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MWL#17: Table elimination

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- More dbug printouts
- More testcases
This commit is contained in:
Sergey Petrunya
2009-08-17 18:02:29 +03:00
parent a14b5d2466
commit 441434e565
3 changed files with 49 additions and 6 deletions
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17
mysql-test/r/table_elim.result
View File

@@ -202,3 +202,20 @@ t2.pk3=t2.pk1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 4
drop table t1, t2;
create table t1 (pk int primary key, col int);
insert into t1 values (1,1),(2,2);
create table t2 like t1;
insert into t2 select * from t1;
create table t3 like t1;
insert into t3 select * from t1;
explain
select t1.* from t1 left join ( t2 left join t3 on t3.pk=t2.col) on t2.col=t1.col;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 2
1 SIMPLE t2 ALL NULL NULL NULL NULL 2
explain
select t1.*, t2.* from t1 left join (t2 left join t3 on t3.pk=t2.col) on t2.pk=t1.col;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 2
1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t1.col 1
drop table t1, t2;

19
mysql-test/t/table_elim.test
View File

@@ -157,4 +157,23 @@ explain select t1.* from t1 left join t2 on t2.pk2=t1.a and
t2.pk3=t2.pk1;
drop table t1, t2;
#
# Check that equality propagation is taken into account
#
create table t1 (pk int primary key, col int);
insert into t1 values (1,1),(2,2);
create table t2 like t1;
insert into t2 select * from t1;
create table t3 like t1;
insert into t3 select * from t1;
explain
select t1.* from t1 left join ( t2 left join t3 on t3.pk=t2.col) on t2.col=t1.col;
explain
select t1.*, t2.* from t1 left join (t2 left join t3 on t3.pk=t2.col) on t2.pk=t1.col;
drop table t1, t2;

19
sql/opt_table_elimination.cc
View File

@@ -136,7 +136,8 @@ class Table_elimination;
/*
A value.
A value, something that can be bound or not bound. Also, values can be linked
in a list.
*/
class Value_dep : public Sql_alloc
@@ -203,7 +204,7 @@ public:
/*
A 'module'
A 'module'. Module has dependencies
*/
class Module_dep : public Sql_alloc
@@ -227,7 +228,6 @@ public:
};
/*
A "tbl.column= expr" equality dependency. tbl.column depends on fields
used in expr.
@@ -333,6 +333,9 @@ Equality_module *merge_func_deps(Equality_module *start, Equality_module *new_fi
static Table_value *get_table_value(Table_elimination *te, TABLE *table);
static Field_value *get_field_value(Table_elimination *te, Field *field);
static Outer_join_module *get_outer_join_dep(Table_elimination *te,
TABLE_LIST *outer_join,
table_map deps_map);
static
void run_elimination_wave(Table_elimination *te, Module_dep *bound_modules);
void eliminate_tables(JOIN *join);
@@ -1212,15 +1215,19 @@ void run_elimination_wave(Table_elimination *te, Module_dep *bound_modules)
- expressions that depend on us.
*/
Field_value *field_dep= (Field_value*)bound_values;
DBUG_PRINT("info", ("field %s.%s is now bound",
field_dep->field->table->alias,
field_dep->field->field_name));
for (Key_module *key_dep= field_dep->table->keys; key_dep;
key_dep= key_dep->next_table_key)
{
DBUG_PRINT("info", ("key %s.%s is now bound",
key_dep->table->table->alias,
key_dep->table->table->key_info[key_dep->keyno].name));
if (field_dep->field->part_of_key.is_set(key_dep->keyno) &&
key_dep->unknown_args && !--key_dep->unknown_args)
{
DBUG_PRINT("info", ("key %s.%s is now bound",
key_dep->table->table->alias,
key_dep->table->table->key_info[key_dep->keyno].name));
/* Mark as bound and add to the list */
key_dep->next= bound_modules;
bound_modules= key_dep;