PRIMARY KEY,
v varchar(10) CHARACTER SET latin1 COLLATE latin1_bin DEFAULT NULL,
INDEX idx (v)
);
INSERT INTO t1 VALUES
(1,'abcdefjhjk'), (2,'i'),(3,'abcdefjhjk'), (4,'well'), (5,'abcdefjhjk'),
(6,'abcdefjhjk'), (7,'that');
CREATE TABLE t2 (
pk int PRIMARY KEY,
i int DEFAULT NULL,
v varchar(1000) CHARACTER SET latin1 COLLATE latin1_bin DEFAULT NULL,
INDEX idx (v)
);
INSERT INTO t2 VALUES
(1,6,'yes'), (2,NULL,'will'), (3,NULL,'o'), (4,NULL,'k'), (5,NULL,'she'),
(6,-1450835968,'abcdefjhjkl'), (7,-975831040,'abcdefjhjkl'), (8,NULL,'z'),
(10,-343932928,'t'),
(11,6,'yes'), (12,NULL,'will'), (13,NULL,'o'), (14,NULL,'k'), (15,NULL,'she'),
(16,-1450835968,'abcdefjhjkl'), (17,-975831040,'abcdefjhjkl'), (18,NULL,'z'),
(19,-343932928,'t');
CREATE TABLE t3 (
pk int NOT NULL PRIMARY KEY,
i int,
v varchar(1024) CHARACTER SET utf8 COLLATE utf8_bin DEFAULT NULL,
INDEX idx (v(333))
);
INSERT INTO t3 VALUES
(1,7,'abcdefjhjkl'),(2,6,'y'), (3,NULL,'to'),(4,7,'n'),(5,7,'look'), (6,NULL,'all'),
(7,1443168256,'c'), (8,1427046400,'right'),
(11,7,'abcdefjhjkl'), (12,6,'y'), (13,NULL,'to'), (14,7,'n'), (15,7,'look'),
(16,NULL,'all'), (17,1443168256,'c'), (18,1427046400,'right'),
(21,7,'abcdefjhjkl'), (22,6,'y'), (23,NULL,'to'), (24,7,'n'), (25,7,'look'),
(26,NULL,'all'), (27,1443168256,'c'), (28,1427046400,'right'),
(31,7,'abcdefjhjkl'), (32,6,'y'), (33,NULL,'to'), (34,7,'n'), (35,7,'look'),
(36,NULL,'all'), (37,1443168256,'c'), (38,1427046400,'right');
SET SESSION join_buffer_size = 192;
SET SESSION join_cache_level = 4;
EXPLAIN
SELECT t3.i FROM t1,t2,t3
WHERE t1.v = t2.v AND t3.v = t1.v AND t2.i <> 0;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index idx idx 13 NULL 7 Using where; Using index
1 SIMPLE t2 ref idx idx 1003 test.t1.v 2 Using where; Using join buffer (flat, BNLH join)
1 SIMPLE t3 ref idx idx 1002 func 3 Using where; Using join buffer (incremental, BNLH join)
SELECT t3.i FROM t1,t2,t3
WHERE t1.v = t2.v AND t3.v = t1.v AND t2.i <> 0;
i
SET SESSION join_cache_level = DEFAULT;
SET SESSION join_buffer_size = DEFAULT;
DROP TABLE t1,t2,t3;
set @@optimizer_switch=@save_optimizer_switch;

58
mysql-test/t/join_cache.test
View file

@ -2358,5 +2358,63 @@ SET SESSION join_cache_level = DEFAULT;
DROP TABLE t1,t2;
--echo #
--echo # Bug #672497: 3 way join with tiny incremental join buffer with
--echo # and a ref access from the first table
--echo #
CREATE TABLE t1 (
pk int PRIMARY KEY,
v varchar(10) CHARACTER SET latin1 COLLATE latin1_bin DEFAULT NULL,
INDEX idx (v)
);
INSERT INTO t1 VALUES
(1,'abcdefjhjk'), (2,'i'),(3,'abcdefjhjk'), (4,'well'), (5,'abcdefjhjk'),
(6,'abcdefjhjk'), (7,'that');
CREATE TABLE t2 (
pk int PRIMARY KEY,
i int DEFAULT NULL,
v varchar(1000) CHARACTER SET latin1 COLLATE latin1_bin DEFAULT NULL,
INDEX idx (v)
);
INSERT INTO t2 VALUES
(1,6,'yes'), (2,NULL,'will'), (3,NULL,'o'), (4,NULL,'k'), (5,NULL,'she'),
(6,-1450835968,'abcdefjhjkl'), (7,-975831040,'abcdefjhjkl'), (8,NULL,'z'),
(10,-343932928,'t'),
(11,6,'yes'), (12,NULL,'will'), (13,NULL,'o'), (14,NULL,'k'), (15,NULL,'she'),
(16,-1450835968,'abcdefjhjkl'), (17,-975831040,'abcdefjhjkl'), (18,NULL,'z'),
(19,-343932928,'t');
CREATE TABLE t3 (
pk int NOT NULL PRIMARY KEY,
i int,
v varchar(1024) CHARACTER SET utf8 COLLATE utf8_bin DEFAULT NULL,
INDEX idx (v(333))
);
INSERT INTO t3 VALUES
(1,7,'abcdefjhjkl'),(2,6,'y'), (3,NULL,'to'),(4,7,'n'),(5,7,'look'), (6,NULL,'all'),
(7,1443168256,'c'), (8,1427046400,'right'),
(11,7,'abcdefjhjkl'), (12,6,'y'), (13,NULL,'to'), (14,7,'n'), (15,7,'look'),
(16,NULL,'all'), (17,1443168256,'c'), (18,1427046400,'right'),
(21,7,'abcdefjhjkl'), (22,6,'y'), (23,NULL,'to'), (24,7,'n'), (25,7,'look'),
(26,NULL,'all'), (27,1443168256,'c'), (28,1427046400,'right'),
(31,7,'abcdefjhjkl'), (32,6,'y'), (33,NULL,'to'), (34,7,'n'), (35,7,'look'),
(36,NULL,'all'), (37,1443168256,'c'), (38,1427046400,'right');
SET SESSION join_buffer_size = 192;
SET SESSION join_cache_level = 4;
EXPLAIN
SELECT t3.i FROM t1,t2,t3
WHERE t1.v = t2.v AND t3.v = t1.v AND t2.i <> 0;
SELECT t3.i FROM t1,t2,t3
WHERE t1.v = t2.v AND t3.v = t1.v AND t2.i <> 0;
SET SESSION join_cache_level = DEFAULT;
SET SESSION join_buffer_size = DEFAULT;
DROP TABLE t1,t2,t3;
# this must be the last command in the file
set @@optimizer_switch=@save_optimizer_switch;

9
sql/sql_join_cache.cc
View file

@ -731,7 +731,7 @@ ulong JOIN_CACHE::get_min_join_buffer_size()
ulong len= 0;
for (JOIN_TAB *tab= join_tab-tables; tab < join_tab; tab++)
len+= tab->get_max_used_fieldlength();
len+= get_record_max_affix_length() + get_max_key_addon_space_per_record();
len+= get_record_max_affix_length() + get_max_key_addon_space_per_record();
ulong min_sz= len*min_records;
ulong add_sz= 0;
for (uint i=0; i < min_records; i++)
@ -2633,10 +2633,15 @@ uint JOIN_CACHE_HASHED::get_max_key_addon_space_per_record()
{
ulong len;
TABLE_REF *ref= &join_tab->ref;
/*
The total number of hash entries in the hash tables is bounded by
ceiling(N/0.7) where N is the maximum number of records in the buffer.
That's why the multiplier 2 is used in the formula below.
*/
len= (use_emb_key ? get_size_of_rec_offset() : ref->key_length) +
size_of_rec_ofs + // size of the key chain header
size_of_rec_ofs + // >= size of the reference to the next key
size_of_rec_ofs; // >= size of hash table entry
2*size_of_rec_ofs; // >= 2*( size of hash table entry)
return len;
}

9
sql/sql_select.cc
View file

@ -5925,16 +5925,17 @@ void JOIN_TAB::calc_used_field_length(bool max_fl)
rec_length+=sizeof(my_bool);
if (max_fl)
{
// TODO: to improve this estimate for max expected length if the record
// TODO: to improve this estimate for max expected length
if (blobs)
{
uint blob_length=(uint) (table->file->stats.mean_rec_length-
(table->s->reclength-rec_length));
rec_length+=(uint) max(4,blob_length);
rec_length+=(uint) max(sizeof(void*) * blobs, blob_length);
}
max_used_fieldlength= rec_length;
}
else
rec_length= table->file->stats.mean_rec_length;
else if (table->file->stats.mean_rec_length)
set_if_smaller(rec_length, table->file->stats.mean_rec_length);
/*
psergey-todo: why we don't count here rowid that we might need to store