Commit 34919a03 authored by monty@mashka.mysql.fi's avatar monty@mashka.mysql.fi

Added thread variable max_seeks_for_key

Change optimizer to prefer key lookups before table scan
Change table scans to be done after tables with constrains on scanned table 
parent 5f556f11
No related merge requests found
......@@ -161,7 +161,7 @@ SELECT DISTINCT UserId FROM t1 WHERE UserId=22;
UserId
drop table t1;
CREATE TABLE t1 (a int(10) unsigned not null primary key,b int(10) unsigned);
INSERT INTO t1 VALUES (1,1),(2,1);
INSERT INTO t1 VALUES (1,1),(2,1),(3,1),(4,1);
CREATE TABLE t2 (a int(10) unsigned not null, key (A));
INSERT INTO t2 VALUES (1),(2);
CREATE TABLE t3 (a int(10) unsigned, key(A), b text);
......@@ -189,7 +189,7 @@ insert into t4 select * from t3;
insert into t3 select * from t4;
explain select distinct t1.a from t1,t3 where t1.a=t3.a;
table type possible_keys key key_len ref rows Extra
t1 index PRIMARY PRIMARY 4 NULL 2 Using index; Using temporary
t1 index PRIMARY PRIMARY 4 NULL 4 Using index; Using temporary
t3 ref a a 5 t1.a 10 Using where; Using index; Distinct
select distinct t1.a from t1,t3 where t1.a=t3.a;
a
......@@ -200,16 +200,16 @@ select distinct 1 from t1,t3 where t1.a=t3.a;
1
explain SELECT distinct t1.a from t1;
table type possible_keys key key_len ref rows Extra
t1 index NULL PRIMARY 4 NULL 2 Using index
t1 index NULL PRIMARY 4 NULL 4 Using index
explain SELECT distinct t1.a from t1 order by a desc;
table type possible_keys key key_len ref rows Extra
t1 index NULL PRIMARY 4 NULL 2 Using index
t1 index NULL PRIMARY 4 NULL 4 Using index
explain SELECT t1.a from t1 group by a order by a desc;
table type possible_keys key key_len ref rows Extra
t1 index NULL PRIMARY 4 NULL 2 Using index
t1 index NULL PRIMARY 4 NULL 4 Using index
explain SELECT distinct t1.a from t1 order by a desc limit 1;
table type possible_keys key key_len ref rows Extra
t1 index NULL PRIMARY 4 NULL 2 Using index
t1 index NULL PRIMARY 4 NULL 4 Using index
explain SELECT distinct a from t3 order by a desc limit 2;
table type possible_keys key key_len ref rows Extra
t3 index NULL a 5 NULL 204 Using index
......
......@@ -534,11 +534,11 @@ a b
explain select t1.a,t2.b from t1,t2 where t1.a=t2.a group by t1.a,t2.b;
table type possible_keys key key_len ref rows Extra
t1 ALL NULL NULL NULL NULL 6 Using temporary; Using filesort
t2 ALL a NULL NULL NULL 4 Using where
t2 ALL a NULL NULL NULL 3 Using where
explain select t1.a,t2.b from t1,t2 where t1.a=t2.a group by t1.a,t2.b ORDER BY NULL;
table type possible_keys key key_len ref rows Extra
t1 ALL NULL NULL NULL NULL 6 Using temporary
t2 ALL a NULL NULL NULL 4 Using where
t2 ALL a NULL NULL NULL 3 Using where
drop table t1,t2;
create table t1 (a int, b int);
insert into t1 values (1, 4),(10, 40),(1, 4),(10, 43),(1, 4),(10, 41),(1, 4),(10, 43),(1, 4);
......
......@@ -166,7 +166,7 @@ alter table t1 add column new_col char(1) not null, add key (btn,new_col), drop
update t1 set new_col=btn;
explain select * from t1 where btn="a";
table type possible_keys key key_len ref rows Extra
t1 ALL btn NULL NULL NULL 14 Using where
t1 ALL btn NULL NULL NULL 11 Using where
explain select * from t1 where btn="a" and new_col="a";
table type possible_keys key key_len ref rows Extra
t1 ref btn btn 11 const,const 10 Using where
......
......@@ -104,9 +104,7 @@ KEY category (category,county,state)
INSERT INTO t2 VALUES (3,2,11,12,5400,7800);
INSERT INTO t2 VALUES (4,2,25,12,6500,11200);
INSERT INTO t2 VALUES (5,1,37,6,10000,12000);
select a.id, b.category as catid, b.state as stateid, b.county as
countyid from t1 a, t2 b where (a.token =
'a71250b7ed780f6ef3185bfffe027983') and (a.count = b.id);
select a.id, b.category as catid, b.state as stateid, b.county as countyid from t1 a, t2 b ignore index (primary) where (a.token ='a71250b7ed780f6ef3185bfffe027983') and (a.count = b.id);
id catid stateid countyid
27 2 12 11
28 2 12 11
......
......@@ -36,7 +36,7 @@ a a a a
explain select t1.*,t2.* from t1,t1 as t2 where t1.A=t2.B;
table type possible_keys key key_len ref rows Extra
t1 ALL a NULL NULL NULL 5
t2 ALL b NULL NULL NULL 5 Using where
t2 ALL b NULL NULL NULL 4 Using where
select t1.*,t2.* from t1,t1 as t2 where t1.A=t2.B order by binary t1.a,t2.a;
a b a b
A B a a
......
......@@ -335,12 +335,12 @@ t1 1 c_2 1 c A 5 NULL NULL YES BTREE
t1 1 c_2 2 a A 5 NULL NULL BTREE
explain select * from t1,t2 where t1.a=t2.a;
table type possible_keys key key_len ref rows Extra
t1 ALL a NULL NULL NULL 5
t2 ALL a NULL NULL NULL 2 Using where
t2 ALL a NULL NULL NULL 2
t1 ALL a NULL NULL NULL 4 Using where
explain select * from t1,t2 force index(a) where t1.a=t2.a;
table type possible_keys key key_len ref rows Extra
t2 ALL a NULL NULL NULL 2
t1 ALL a NULL NULL NULL 5 Using where
t1 ALL a NULL NULL NULL 4 Using where
explain select * from t1 force index(a),t2 force index(a) where t1.a=t2.a;
table type possible_keys key key_len ref rows Extra
t2 ALL a NULL NULL NULL 2
......@@ -351,8 +351,8 @@ t2 ALL b NULL NULL NULL 2
t1 ref b b 5 t2.b 1 Using where
explain select * from t1,t2 force index(c) where t1.a=t2.a;
table type possible_keys key key_len ref rows Extra
t1 ALL a NULL NULL NULL 5
t2 ALL NULL NULL NULL NULL 2 Using where
t2 ALL NULL NULL NULL NULL 2
t1 ALL a NULL NULL NULL 4 Using where
explain select * from t1 where a=0 or a=2;
table type possible_keys key key_len ref rows Extra
t1 ALL a NULL NULL NULL 5 Using where
......
......@@ -307,17 +307,17 @@ table type possible_keys key key_len ref rows Extra
t1 range a a 9 NULL 8 Using where; Using index
explain select * from t1 where a = 2 and b >0 order by a desc,b desc;
table type possible_keys key key_len ref rows Extra
t1 range a a 9 NULL 5 Using where; Using index
t1 range a a 9 NULL 4 Using where; Using index
explain select * from t1 where a = 2 and b is null order by a desc,b desc;
table type possible_keys key key_len ref rows Extra
t1 ref a a 9 const,const 1 Using where; Using index; Using filesort
explain select * from t1 where a = 2 and (b is null or b > 0) order by a
desc,b desc;
table type possible_keys key key_len ref rows Extra
t1 range a a 9 NULL 6 Using where; Using index
t1 range a a 9 NULL 5 Using where; Using index
explain select * from t1 where a = 2 and b > 0 order by a desc,b desc;
table type possible_keys key key_len ref rows Extra
t1 range a a 9 NULL 5 Using where; Using index
t1 range a a 9 NULL 4 Using where; Using index
explain select * from t1 where a = 2 and b < 2 order by a desc,b desc;
table type possible_keys key key_len ref rows Extra
t1 range a a 9 NULL 2 Using where; Using index
......
drop table if exists t1;
SET SQL_SAFE_UPDATES=1,SQL_SELECT_LIMIT=4, SQL_MAX_JOIN_SIZE=9;
create table t1 (a int auto_increment primary key, b char(20));
create table t1 (a int auto_increment primary key, b char(20), key(b));
insert into t1 values(1,"test");
SELECT SQL_BUFFER_RESULT * from t1;
a b
......@@ -13,7 +13,7 @@ a b
1 test
2 test2
update t1 set b="a" where a=1;
select 1 from t1,t1 as t2,t1 as t3,t1 as t4;
select 1 from t1,t1 as t2,t1 as t3;
1
1
1
......@@ -22,11 +22,9 @@ select 1 from t1,t1 as t2,t1 as t3,t1 as t4;
update t1 set b="a";
You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
update t1 set b="a" where b="test";
You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
delete from t1;
You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
delete from t1 where b="test";
You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
delete from t1 where a+0=1;
You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
select 1 from t1,t1 as t2,t1 as t3,t1 as t4,t1 as t5;
......@@ -59,5 +57,22 @@ a b
2 test2
4 a
5 a
SELECT @@MAX_SEEKS_FOR_KEY;
@@max_seeks_for_key
4294967295
analyze table t1;
Table Op Msg_type Msg_text
test.t1 analyze status OK
insert into t1 values (null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a");
explain select * from t1,t1 as t2 where t1.b=t2.b;
table type possible_keys key key_len ref rows Extra
t1 ALL b NULL NULL NULL 21
t2 ALL b NULL NULL NULL 16 Using where
set MAX_SEEKS_FOR_KEY=1;
explain select * from t1,t1 as t2 where t1.b=t2.b;
table type possible_keys key key_len ref rows Extra
t1 ALL b NULL NULL NULL 21
t2 ref b b 21 t1.b 6 Using where
SET MAX_SEEKS_FOR_KEY=DEFAULT;
drop table t1;
SET SQL_SAFE_UPDATES=0,SQL_SELECT_LIMIT=DEFAULT, SQL_MAX_JOIN_SIZE=DEFAULT;
......@@ -60,7 +60,7 @@ drop table t1;
#
CREATE TABLE t1 (a int(10) unsigned not null primary key,b int(10) unsigned);
INSERT INTO t1 VALUES (1,1),(2,1);
INSERT INTO t1 VALUES (1,1),(2,1),(3,1),(4,1);
CREATE TABLE t2 (a int(10) unsigned not null, key (A));
INSERT INTO t2 VALUES (1),(2);
CREATE TABLE t3 (a int(10) unsigned, key(A), b text);
......
......@@ -98,10 +98,7 @@ CREATE TABLE t2 (
INSERT INTO t2 VALUES (3,2,11,12,5400,7800);
INSERT INTO t2 VALUES (4,2,25,12,6500,11200);
INSERT INTO t2 VALUES (5,1,37,6,10000,12000);
select a.id, b.category as catid, b.state as stateid, b.county as
countyid from t1 a, t2 b where (a.token =
'a71250b7ed780f6ef3185bfffe027983') and (a.count = b.id);
select a.id, b.category as catid, b.state as stateid, b.county as countyid from t1 a, t2 b ignore index (primary) where (a.token ='a71250b7ed780f6ef3185bfffe027983') and (a.count = b.id);
select a.id, b.category as catid, b.state as stateid, b.county as
countyid from t1 a, t2 b where (a.token =
'a71250b7ed780f6ef3185bfffe027983') and (a.count = b.id) order by a.id;
......
......@@ -4,7 +4,7 @@
drop table if exists t1;
SET SQL_SAFE_UPDATES=1,SQL_SELECT_LIMIT=4, SQL_MAX_JOIN_SIZE=9;
create table t1 (a int auto_increment primary key, b char(20));
create table t1 (a int auto_increment primary key, b char(20), key(b));
insert into t1 values(1,"test");
SELECT SQL_BUFFER_RESULT * from t1;
update t1 set b="a" where a=1;
......@@ -12,7 +12,7 @@ delete from t1 where a=1;
insert into t1 values(1,"test"),(2,"test2");
SELECT SQL_BUFFER_RESULT * from t1;
update t1 set b="a" where a=1;
select 1 from t1,t1 as t2,t1 as t3,t1 as t4;
select 1 from t1,t1 as t2,t1 as t3;
# The following should give errors:
--error 1175
......@@ -49,6 +49,17 @@ SELECT * from t1;
SET MAX_JOIN_SIZE=DEFAULT;
SELECT * from t1;
#
# Test MAX_SEEKS_FOR_KEY
#
SELECT @@MAX_SEEKS_FOR_KEY;
analyze table t1;
insert into t1 values (null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a");
explain select * from t1,t1 as t2 where t1.b=t2.b;
set MAX_SEEKS_FOR_KEY=1;
explain select * from t1,t1 as t2 where t1.b=t2.b;
SET MAX_SEEKS_FOR_KEY=DEFAULT;
drop table t1;
SET SQL_SAFE_UPDATES=0,SQL_SELECT_LIMIT=DEFAULT, SQL_MAX_JOIN_SIZE=DEFAULT;
......@@ -184,40 +184,41 @@ class handler :public Sql_alloc
{
protected:
struct st_table *table; /* The table definition */
uint active_index;
public:
byte *ref; /* Pointer to current row */
byte *dupp_ref; /* Pointer to dupp row */
uint ref_length; /* Length of ref (1-8 or the clustered
key length) */
uint block_size; /* index block size */
ha_rows records; /* Records i datafilen */
ha_rows deleted; /* Deleted records */
ulonglong data_file_length; /* Length off data file */
ulonglong max_data_file_length; /* Length off data file */
ulonglong index_file_length;
ulonglong max_index_file_length;
ulonglong delete_length; /* Free bytes */
ulonglong auto_increment_value;
uint raid_type,raid_chunks;
ha_rows records; /* Records in table */
ha_rows deleted; /* Deleted records */
ulong raid_chunksize;
uint errkey; /* Last dup key */
uint sortkey, key_used_on_scan;
ulong mean_rec_length; /* physical reclength */
time_t create_time; /* When table was created */
time_t check_time;
time_t update_time;
ulong mean_rec_length; /* physical reclength */
uint errkey; /* Last dup key */
uint sortkey, key_used_on_scan;
uint active_index;
/* Length of ref (1-8 or the clustered key length) */
uint ref_length;
uint block_size; /* index block size */
uint raid_type,raid_chunks;
FT_INFO *ft_handler;
bool auto_increment_column_changed;
handler(TABLE *table_arg) : table(table_arg),active_index(MAX_REF_PARTS),
ref(0),ref_length(sizeof(my_off_t)), block_size(0),records(0),deleted(0),
data_file_length(0), max_data_file_length(0), index_file_length(0),
delete_length(0), auto_increment_value(0), raid_type(0),
key_used_on_scan(MAX_KEY),
create_time(0), check_time(0), update_time(0), mean_rec_length(0),
ft_handler(0)
handler(TABLE *table_arg) :table(table_arg),
ref(0), data_file_length(0), max_data_file_length(0), index_file_length(0),
delete_length(0), auto_increment_value(0),
records(0), deleted(0), mean_rec_length(0),
create_time(0), check_time(0), update_time(0),
key_used_on_scan(MAX_KEY), active_index(MAX_REF_PARTS),
ref_length(sizeof(my_off_t)), block_size(0),
raid_type(0), ft_handler(0)
{}
virtual ~handler(void) {}
int ha_open(const char *name, int mode, int test_if_locked);
......@@ -227,7 +228,7 @@ public:
uint get_dup_key(int error);
void change_table_ptr(TABLE *table_arg) { table=table_arg; }
virtual double scan_time()
{ return ulonglong2double(data_file_length) / IO_SIZE + 1; }
{ return ulonglong2double(data_file_length) / IO_SIZE + 2; }
virtual double read_time(uint index, uint ranges, ha_rows rows)
{ return rows2double(ranges+rows); }
virtual bool fast_key_read() { return 0;}
......
......@@ -1175,8 +1175,8 @@ Item_cond::fix_fields(THD *thd,TABLE_LIST *tables)
List_iterator<Item> li(list);
Item *item;
char buff[sizeof(char*)]; // Max local vars in function
used_tables_cache=0;
const_item_cache=0;
not_null_tables_cache= used_tables_cache= 0;
const_item_cache= 0;
/*
and_table_cache is the value that Item_cond_or() returns for
not_null_tables()
......
......@@ -3154,7 +3154,7 @@ enum options {
OPT_MAX_BINLOG_CACHE_SIZE, OPT_MAX_BINLOG_SIZE,
OPT_MAX_CONNECTIONS, OPT_MAX_CONNECT_ERRORS,
OPT_MAX_DELAYED_THREADS, OPT_MAX_HEP_TABLE_SIZE,
OPT_MAX_JOIN_SIZE, OPT_MAX_SORT_LENGTH,
OPT_MAX_JOIN_SIZE, OPT_MAX_SORT_LENGTH, OPT_MAX_SEEKS_FOR_KEY,
OPT_MAX_TMP_TABLES, OPT_MAX_USER_CONNECTIONS,
OPT_MAX_WRITE_LOCK_COUNT, OPT_BULK_INSERT_BUFFER_SIZE,
OPT_MYISAM_BLOCK_SIZE, OPT_MYISAM_MAX_EXTRA_SORT_FILE_SIZE,
......@@ -3832,6 +3832,11 @@ replicating a LOAD DATA INFILE command",
(gptr*) &global_system_variables.max_join_size,
(gptr*) &max_system_variables.max_join_size, 0, GET_HA_ROWS, REQUIRED_ARG,
~0L, 1, ~0L, 0, 1, 0},
{ "max_seeks_for_key", OPT_MAX_SEEKS_FOR_KEY,
"Limit assumed max number of seeks when looking up rows based on a key",
(gptr*) &global_system_variables.max_seeks_for_key,
(gptr*) &max_system_variables.max_seeks_for_key, 0, GET_ULONG,
REQUIRED_ARG, ~0L, 1, ~0L, 0, 1, 0 },
{"max_sort_length", OPT_MAX_SORT_LENGTH,
"The number of bytes to use when sorting BLOB or TEXT values (only the first max_sort_length bytes of each value are used; the rest are ignored).",
(gptr*) &global_system_variables.max_sort_length,
......
......@@ -154,6 +154,8 @@ sys_var_thd_ulong sys_max_heap_table_size("max_heap_table_size",
sys_var_thd_ha_rows sys_max_join_size("max_join_size",
&SV::max_join_size,
fix_max_join_size);
sys_var_thd_ulong sys_max_seeks_for_key("max_seeks_for_key",
&SV::max_seeks_for_key);
#ifndef TO_BE_DELETED /* Alias for max_join_size */
sys_var_thd_ha_rows sys_sql_max_join_size("sql_max_join_size",
&SV::max_join_size,
......@@ -348,6 +350,7 @@ sys_var *sys_variables[]=
&sys_max_delayed_threads,
&sys_max_heap_table_size,
&sys_max_join_size,
&sys_max_seeks_for_key,
&sys_max_sort_length,
&sys_max_tmp_tables,
&sys_max_user_connections,
......@@ -492,6 +495,7 @@ struct show_var_st init_vars[]= {
{sys_max_delayed_threads.name,(char*) &sys_max_delayed_threads, SHOW_SYS},
{sys_max_heap_table_size.name,(char*) &sys_max_heap_table_size, SHOW_SYS},
{sys_max_join_size.name, (char*) &sys_max_join_size, SHOW_SYS},
{sys_max_seeks_for_key.name, (char*) &sys_max_seeks_for_key, SHOW_SYS},
{sys_max_sort_length.name, (char*) &sys_max_sort_length, SHOW_SYS},
{sys_max_user_connections.name,(char*) &sys_max_user_connections, SHOW_SYS},
{sys_max_tmp_tables.name, (char*) &sys_max_tmp_tables, SHOW_SYS},
......
......@@ -310,6 +310,7 @@ struct system_variables
ulong tx_isolation;
ulong table_type;
ulong default_week_format;
ulong max_seeks_for_key;
my_bool log_warnings;
my_bool low_priority_updates;
......
......@@ -1271,14 +1271,14 @@ make_join_statistics(JOIN *join,TABLE_LIST *tables,COND *conds,
/*
Set a max range of how many seeks we can expect when using keys
This was (s->read_time*5), but this was too low with small rows
This is can't be to high as otherwise we are likely to use
table scan.
*/
s->worst_seeks= (double) s->found_records / 5;
s->worst_seeks= min((double) s->found_records / 10,
(double) s->read_time*3);
if (s->worst_seeks < 2.0) // Fix for small tables
s->worst_seeks=2.0;
/* if (s->type == JT_EQ_REF)
continue; */
if (s->const_keys)
{
ha_rows records;
......@@ -1884,6 +1884,7 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
best=best_time=records=DBL_MAX;
KEYUSE *best_key=0;
uint best_max_key_part=0;
my_bool found_constrain= 0;
if (s->keyuse)
{ /* Use key if possible */
......@@ -1964,6 +1965,7 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
}
else
{
found_constrain= 1;
/*
Check if we found full key
*/
......@@ -2000,16 +2002,18 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
records=2.0; // Can't be as good as a unique
}
}
/* Limit the number of matched rows */
tmp= records;
set_if_smaller(tmp, (double) thd->variables.max_seeks_for_key);
if (table->used_keys & ((key_map) 1 << key))
{
/* we can use only index tree */
uint keys_per_block= table->file->block_size/2/
(keyinfo->key_length+table->file->ref_length)+1;
tmp=(record_count*(records+keys_per_block-1)/
keys_per_block);
tmp=record_count*(tmp+keys_per_block-1)/keys_per_block;
}
else
tmp=record_count*min(records,s->worst_seeks);
tmp=record_count*min(tmp,s->worst_seeks);
}
}
else
......@@ -2039,7 +2043,7 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
{
/*
Assume that the first key part matches 1% of the file
and that the hole key matches 10 (dupplicates) or 1
and that the hole key matches 10 (duplicates) or 1
(unique) records.
Assume also that more key matches proportionally more
records
......@@ -2071,6 +2075,8 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
records=(ulong) tmp;
}
}
/* Limit the number of matched rows */
set_if_smaller(tmp, (double) thd->variables.max_seeks_for_key);
if (table->used_keys & ((key_map) 1 << key))
{
/* we can use only index tree */
......@@ -2113,20 +2119,31 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
s->table->used_keys && best_key) &&
!(s->table->force_index && best_key))
{ // Check full join
ha_rows rnd_records= s->found_records;
if (s->on_expr)
{
tmp=rows2double(s->found_records); // Can't use read cache
tmp=rows2double(rnd_records); // Can't use read cache
}
else
{
tmp=(double) s->read_time;
/* Calculate time to read through cache */
/* Calculate time to read previous rows through cache */
tmp*=(1.0+floor((double) cache_record_length(join,idx)*
record_count /
(double) thd->variables.join_buff_size));
}
/*
If there is a restriction on the table, assume that 25% of the
rows can be skipped on next part.
This is to force tables that this table depends on before this
table
*/
if (found_constrain)
rnd_records-= rnd_records/4;
if (best == DBL_MAX ||
(tmp + record_count/(double) TIME_FOR_COMPARE*s->found_records <
(tmp + record_count/(double) TIME_FOR_COMPARE*rnd_records <
best + record_count/(double) TIME_FOR_COMPARE*records))
{
/*
......@@ -2134,7 +2151,7 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
will ensure that this will be used
*/
best=tmp;
records= rows2double(s->found_records);
records= rows2double(rnd_records);
best_key=0;
}
}
......
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