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EXPLAIN FORMAT=JSON: Full scan on NULL key (join case)

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Sergei Petrunia
2014-12-06 03:11:03 +03:00
parent a80a797686
commit 5ee1c25fa8
5 changed files with 85 additions and 0 deletions
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59
mysql-test/r/explain_json.result
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@ -719,3 +719,62 @@ EXPLAIN
}
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",
"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;