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EXPLAIN FORMAT=JSON: support derived tables

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Sergei Petrunia
2014-11-28 22:23:29 +03:00
parent 3a5e080d4d
commit 2ac3b39e68
6 changed files with 141 additions and 9 deletions
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71
mysql-test/r/explain_json.result
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@ -393,4 +393,75 @@ EXPLAIN
}
}
}
#
# A derived table
#
create table t1 (a int, b int);
insert into t1 select a,a from t0;
explain format=json
select * from (select a, count(*) as cnt from t1 group by a) as tbl
where cnt>0;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "<derived2>",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(tbl.cnt > 0)",
"materialized": {
"query_block": {
"select_id": 2,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
}
}
}
}
explain format=json
select * from (select a, count(*) as cnt from t1 group by a) as tbl1, t1 as
tbl2 where cnt=tbl2.a;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "tbl2",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(tbl2.a is not null)"
},
"table": {
"table_name": "<derived2>",
"access_type": "ref",
"possible_keys": ["key0"],
"key": "key0",
"key_length": "8",
"used_key_parts": ["cnt"],
"ref": ["test.tbl2.a"],
"rows": 2,
"filtered": 100,
"attached_condition": "(tbl1.cnt = tbl2.a)",
"materialized": {
"query_block": {
"select_id": 2,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
}
}
}
}
drop table t0;