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mariadb/mysql-test/r/explain_json.result
Sergei Petrunia 461dbd80d2 EXPLAIN FORMAT=JSON: support join buffering 
- Basic support for JOIN buffering
- The output is not polished but catches the main point:
  tab->select_cond and tab->cache_select->cond are printed separately.
- Hash join support is poor still.

- Also fixed identation in JOIN_TAB::save_explain_data
2014-11-27 23:10:44 +03:00

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drop table if exists t0,t1;
create table t0(a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
explain format=json select * from t0;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
}
explain format=json select * from t0 where 1>2;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"message": "Impossible WHERE"
}
}
}
explain format=json select * from t0 where a<3;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(t0.a < 3)"
}
}
}
# Try a basic join
create table t1 (a int, b int, filler char(32), key(a));
insert into t1
select
a.a + b.a* 10 + c.a * 100,
a.a + b.a* 10 + c.a * 100,
'filler'
from t0 a, t0 b, t0 c;
explain format=json select * from t0,t1 where t1.a=t0.a;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(t0.a is not null)"
},
"table": {
"table_name": "t1",
"access_type": "ref",
"possible_keys": ["a"],
"key": "a",
"key_length": "5",
"used_key_parts": ["a"],
"ref": ["test.t0.a"],
"rows": 1,
"filtered": 100
}
}
}
# Try range and index_merge
create table t2 (a1 int, a2 int, b1 int, b2 int, key(a1,a2), key(b1,b2));
insert into t2 select a,a,a,a from t1;
explain format=json select * from t2 where a1<5;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t2",
"access_type": "range",
"possible_keys": ["a1"],
"key": "a1",
"key_length": "5",
"used_key_parts": ["a1"],
"rows": 5,
"filtered": 100,
"index_condition": "(t2.a1 < 5)"
}
}
}
explain format=json select * from t2 where a1=1 or b1=2;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t2",
"access_type": "index_merge",
"possible_keys": ["a1", "b1"],
"key_length": "5,5",
"index_merge": {
"sort_union": {
"range": {
"key": "a1",
"used_key_parts": ["a1"]
},
"range": {
"key": "b1",
"used_key_parts": ["b1"]
}
}
},
"rows": 2,
"filtered": 100,
"attached_condition": "((t2.a1 = 1) or (t2.b1 = 2))"
}
}
}
explain format=json select * from t2 where a1=1 or (b1=2 and b2=3);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t2",
"access_type": "index_merge",
"possible_keys": ["a1", "b1"],
"key_length": "5,10",
"index_merge": {
"sort_union": {
"range": {
"key": "a1",
"used_key_parts": ["a1"]
},
"range": {
"key": "b1",
"used_key_parts": ["b1", "b2"]
}
}
},
"rows": 2,
"filtered": 100,
"attached_condition": "((t2.a1 = 1) or ((t2.b1 = 2) and (t2.b2 = 3)))"
}
}
}
# Try ref access on two key components
explain format=json select * from t0,t2 where t2.b1=t0.a and t2.b2=4;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(t0.a is not null)"
},
"table": {
"table_name": "t2",
"access_type": "ref",
"possible_keys": ["b1"],
"key": "b1",
"key_length": "10",
"used_key_parts": ["b1", "b2"],
"ref": ["test.t0.a", "const"],
"rows": 1,
"filtered": 100
}
}
}
drop table t1,t2;
#
# Try a UNION
#
explain format=json select * from t0 A union select * from t0 B;
EXPLAIN
{
"query_block": {
"union_result": {
"table_name": "<union1,2>",
"access_type": "ALL",
"query_specifications": [
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "A",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
},
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "B",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
}
]
}
}
}
explain format=json select * from t0 A union all select * from t0 B;
EXPLAIN
{
"query_block": {
"union_result": {
"table_name": "<union1,2>",
"access_type": "ALL",
"query_specifications": [
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "A",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
},
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "B",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
}
]
}
}
}
#
# Subqueries
#
create table t1 (a int, b int);
insert into t1 select a,a from t0;
explain format=json select a, a > (select max(b) from t1 where t1.b=t0.a) from t0;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"filtered": 100
},
"subqueries": [
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(t1.b = t0.a)"
}
}
}
]
}
}
explain format=json
select * from t0 where
a > (select max(b) from t1 where t1.b=t0.a) or a < 3 ;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "((t0.a > (subquery#2)) or (t0.a < 3))"
},
"subqueries": [
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(t1.b = t0.a)"
}
}
}
]
}
}
drop table t1;
#
# Join buffering
#
create table t1 (a int, b int);
insert into t1 select A.a+10*B.a, A.a+10*B.a from t0 A, t0 B;
explain format=json
select * from t1 A, t1 B where A.a=B.a and A.b < 3 and B.b < 5;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "A",
"access_type": "ALL",
"rows": 100,
"filtered": 100,
"attached_condition": "(A.b < 3)"
},
"block-nl-join": {
"table": {
"table_name": "B",
"access_type": "ALL",
"rows": 100,
"filtered": 100,
"attached_condition": "(B.b < 5)"
},
"buffer_type": "flat",
"join_type": "BNL",
"attached_condition": "(B.a = A.a)"
}
}
}
drop table t1;
drop table t0;
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