planner: don't prune sleep function in LogicalProjection (#11927) (#1…

…1953)
pingcap · Sep 10, 2019 · 652c2db · 652c2db
1 parent 78ed282
commit 652c2db
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Showing 3 changed files with 14 additions and 6 deletions.
diff --git a/cmd/explaintest/r/select.result b/cmd/explaintest/r/select.result
@@ -430,3 +430,8 @@ Projection_7	10000.00	root	6_aux_0
   │ └─TableScan_9	10000.00	cop	table:t1, range:[-inf,+inf], keep order:false, stats:pseudo
   └─TableReader_12	10000.00	root	data:TableScan_11
     └─TableScan_11	10000.00	cop	table:t2, range:[-inf,+inf], keep order:false, stats:pseudo
+explain select 1 from (select sleep(1)) t;
+id	count	task	operator info
+Projection_4	1.00	root	1
+└─Projection_5	1.00	root	sleep(1)
+  └─TableDual_6	1.00	root	rows:1
diff --git a/cmd/explaintest/t/select.test b/cmd/explaintest/t/select.test
@@ -201,3 +201,6 @@ explain select a in (select a+b from t t2 where t2.b = t1.b) from t t1;
 drop table t;
 create table t(a int not null, b int);
 explain select a in (select a from t t2 where t2.b = t1.b) from t t1;
+
+# test sleep in subquery
+explain select 1 from (select sleep(1)) t;
diff --git a/planner/core/rule_column_pruning.go b/planner/core/rule_column_pruning.go
@@ -53,25 +53,25 @@ func getUsedList(usedCols []*expression.Column, schema *expression.Schema) ([]bo
 	return used, nil
 }
 
-// exprHasSetVar checks if the expression has SetVar function.
-func exprHasSetVar(expr expression.Expression) bool {
+// exprHasSetVarOrSleep checks if the expression has SetVar function or Sleep function.
+func exprHasSetVarOrSleep(expr expression.Expression) bool {
 	scalaFunc, isScalaFunc := expr.(*expression.ScalarFunction)
 	if !isScalaFunc {
 		return false
 	}
-	if scalaFunc.FuncName.L == ast.SetVar {
+	if scalaFunc.FuncName.L == ast.SetVar || scalaFunc.FuncName.L == ast.Sleep {
 		return true
 	}
 	for _, arg := range scalaFunc.GetArgs() {
-		if exprHasSetVar(arg) {
+		if exprHasSetVarOrSleep(arg) {
 			return true
 		}
 	}
 	return false
 }
 
 // PruneColumns implements LogicalPlan interface.
-// If any expression has SetVar functions, we do not prune it.
+// If any expression has SetVar function or Sleep function, we do not prune it.
 func (p *LogicalProjection) PruneColumns(parentUsedCols []*expression.Column) error {
 	child := p.children[0]
 	used, err := getUsedList(parentUsedCols, p.schema)
@@ -80,7 +80,7 @@ func (p *LogicalProjection) PruneColumns(parentUsedCols []*expression.Column) er
 	}
 
 	for i := len(used) - 1; i >= 0; i-- {
-		if !used[i] && !exprHasSetVar(p.Exprs[i]) {
+		if !used[i] && !exprHasSetVarOrSleep(p.Exprs[i]) {
 			p.schema.Columns = append(p.schema.Columns[:i], p.schema.Columns[i+1:]...)
 			p.Exprs = append(p.Exprs[:i], p.Exprs[i+1:]...)
 		}