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support _tidb_rowid for table scan range (#8047) #9059

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Jan 15, 2019
Merged

support _tidb_rowid for table scan range (#8047) #9059

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25 changes: 24 additions & 1 deletion cmd/explaintest/r/explain_easy.result
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Original file line number Diff line number Diff line change
Expand Up @@ -390,7 +390,7 @@ Sort_13 2.00 root a:asc
└─HashAgg_26 1.00 root group by:a, funcs:firstrow(a), firstrow(a)
└─Projection_27 1.00 root 1
└─TableDual_28 1.00 root rows:1
explain SELECT 0 AS a FROM dual UNION (SELECT 1 AS a FROM dual ORDER BY a)
explain SELECT 0 AS a FROM dual UNION (SELECT 1 AS a FROM dual ORDER BY a);
id count task operator info
HashAgg_15 2.00 root group by:a, funcs:firstrow(join_agg_0)
└─Union_16 2.00 root
Expand All @@ -400,3 +400,26 @@ HashAgg_15 2.00 root group by:a, funcs:firstrow(join_agg_0)
└─StreamAgg_26 1.00 root group by:a, funcs:firstrow(a), firstrow(a)
└─Projection_31 1.00 root 1
└─TableDual_32 1.00 root rows:1
drop table if exists t;
create table t(a int);
explain select * from t where _tidb_rowid = 0;
id count task operator info
Projection_4 8000.00 root test.t.a
└─TableReader_6 10000.00 root data:TableScan_5
└─TableScan_5 10000.00 cop table:t, range:[0,0], keep order:false, stats:pseudo
explain select * from t where _tidb_rowid > 0;
id count task operator info
Projection_4 8000.00 root test.t.a
└─TableReader_6 10000.00 root data:TableScan_5
└─TableScan_5 10000.00 cop table:t, range:(0,+inf], keep order:false, stats:pseudo
explain select a, _tidb_rowid from t where a > 0;
id count task operator info
TableReader_7 3333.33 root data:Selection_6
└─Selection_6 3333.33 cop gt(test.t.a, 0)
└─TableScan_5 10000.00 cop table:t, range:[-inf,+inf], keep order:false, stats:pseudo
explain select * from t where _tidb_rowid > 0 and a > 0;
id count task operator info
Projection_4 2666.67 root test.t.a
└─TableReader_7 2666.67 root data:Selection_6
└─Selection_6 2666.67 cop gt(test.t.a, 0)
└─TableScan_5 3333.33 cop table:t, range:(0,+inf], keep order:false, stats:pseudo
9 changes: 8 additions & 1 deletion cmd/explaintest/t/explain_easy.test
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Expand Up @@ -82,4 +82,11 @@ explain select * from ta where a = 1;
rollback;

explain SELECT 0 AS a FROM dual UNION SELECT 1 AS a FROM dual ORDER BY a;
explain SELECT 0 AS a FROM dual UNION (SELECT 1 AS a FROM dual ORDER BY a)
explain SELECT 0 AS a FROM dual UNION (SELECT 1 AS a FROM dual ORDER BY a);

drop table if exists t;
create table t(a int);
explain select * from t where _tidb_rowid = 0;
explain select * from t where _tidb_rowid > 0;
explain select a, _tidb_rowid from t where a > 0;
explain select * from t where _tidb_rowid > 0 and a > 0;
6 changes: 5 additions & 1 deletion planner/core/logical_plans.go
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Expand Up @@ -340,7 +340,10 @@ func (ds *DataSource) deriveTablePathStats(path *accessPath) (bool, error) {
path.countAfterAccess = float64(ds.statisticTable.Count)
path.tableFilters = ds.pushedDownConds
var pkCol *expression.Column
if ds.tableInfo.PKIsHandle {
columnLen := len(ds.schema.Columns)
if columnLen > 0 && ds.schema.Columns[columnLen-1].ID == model.ExtraHandleID {
pkCol = ds.schema.Columns[columnLen-1]
} else if ds.tableInfo.PKIsHandle {
if pkColInfo := ds.tableInfo.GetPkColInfo(); pkColInfo != nil {
pkCol = expression.ColInfo2Col(ds.schema.Columns, pkColInfo)
}
Expand All @@ -349,6 +352,7 @@ func (ds *DataSource) deriveTablePathStats(path *accessPath) (bool, error) {
path.ranges = ranger.FullIntRange(false)
return false, nil
}

path.ranges = ranger.FullIntRange(mysql.HasUnsignedFlag(pkCol.RetType.Flag))
if len(ds.pushedDownConds) == 0 {
return false, nil
Expand Down