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1053 lines
27 KiB
1053 lines
27 KiB
drop table if exists t0,t1,t2;
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create table t0(a int);
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insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
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explain format=json select * from t0;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "t0",
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"access_type": "ALL",
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"rows": 10,
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"filtered": 100
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}
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}
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}
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explain format=json select * from t0 where 1>2;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"message": "Impossible WHERE"
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}
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}
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}
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explain format=json select * from t0 where a<3;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "t0",
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"access_type": "ALL",
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"rows": 10,
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"filtered": 100,
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"attached_condition": "(t0.a < 3)"
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}
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}
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}
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# Try a basic join
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create table t1 (a int, b int, filler char(32), key(a));
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insert into t1
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select
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a.a + b.a* 10 + c.a * 100,
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a.a + b.a* 10 + c.a * 100,
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'filler'
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from t0 a, t0 b, t0 c;
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explain format=json select * from t0,t1 where t1.a=t0.a;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "t0",
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"access_type": "ALL",
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"rows": 10,
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"filtered": 100,
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"attached_condition": "(t0.a is not null)"
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},
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"table": {
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"table_name": "t1",
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"access_type": "ref",
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"possible_keys": ["a"],
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"key": "a",
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"key_length": "5",
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"used_key_parts": ["a"],
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"ref": ["test.t0.a"],
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"rows": 1,
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"filtered": 100
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}
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}
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}
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# Try range and index_merge
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create table t2 (a1 int, a2 int, b1 int, b2 int, key(a1,a2), key(b1,b2));
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insert into t2 select a,a,a,a from t1;
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explain format=json select * from t2 where a1<5;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "t2",
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"access_type": "range",
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"possible_keys": ["a1"],
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"key": "a1",
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"key_length": "5",
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"used_key_parts": ["a1"],
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"rows": 5,
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"filtered": 100,
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"index_condition": "(t2.a1 < 5)"
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}
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}
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}
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explain format=json select * from t2 where a1=1 or b1=2;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "t2",
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"access_type": "index_merge",
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"possible_keys": ["a1", "b1"],
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"key_length": "5,5",
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"index_merge": {
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"sort_union": {
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"range": {
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"key": "a1",
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"used_key_parts": ["a1"]
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},
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"range": {
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"key": "b1",
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"used_key_parts": ["b1"]
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}
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}
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},
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"rows": 2,
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"filtered": 100,
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"attached_condition": "((t2.a1 = 1) or (t2.b1 = 2))"
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}
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}
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}
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explain format=json select * from t2 where a1=1 or (b1=2 and b2=3);
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "t2",
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"access_type": "index_merge",
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"possible_keys": ["a1", "b1"],
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"key_length": "5,10",
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"index_merge": {
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"sort_union": {
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"range": {
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"key": "a1",
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"used_key_parts": ["a1"]
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},
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"range": {
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"key": "b1",
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"used_key_parts": ["b1", "b2"]
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}
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}
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},
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"rows": 2,
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"filtered": 100,
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"attached_condition": "((t2.a1 = 1) or ((t2.b1 = 2) and (t2.b2 = 3)))"
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}
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}
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}
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explain format=json select * from t2 where (a1=1 and a2=1) or
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(b1=2 and b2=1);
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "t2",
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"access_type": "index_merge",
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"possible_keys": ["a1", "b1"],
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"key_length": "10,10",
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"index_merge": {
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"union": {
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"range": {
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"key": "a1",
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"used_key_parts": ["a1", "a2"]
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},
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"range": {
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"key": "b1",
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"used_key_parts": ["b1", "b2"]
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}
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}
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},
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"rows": 2,
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"filtered": 100,
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"attached_condition": "(((t2.a1 = 1) and (t2.a2 = 1)) or ((t2.b1 = 2) and (t2.b2 = 1)))"
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}
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}
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}
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# Try ref access on two key components
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explain format=json select * from t0,t2 where t2.b1=t0.a and t2.b2=4;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "t0",
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"access_type": "ALL",
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"rows": 10,
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"filtered": 100,
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"attached_condition": "(t0.a is not null)"
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},
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"table": {
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"table_name": "t2",
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"access_type": "ref",
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"possible_keys": ["b1"],
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"key": "b1",
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"key_length": "10",
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"used_key_parts": ["b1", "b2"],
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"ref": ["test.t0.a", "const"],
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"rows": 1,
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"filtered": 100
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}
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}
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}
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drop table t1,t2;
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#
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# Try a UNION
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#
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explain format=json select * from t0 A union select * from t0 B;
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EXPLAIN
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{
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"query_block": {
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"union_result": {
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"table_name": "<union1,2>",
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"access_type": "ALL",
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"query_specifications": [
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "A",
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"access_type": "ALL",
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"rows": 10,
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"filtered": 100
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}
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}
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},
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{
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"query_block": {
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"select_id": 2,
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"table": {
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"table_name": "B",
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"access_type": "ALL",
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"rows": 10,
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"filtered": 100
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}
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}
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}
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]
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}
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}
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}
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explain format=json select * from t0 A union all select * from t0 B;
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EXPLAIN
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{
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"query_block": {
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"union_result": {
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"table_name": "<union1,2>",
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"access_type": "ALL",
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"query_specifications": [
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "A",
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"access_type": "ALL",
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"rows": 10,
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"filtered": 100
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}
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}
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},
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{
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"query_block": {
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"select_id": 2,
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"table": {
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"table_name": "B",
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"access_type": "ALL",
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"rows": 10,
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"filtered": 100
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}
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}
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}
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]
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}
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}
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}
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#
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# Subqueries
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#
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create table t1 (a int, b int);
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insert into t1 select a,a from t0;
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explain format=json select a, a > (select max(b) from t1 where t1.b=t0.a) from t0;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "t0",
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"access_type": "ALL",
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"rows": 10,
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"filtered": 100
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},
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"subqueries": [
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{
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"query_block": {
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"select_id": 2,
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"table": {
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"table_name": "t1",
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"access_type": "ALL",
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"rows": 10,
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"filtered": 100,
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"attached_condition": "(t1.b = t0.a)"
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}
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}
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}
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]
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}
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}
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explain format=json
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select * from t0 where
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a > (select max(b) from t1 where t1.b=t0.a) or a < 3 ;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "t0",
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"access_type": "ALL",
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"rows": 10,
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"filtered": 100,
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"attached_condition": "((t0.a > (subquery#2)) or (t0.a < 3))"
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},
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"subqueries": [
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{
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"query_block": {
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"select_id": 2,
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"table": {
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"table_name": "t1",
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"access_type": "ALL",
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"rows": 10,
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"filtered": 100,
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"attached_condition": "(t1.b = t0.a)"
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}
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}
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}
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]
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}
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}
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drop table t1;
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#
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# Join buffering
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#
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create table t1 (a int, b int);
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insert into t1 select tbl1.a+10*tbl2.a, tbl1.a+10*tbl2.a from t0 tbl1, t0 tbl2;
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explain format=json
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select * from t1 tbl1, t1 tbl2 where tbl1.a=tbl2.a and tbl1.b < 3 and tbl2.b < 5;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "tbl1",
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"access_type": "ALL",
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"rows": 100,
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"filtered": 100,
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"attached_condition": "(tbl1.b < 3)"
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},
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"block-nl-join": {
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"table": {
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"table_name": "tbl2",
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"access_type": "ALL",
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"rows": 100,
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"filtered": 100,
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"attached_condition": "(tbl2.b < 5)"
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},
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"buffer_type": "flat",
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"buffer_size": "128Kb",
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"join_type": "BNL",
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"attached_condition": "(tbl2.a = tbl1.a)"
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}
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}
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}
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drop table t1;
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#
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# Single-table UPDATE/DELETE, INSERT
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#
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explain format=json delete from t0;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"message": "Deleting all rows"
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}
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}
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}
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explain format=json delete from t0 where 1 > 2;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"message": "Impossible WHERE"
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}
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}
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}
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explain format=json delete from t0 where a < 3;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"delete": 1,
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"table_name": "t0",
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"access_type": "ALL",
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"rows": 10,
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"attached_condition": "(t0.a < 3)"
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}
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}
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}
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explain format=json update t0 set a=3 where a in (2,3,4);
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"update": 1,
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"table_name": "t0",
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"access_type": "ALL",
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"rows": 10,
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"attached_condition": "(t0.a in (2,3,4))"
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}
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}
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}
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explain format=json insert into t0 values (1);
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "t0"
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}
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}
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}
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create table t1 like t0;
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explain format=json insert into t1 values ((select max(a) from t0));
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "t1"
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},
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"subqueries": [
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{
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"query_block": {
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"select_id": 2,
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"table": {
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"table_name": "t0",
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"access_type": "ALL",
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"rows": 10,
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"filtered": 100
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}
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}
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}
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]
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}
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}
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drop table t1;
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#
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# A derived table
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#
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create table t1 (a int, b int);
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insert into t1 select a,a from t0;
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explain format=json
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select * from (select a, count(*) as cnt from t1 group by a) as tbl
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where cnt>0;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"table_name": "<derived2>",
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"access_type": "ALL",
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|
"rows": 10,
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|
"filtered": 100,
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"attached_condition": "(tbl.cnt > 0)",
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"materialized": {
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|
"query_block": {
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|
"select_id": 2,
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|
"table": {
|
|
"table_name": "t1",
|
|
"access_type": "ALL",
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|
"rows": 10,
|
|
"filtered": 100
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}
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}
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|
}
|
|
}
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|
}
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}
|
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explain format=json
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select * from (select a, count(*) as cnt from t1 group by a) as tbl1, t1 as
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tbl2 where cnt=tbl2.a;
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EXPLAIN
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|
{
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|
"query_block": {
|
|
"select_id": 1,
|
|
"table": {
|
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"table_name": "tbl2",
|
|
"access_type": "ALL",
|
|
"rows": 10,
|
|
"filtered": 100,
|
|
"attached_condition": "(tbl2.a is not null)"
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},
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|
"table": {
|
|
"table_name": "<derived2>",
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|
"access_type": "ref",
|
|
"possible_keys": ["key0"],
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|
"key": "key0",
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|
"key_length": "8",
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|
"used_key_parts": ["cnt"],
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"ref": ["test.tbl2.a"],
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"rows": 2,
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|
"filtered": 100,
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"attached_condition": "(tbl1.cnt = tbl2.a)",
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|
"materialized": {
|
|
"query_block": {
|
|
"select_id": 2,
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|
"table": {
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|
"table_name": "t1",
|
|
"access_type": "ALL",
|
|
"rows": 10,
|
|
"filtered": 100
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|
}
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|
}
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|
}
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|
}
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|
}
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}
|
|
#
|
|
# Non-merged semi-join (aka JTBM)
|
|
#
|
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explain format=json
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select * from t1 where a in (select max(a) from t1 group by b);
|
|
EXPLAIN
|
|
{
|
|
"query_block": {
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|
"select_id": 1,
|
|
"table": {
|
|
"table_name": "t1",
|
|
"access_type": "ALL",
|
|
"rows": 10,
|
|
"filtered": 100,
|
|
"attached_condition": "(t1.a is not null)"
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},
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|
"table": {
|
|
"table_name": "<subquery2>",
|
|
"access_type": "eq_ref",
|
|
"possible_keys": ["distinct_key"],
|
|
"key": "distinct_key",
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|
"key_length": "4",
|
|
"used_key_parts": ["max(a)"],
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|
"ref": ["test.t1.a"],
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|
"rows": 1,
|
|
"filtered": 100,
|
|
"materialized": {
|
|
"unique": 1,
|
|
"query_block": {
|
|
"select_id": 2,
|
|
"table": {
|
|
"table_name": "t1",
|
|
"access_type": "ALL",
|
|
"rows": 10,
|
|
"filtered": 100
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
#
|
|
# Semi-join Materialization
|
|
#
|
|
create table t2 like t1;
|
|
insert into t2 select * from t1;
|
|
explain format=json
|
|
select * from t1,t2 where t1.a in ( select a from t0);
|
|
EXPLAIN
|
|
{
|
|
"query_block": {
|
|
"select_id": 1,
|
|
"const_condition": "1",
|
|
"table": {
|
|
"table_name": "t1",
|
|
"access_type": "ALL",
|
|
"rows": 10,
|
|
"filtered": 100
|
|
},
|
|
"table": {
|
|
"table_name": "<subquery2>",
|
|
"access_type": "eq_ref",
|
|
"possible_keys": ["distinct_key"],
|
|
"key": "distinct_key",
|
|
"key_length": "4",
|
|
"used_key_parts": ["a"],
|
|
"ref": ["func"],
|
|
"rows": 1,
|
|
"filtered": 100,
|
|
"materialized": {
|
|
"unique": 1,
|
|
"query_block": {
|
|
"select_id": 2,
|
|
"table": {
|
|
"table_name": "t0",
|
|
"access_type": "ALL",
|
|
"rows": 10,
|
|
"filtered": 100
|
|
}
|
|
}
|
|
}
|
|
},
|
|
"block-nl-join": {
|
|
"table": {
|
|
"table_name": "t2",
|
|
"access_type": "ALL",
|
|
"rows": 10,
|
|
"filtered": 100
|
|
},
|
|
"buffer_type": "flat",
|
|
"buffer_size": "128Kb",
|
|
"join_type": "BNL"
|
|
}
|
|
}
|
|
}
|
|
#
|
|
# First-Match
|
|
#
|
|
explain
|
|
select * from t2 where t2.a in ( select a from t1 where t1.b=t2.b);
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 PRIMARY t2 ALL NULL NULL NULL NULL 10
|
|
1 PRIMARY t1 ALL NULL NULL NULL NULL 10 Using where; FirstMatch(t2); Using join buffer (flat, BNL join)
|
|
explain format=json
|
|
select * from t2 where t2.a in ( select a from t1 where t1.b=t2.b);
|
|
EXPLAIN
|
|
{
|
|
"query_block": {
|
|
"select_id": 1,
|
|
"table": {
|
|
"table_name": "t2",
|
|
"access_type": "ALL",
|
|
"rows": 10,
|
|
"filtered": 100
|
|
},
|
|
"block-nl-join": {
|
|
"table": {
|
|
"table_name": "t1",
|
|
"access_type": "ALL",
|
|
"rows": 10,
|
|
"filtered": 100,
|
|
"first_match": "t2"
|
|
},
|
|
"buffer_type": "flat",
|
|
"buffer_size": "128Kb",
|
|
"join_type": "BNL",
|
|
"attached_condition": "((t1.b = t2.b) and (t1.a = t2.a))"
|
|
}
|
|
}
|
|
}
|
|
#
|
|
# Duplicate Weedout
|
|
#
|
|
set @tmp= @@optimizer_switch;
|
|
set optimizer_switch='firstmatch=off';
|
|
explain
|
|
select * from t2 where t2.a in ( select a from t1 where t1.b=t2.b);
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 PRIMARY t2 ALL NULL NULL NULL NULL 10
|
|
1 PRIMARY t1 ALL NULL NULL NULL NULL 10 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join)
|
|
explain format=json
|
|
select * from t2 where t2.a in ( select a from t1 where t1.b=t2.b);
|
|
EXPLAIN
|
|
{
|
|
"query_block": {
|
|
"select_id": 1,
|
|
"table": {
|
|
"table_name": "t2",
|
|
"access_type": "ALL",
|
|
"rows": 10,
|
|
"filtered": 100
|
|
},
|
|
"duplicates_removal": {
|
|
"block-nl-join": {
|
|
"table": {
|
|
"table_name": "t1",
|
|
"access_type": "ALL",
|
|
"rows": 10,
|
|
"filtered": 100
|
|
},
|
|
"buffer_type": "flat",
|
|
"buffer_size": "128Kb",
|
|
"join_type": "BNL",
|
|
"attached_condition": "((t1.b = t2.b) and (t1.a = t2.a))"
|
|
}
|
|
}
|
|
}
|
|
}
|
|
set optimizer_switch=@tmp;
|
|
drop table t1,t2;
|
|
#
|
|
# MRR for range access (no BKA, just MRR)
|
|
#
|
|
create table t1 (a int, b int, key(a));
|
|
insert into t1 select tbl1.a+10*tbl2.a, 12345 from t0 tbl1, t0 tbl2;
|
|
set @tmp= @@optimizer_switch;
|
|
set optimizer_switch='mrr=on,mrr_sort_keys=on';
|
|
explain format=json select * from t1 where a < 3;
|
|
EXPLAIN
|
|
{
|
|
"query_block": {
|
|
"select_id": 1,
|
|
"table": {
|
|
"table_name": "t1",
|
|
"access_type": "range",
|
|
"possible_keys": ["a"],
|
|
"key": "a",
|
|
"key_length": "5",
|
|
"used_key_parts": ["a"],
|
|
"rows": 1,
|
|
"filtered": 100,
|
|
"index_condition": "(t1.a < 3)",
|
|
"mrr_type": "Rowid-ordered scan"
|
|
}
|
|
}
|
|
}
|
|
# 'Range checked for each record'
|
|
set optimizer_switch=@tmp;
|
|
explain format=json
|
|
select * from t1 tbl1, t1 tbl2 where tbl2.a < tbl1.b;
|
|
EXPLAIN
|
|
{
|
|
"query_block": {
|
|
"select_id": 1,
|
|
"table": {
|
|
"table_name": "tbl1",
|
|
"access_type": "ALL",
|
|
"rows": 100,
|
|
"filtered": 100
|
|
},
|
|
"range-checked-for-each-record": {
|
|
"keys": ["a"],
|
|
"table": {
|
|
"table_name": "tbl2",
|
|
"access_type": "ALL",
|
|
"possible_keys": ["a"],
|
|
"rows": 100,
|
|
"filtered": 100
|
|
}
|
|
}
|
|
}
|
|
}
|
|
drop table t1;
|
|
drop table t0;
|
|
#
|
|
# MDEV-7265: "Full scan on NULL key", the join case
|
|
#
|
|
CREATE TABLE t1 (a INT, KEY(a));
|
|
INSERT INTO t1 VALUES (1),(2);
|
|
CREATE TABLE t2 (b INT);
|
|
INSERT INTO t2 VALUES (3),(4);
|
|
EXPLAIN FORMAT=JSON SELECT * FROM t1 AS outer_t1 WHERE a <> ALL ( SELECT a FROM t1, t2 WHERE b <> outer_t1.a );
|
|
EXPLAIN
|
|
{
|
|
"query_block": {
|
|
"select_id": 1,
|
|
"table": {
|
|
"table_name": "outer_t1",
|
|
"access_type": "index",
|
|
"key": "a",
|
|
"key_length": "5",
|
|
"used_key_parts": ["a"],
|
|
"rows": 2,
|
|
"filtered": 100,
|
|
"attached_condition": "(not(<in_optimizer>(outer_t1.a,<exists>(subquery#2))))",
|
|
"using_index": true
|
|
},
|
|
"subqueries": [
|
|
{
|
|
"query_block": {
|
|
"select_id": 2,
|
|
"full-scan-on-null_key": {
|
|
"table": {
|
|
"table_name": "t1",
|
|
"access_type": "ref_or_null",
|
|
"possible_keys": ["a"],
|
|
"key": "a",
|
|
"key_length": "5",
|
|
"used_key_parts": ["a"],
|
|
"ref": ["func"],
|
|
"rows": 2,
|
|
"filtered": 100,
|
|
"attached_condition": "trigcond(((<cache>(outer_t1.a) = t1.a) or isnull(t1.a)))",
|
|
"using_index": true
|
|
}
|
|
},
|
|
"block-nl-join": {
|
|
"table": {
|
|
"table_name": "t2",
|
|
"access_type": "ALL",
|
|
"rows": 2,
|
|
"filtered": 100
|
|
},
|
|
"buffer_type": "flat",
|
|
"buffer_size": "128Kb",
|
|
"join_type": "BNL",
|
|
"attached_condition": "((t2.b <> outer_t1.a) and trigcond(((<cache>(outer_t1.a) = t1.a) or isnull(t1.a))))"
|
|
}
|
|
}
|
|
}
|
|
]
|
|
}
|
|
}
|
|
DROP TABLE t1,t2;
|
|
#
|
|
# Join's constant expression
|
|
#
|
|
create table t0(a int);
|
|
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
|
|
create table t1(a int, b int);
|
|
insert into t1 select tbl1.a+10*tbl2.a, 1234 from t0 tbl1, t0 tbl2;
|
|
explain format=json
|
|
select * from t0
|
|
where
|
|
20000 > all (select max(tbl1.a + tbl2.a)
|
|
from t1 tbl1, t1 tbl2 where tbl1.b=tbl2.b);
|
|
EXPLAIN
|
|
{
|
|
"query_block": {
|
|
"select_id": 1,
|
|
"const_condition": "<not>(<in_optimizer>(20000,(<max>(subquery#2) >= 20000)))",
|
|
"table": {
|
|
"table_name": "t0",
|
|
"access_type": "ALL",
|
|
"rows": 10,
|
|
"filtered": 100
|
|
},
|
|
"subqueries": [
|
|
{
|
|
"query_block": {
|
|
"select_id": 2,
|
|
"table": {
|
|
"table_name": "tbl1",
|
|
"access_type": "ALL",
|
|
"rows": 100,
|
|
"filtered": 100
|
|
},
|
|
"block-nl-join": {
|
|
"table": {
|
|
"table_name": "tbl2",
|
|
"access_type": "ALL",
|
|
"rows": 100,
|
|
"filtered": 100
|
|
},
|
|
"buffer_type": "flat",
|
|
"buffer_size": "128Kb",
|
|
"join_type": "BNL",
|
|
"attached_condition": "(tbl2.b = tbl1.b)"
|
|
}
|
|
}
|
|
}
|
|
]
|
|
}
|
|
}
|
|
drop table t1;
|
|
drop table t0;
|
|
#
|
|
# MDEV-7264: Assertion `0' failed in subselect_engine::get_identifier() on EXPLAIN JSON
|
|
#
|
|
CREATE TABLE t1 (a INT);
|
|
INSERT INTO t1 VALUES (1),(2);
|
|
CREATE TABLE t2 (b INT);
|
|
INSERT INTO t2 VALUES (3),(4);
|
|
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE a <> ALL ( SELECT b FROM t2 );
|
|
EXPLAIN
|
|
{
|
|
"query_block": {
|
|
"select_id": 1,
|
|
"table": {
|
|
"table_name": "t1",
|
|
"access_type": "ALL",
|
|
"rows": 2,
|
|
"filtered": 100,
|
|
"attached_condition": "(not(<in_optimizer>(t1.a,t1.a in (subquery#2))))"
|
|
},
|
|
"subqueries": [
|
|
{
|
|
"query_block": {
|
|
"select_id": 2,
|
|
"table": {
|
|
"table_name": "t2",
|
|
"access_type": "ALL",
|
|
"rows": 2,
|
|
"filtered": 100
|
|
}
|
|
}
|
|
}
|
|
]
|
|
}
|
|
}
|
|
DROP TABLE t1, t2;
|
|
#
|
|
# MDEV-7927: Server crashes in in Time_and_counter_tracker::incr_loops
|
|
#
|
|
CREATE TABLE t1 (i INT);
|
|
INSERT INTO t1 VALUES (1),(2);
|
|
EXPLAIN SELECT * FROM t1 WHERE 3 IN ( SELECT 4 UNION SELECT 5 );
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
|
|
2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL No tables used
|
|
3 UNION NULL NULL NULL NULL NULL NULL NULL No tables used
|
|
NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
|
|
DROP TABLE t1;
|
|
#
|
|
# MDEV-7860: EXPLAIN FORMAT=JSON crashes for loose scan query
|
|
#
|
|
create table t2(a int);
|
|
insert into t2 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
|
|
create table t1 (a int, b int, c int, d int, key(a,b,c));
|
|
insert into t1 select A.a, B.a, C.a, D.a from t2 A, t2 B, t2 C, t2 D;
|
|
explain select count(distinct b) from t1 group by a;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 SIMPLE t1 range NULL a 10 NULL 101 Using index for group-by
|
|
explain format=json select count(distinct b) from t1 group by a;
|
|
EXPLAIN
|
|
{
|
|
"query_block": {
|
|
"select_id": 1,
|
|
"table": {
|
|
"table_name": "t1",
|
|
"access_type": "range",
|
|
"key": "a",
|
|
"key_length": "10",
|
|
"used_key_parts": ["a", "b"],
|
|
"rows": 101,
|
|
"filtered": 100,
|
|
"using_index_for_group_by": true
|
|
}
|
|
}
|
|
}
|
|
analyze format=json select count(distinct b) from t1 group by a;
|
|
ANALYZE
|
|
{
|
|
"query_block": {
|
|
"select_id": 1,
|
|
"r_loops": 1,
|
|
"r_total_time_ms": "REPLACED",
|
|
"table": {
|
|
"table_name": "t1",
|
|
"access_type": "range",
|
|
"key": "a",
|
|
"key_length": "10",
|
|
"used_key_parts": ["a", "b"],
|
|
"r_loops": 1,
|
|
"rows": 101,
|
|
"r_rows": 100,
|
|
"r_total_time_ms": "REPLACED",
|
|
"filtered": 100,
|
|
"r_filtered": 100,
|
|
"using_index_for_group_by": true
|
|
}
|
|
}
|
|
}
|
|
drop table t1,t2;
|
|
#
|
|
# Try both variants of LooseScan (data/queries borrowed from group_min_max.test)
|
|
#
|
|
create table t1 (
|
|
a1 char(64), a2 char(64), b char(16), c char(16) not null, d char(16), dummy char(248) default ' '
|
|
);
|
|
insert into t1 (a1, a2, b, c, d) values
|
|
('a','a','a','a111','xy1'),('a','a','a','b111','xy2'),('a','a','a','c111','xy3'),('a','a','a','d111','xy4'),
|
|
('a','a','b','e112','xy1'),('a','a','b','f112','xy2'),('a','a','b','g112','xy3'),('a','a','b','h112','xy4'),
|
|
('a','b','a','i121','xy1'),('a','b','a','j121','xy2'),('a','b','a','k121','xy3'),('a','b','a','l121','xy4'),
|
|
('a','b','b','m122','xy1'),('a','b','b','n122','xy2'),('a','b','b','o122','xy3'),('a','b','b','p122','xy4'),
|
|
('b','a','a','a211','xy1'),('b','a','a','b211','xy2'),('b','a','a','c211','xy3'),('b','a','a','d211','xy4'),
|
|
('b','a','b','e212','xy1'),('b','a','b','f212','xy2'),('b','a','b','g212','xy3'),('b','a','b','h212','xy4'),
|
|
('b','b','a','i221','xy1'),('b','b','a','j221','xy2'),('b','b','a','k221','xy3'),('b','b','a','l221','xy4'),
|
|
('b','b','b','m222','xy1'),('b','b','b','n222','xy2'),('b','b','b','o222','xy3'),('b','b','b','p222','xy4'),
|
|
('c','a','a','a311','xy1'),('c','a','a','b311','xy2'),('c','a','a','c311','xy3'),('c','a','a','d311','xy4'),
|
|
('c','a','b','e312','xy1'),('c','a','b','f312','xy2'),('c','a','b','g312','xy3'),('c','a','b','h312','xy4'),
|
|
('c','b','a','i321','xy1'),('c','b','a','j321','xy2'),('c','b','a','k321','xy3'),('c','b','a','l321','xy4'),
|
|
('c','b','b','m322','xy1'),('c','b','b','n322','xy2'),('c','b','b','o322','xy3'),('c','b','b','p322','xy4'),
|
|
('d','a','a','a411','xy1'),('d','a','a','b411','xy2'),('d','a','a','c411','xy3'),('d','a','a','d411','xy4'),
|
|
('d','a','b','e412','xy1'),('d','a','b','f412','xy2'),('d','a','b','g412','xy3'),('d','a','b','h412','xy4'),
|
|
('d','b','a','i421','xy1'),('d','b','a','j421','xy2'),('d','b','a','k421','xy3'),('d','b','a','l421','xy4'),
|
|
('d','b','b','m422','xy1'),('d','b','b','n422','xy2'),('d','b','b','o422','xy3'),('d','b','b','p422','xy4'),
|
|
('a','a','a','a111','xy1'),('a','a','a','b111','xy2'),('a','a','a','c111','xy3'),('a','a','a','d111','xy4'),
|
|
('a','a','b','e112','xy1'),('a','a','b','f112','xy2'),('a','a','b','g112','xy3'),('a','a','b','h112','xy4'),
|
|
('a','b','a','i121','xy1'),('a','b','a','j121','xy2'),('a','b','a','k121','xy3'),('a','b','a','l121','xy4'),
|
|
('a','b','b','m122','xy1'),('a','b','b','n122','xy2'),('a','b','b','o122','xy3'),('a','b','b','p122','xy4'),
|
|
('b','a','a','a211','xy1'),('b','a','a','b211','xy2'),('b','a','a','c211','xy3'),('b','a','a','d211','xy4'),
|
|
('b','a','b','e212','xy1'),('b','a','b','f212','xy2'),('b','a','b','g212','xy3'),('b','a','b','h212','xy4'),
|
|
('b','b','a','i221','xy1'),('b','b','a','j221','xy2'),('b','b','a','k221','xy3'),('b','b','a','l221','xy4'),
|
|
('b','b','b','m222','xy1'),('b','b','b','n222','xy2'),('b','b','b','o222','xy3'),('b','b','b','p222','xy4'),
|
|
('c','a','a','a311','xy1'),('c','a','a','b311','xy2'),('c','a','a','c311','xy3'),('c','a','a','d311','xy4'),
|
|
('c','a','b','e312','xy1'),('c','a','b','f312','xy2'),('c','a','b','g312','xy3'),('c','a','b','h312','xy4'),
|
|
('c','b','a','i321','xy1'),('c','b','a','j321','xy2'),('c','b','a','k321','xy3'),('c','b','a','l321','xy4'),
|
|
('c','b','b','m322','xy1'),('c','b','b','n322','xy2'),('c','b','b','o322','xy3'),('c','b','b','p322','xy4'),
|
|
('d','a','a','a411','xy1'),('d','a','a','b411','xy2'),('d','a','a','c411','xy3'),('d','a','a','d411','xy4'),
|
|
('d','a','b','e412','xy1'),('d','a','b','f412','xy2'),('d','a','b','g412','xy3'),('d','a','b','h412','xy4'),
|
|
('d','b','a','i421','xy1'),('d','b','a','j421','xy2'),('d','b','a','k421','xy3'),('d','b','a','l421','xy4'),
|
|
('d','b','b','m422','xy1'),('d','b','b','n422','xy2'),('d','b','b','o422','xy3'),('d','b','b','p422','xy4');
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create index idx_t1_0 on t1 (a1);
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create index idx_t1_1 on t1 (a1,a2,b,c);
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create index idx_t1_2 on t1 (a1,a2,b);
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analyze table t1;
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Table Op Msg_type Msg_text
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|
test.t1 analyze status Table is already up to date
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|
explain select count(distinct a1,a2,b) from t1 where (a2 >= 'b') and (b = 'a');
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 SIMPLE t1 range NULL idx_t1_1 147 NULL 17 Using where; Using index for group-by
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|
explain select count(distinct a1,a2,b,c) from t1 where (a2 >= 'b') and (b = 'a') and (c = 'i121');
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 SIMPLE t1 range NULL idx_t1_1 163 NULL 65 Using where; Using index for group-by (scanning)
|
|
explain format=json select count(distinct a1,a2,b) from t1 where (a2 >= 'b') and (b = 'a');
|
|
EXPLAIN
|
|
{
|
|
"query_block": {
|
|
"select_id": 1,
|
|
"table": {
|
|
"table_name": "t1",
|
|
"access_type": "range",
|
|
"key": "idx_t1_1",
|
|
"key_length": "147",
|
|
"used_key_parts": ["a1", "a2", "b"],
|
|
"rows": 17,
|
|
"filtered": 100,
|
|
"attached_condition": "((t1.b = 'a') and (t1.a2 >= 'b'))",
|
|
"using_index_for_group_by": true
|
|
}
|
|
}
|
|
}
|
|
explain format=json select count(distinct a1,a2,b,c) from t1 where (a2 >= 'b') and (b = 'a') and (c = 'i121');
|
|
EXPLAIN
|
|
{
|
|
"query_block": {
|
|
"select_id": 1,
|
|
"table": {
|
|
"table_name": "t1",
|
|
"access_type": "range",
|
|
"key": "idx_t1_1",
|
|
"key_length": "163",
|
|
"used_key_parts": ["a1", "a2", "b", "c"],
|
|
"rows": 65,
|
|
"filtered": 100,
|
|
"attached_condition": "((t1.b = 'a') and (t1.c = 'i121') and (t1.a2 >= 'b'))",
|
|
"using_index_for_group_by": "scanning"
|
|
}
|
|
}
|
|
}
|
|
drop table t1;
|