tidb/executor/explain_test.go

// Copyright 2016 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.

package executor_test

import (
	. "github.com/pingcap/check"
	"github.com/pingcap/tidb/util/testkit"
	"github.com/pingcap/tidb/util/testleak"
)

func (s *testSuite) TestExplain(c *C) {
	defer func() {
		s.cleanEnv(c)
		testleak.AfterTest(c)()
	}()
	tk := testkit.NewTestKit(c, s.store)
	tk.MustExec("use test")
	tk.MustExec("drop table if exists t1, t2")
	tk.MustExec("create table t1 (c1 int primary key, c2 int, index c2 (c2))")
	tk.MustExec("create table t2 (c1 int unique, c2 int)")

	cases := []struct {
		sql       string
		ids       []string
		parentIds []string
		result    []string
	}{
		{
			"select * from t1",
			[]string{
				"TableScan_3",
			},
			[]string{
				"",
			},
			[]string{
				`{
    "db": "test",
    "table": "t1",
    "desc": false,
    "keep order": false,
    "push down info": {
        "limit": 0,
        "access conditions": null,
        "filter conditions": null
    }
}`,
			},
		},
		{
			"select * from t1 order by c2",
			[]string{
				"IndexScan_5",
			},
			[]string{
				"",
			},
			[]string{
				`{
    "db": "test",
    "table": "t1",
    "index": "c2",
    "ranges": "[[\u003cnil\u003e,+inf]]",
    "desc": false,
    "out of order": false,
    "double read": false,
    "push down info": {
        "limit": 0,
        "access conditions": null,
        "filter conditions": null
    }
}`,
			},
		},
		{
			"select * from t2 order by c2",
			[]string{
				"TableScan_6", "Sort_3",
			},
			[]string{
				"Sort_3", "",
			},
			[]string{
				`{
    "db": "test",
    "table": "t2",
    "desc": false,
    "keep order": false,
    "push down info": {
        "limit": 0,
        "access conditions": null,
        "filter conditions": null
    }
}`,
				`{
    "exprs": [
        {
            "Expr": "t2.c2",
            "Desc": false
        }
    ],
    "limit": null,
    "child": "TableScan_6"
}`,
			},
		},
		{
			"select * from t1 where t1.c1 > 0",
			[]string{
				"TableScan_4",
			},
			[]string{
				"",
			},
			[]string{`{
    "db": "test",
    "table": "t1",
    "desc": false,
    "keep order": false,
    "push down info": {
        "limit": 0,
        "access conditions": [
            "gt(test.t1.c1, 0)"
        ],
        "filter conditions": null
    }
}`,
			},
		},
		{
			"select * from t1 where t1.c2 = 1",
			[]string{
				"IndexScan_5",
			},
			[]string{
				"",
			},
			[]string{`{
    "db": "test",
    "table": "t1",
    "index": "c2",
    "ranges": "[[1,1]]",
    "desc": false,
    "out of order": true,
    "double read": false,
    "push down info": {
        "limit": 0,
        "access conditions": [
            "eq(test.t1.c2, 1)"
        ],
        "filter conditions": null
    }
}`,
			},
		},
		{
			"select * from t1 left join t2 on t1.c2 = t2.c1 where t1.c1 > 1",
			[]string{
				"TableScan_8", "TableScan_10", "HashLeftJoin_7",
			},
			[]string{
				"HashLeftJoin_7", "HashLeftJoin_7", "",
			},
			[]string{
				`{
    "db": "test",
    "table": "t1",
    "desc": false,
    "keep order": false,
    "push down info": {
        "limit": 0,
        "access conditions": [
            "gt(test.t1.c1, 1)"
        ],
        "filter conditions": null
    }
}`,
				`{
    "db": "test",
    "table": "t2",
    "desc": false,
    "keep order": false,
    "push down info": {
        "limit": 0,
        "access conditions": null,
        "filter conditions": null
    }
}`,
				`{
    "eqCond": [
        "eq(test.t1.c2, test.t2.c1)"
    ],
    "leftCond": null,
    "rightCond": null,
    "otherCond": null,
    "leftPlan": "TableScan_8",
    "rightPlan": "TableScan_10"
}`,
			},
		},
		{
			"update t1 set t1.c2 = 2 where t1.c1 = 1",
			[]string{
				"TableScan_4", "Update_3",
			},
			[]string{
				"Update_3", "",
			},
			[]string{`{
    "db": "test",
    "table": "t1",
    "desc": false,
    "keep order": false,
    "push down info": {
        "limit": 0,
        "access conditions": [
            "eq(test.t1.c1, 1)"
        ],
        "filter conditions": null
    }
}`,
				`{
    "children": [
        "TableScan_4"
    ]
}`,
			},
		},
		{
			"delete from t1 where t1.c2 = 1",
			[]string{
				"IndexScan_5", "Delete_3",
			},
			[]string{
				"Delete_3", "",
			},
			[]string{`{
    "db": "test",
    "table": "t1",
    "index": "c2",
    "ranges": "[[1,1]]",
    "desc": false,
    "out of order": true,
    "double read": false,
    "push down info": {
        "limit": 0,
        "access conditions": [
            "eq(test.t1.c2, 1)"
        ],
        "filter conditions": null
    }
}`,
				`{
    "children": [
        "IndexScan_5"
    ]
}`,
			},
		},
		{
			"select count(b.c2) from t1 a, t2 b where a.c1 = b.c2 group by a.c1",
			[]string{
				"TableScan_10", "TableScan_12", "HashAgg_14", "HashLeftJoin_9", "HashAgg_17",
			},
			[]string{
				"HashLeftJoin_9", "HashAgg_14", "HashLeftJoin_9", "HashAgg_17", "",
			},
			[]string{`{
    "db": "test",
    "table": "t1",
    "desc": false,
    "keep order": false,
    "push down info": {
        "limit": 0,
        "access conditions": null,
        "filter conditions": null
    }
}`,
				`{
    "db": "test",
    "table": "t2",
    "desc": false,
    "keep order": false,
    "push down info": {
        "limit": 0,
        "aggregated push down": true,
        "gby items": [
            "b.c2"
        ],
        "agg funcs": [
            "count(b.c2)",
            "firstrow(b.c2)"
        ],
        "access conditions": null,
        "filter conditions": null
    }
}`,
				`{
    "AggFuncs": [
        "count([b.c2])",
        "firstrow([b.c2])"
    ],
    "GroupByItems": [
        "[b.c2]"
    ],
    "child": "TableScan_12"
}`,
				`{
    "eqCond": [
        "eq(a.c1, b.c2)"
    ],
    "leftCond": null,
    "rightCond": null,
    "otherCond": null,
    "leftPlan": "TableScan_10",
    "rightPlan": "HashAgg_14"
}`,
				`{
    "AggFuncs": [
        "count(join_agg_0)"
    ],
    "GroupByItems": [
        "a.c1"
    ],
    "child": "HashLeftJoin_9"
}`,
			},
		},
	}
	for _, ca := range cases {
		result := tk.MustQuery("explain " + ca.sql)
		var resultList []string
		for i := range ca.ids {
			resultList = append(resultList, ca.ids[i]+" "+ca.result[i]+" "+ca.parentIds[i])
		}
		result.Check(testkit.Rows(resultList...))
	}
}