updated the builder interface to return the new builder when doing a …

…MakeDistinct()

Signed-off-by: Andres Taylor <[email protected]>

go/vt/vtgate/planbuilder/builder.go

@@ -68,7 +68,7 @@ type builder interface {
 	PushSelect(pb *primitiveBuilder, expr *sqlparser.AliasedExpr, origin builder) (rc *resultColumn, colNumber int, err error)
 
 	// MakeDistinct makes the primitive handle the distinct clause.
-	MakeDistinct() error
+	MakeDistinct() (builder, error)
 	// PushGroupBy makes the primitive handle the GROUP BY clause.
 	PushGroupBy(sqlparser.GroupBy) error
 

go/vt/vtgate/planbuilder/concatenate.go

@@ -89,8 +89,8 @@ func (c *concatenate) PushSelect(pb *primitiveBuilder, expr *sqlparser.AliasedEx
 	return nil, 0, unreachable("Select")
 }
 
-func (c *concatenate) MakeDistinct() error {
-	return vterrors.New(vtrpc.Code_UNIMPLEMENTED, "only union-all is supported for this operator")
+func (c *concatenate) MakeDistinct() (builder, error) {
+	return nil, vterrors.New(vtrpc.Code_UNIMPLEMENTED, "only union-all is supported for this operator")
 }
 
 func (c *concatenate) PushGroupBy(by sqlparser.GroupBy) error {

go/vt/vtgate/planbuilder/distinct.go

@@ -46,8 +46,8 @@ func (d *distinct) PushSelect(pb *primitiveBuilder, expr *sqlparser.AliasedExpr,
 	return d.input.PushSelect(pb, expr, origin)
 }
 
-func (d *distinct) MakeDistinct() error {
-	return nil
+func (d *distinct) MakeDistinct() (builder, error) {
+	return d, nil
 }
 
 func (d *distinct) PushGroupBy(by sqlparser.GroupBy) error {

go/vt/vtgate/planbuilder/join.go

@@ -190,8 +190,8 @@ func (jb *join) PushSelect(pb *primitiveBuilder, expr *sqlparser.AliasedExpr, or
 }
 
 // MakeDistinct satisfies the builder interface.
-func (jb *join) MakeDistinct() error {
-	return errors.New("unsupported: distinct on cross-shard join")
+func (jb *join) MakeDistinct() (builder, error) {
+	return nil, errors.New("unsupported: distinct on cross-shard join")
 }
 
 // PushGroupBy satisfies the builder interface.

go/vt/vtgate/planbuilder/limit.go

@@ -66,8 +66,8 @@ func (l *limit) PushSelect(_ *primitiveBuilder, expr *sqlparser.AliasedExpr, ori
 }
 
 // MakeDistinct satisfies the builder interface.
-func (l *limit) MakeDistinct() error {
-	return errors.New("limit.MakeDistinct: unreachable")
+func (l *limit) MakeDistinct() (builder, error) {
+	return nil, errors.New("limit.MakeDistinct: unreachable")
 }
 
 // PushGroupBy satisfies the builder interface.

go/vt/vtgate/planbuilder/memory_sort.go

@@ -99,8 +99,8 @@ func (ms *memorySort) PushSelect(_ *primitiveBuilder, expr *sqlparser.AliasedExp
 }
 
 // MakeDistinct satisfies the builder interface.
-func (ms *memorySort) MakeDistinct() error {
-	return errors.New("memorySort.MakeDistinct: unreachable")
+func (ms *memorySort) MakeDistinct() (builder, error) {
+	return nil, errors.New("memorySort.MakeDistinct: unreachable")
 }
 
 // PushGroupBy satisfies the builder interface.

go/vt/vtgate/planbuilder/merge_sort.go

@@ -76,8 +76,13 @@ func (ms *mergeSort) PushSelect(pb *primitiveBuilder, expr *sqlparser.AliasedExp
 }
 
 // MakeDistinct satisfies the builder interface.
-func (ms *mergeSort) MakeDistinct() error {
-	return ms.input.MakeDistinct()
+func (ms *mergeSort) MakeDistinct() (builder, error) {
+	distinctSrc, err := ms.input.MakeDistinct()
+	if err != nil {
+		return nil, err
+	}
+	ms.input = distinctSrc
+	return ms, err
 }
 
 // PushGroupBy satisfies the builder interface.

go/vt/vtgate/planbuilder/ordered_aggregate.go

@@ -356,18 +356,23 @@ func (oa *orderedAggregate) needDistinctHandling(pb *primitiveBuilder, funcExpr
 	return true, innerAliased, nil
 }
 
-func (oa *orderedAggregate) MakeDistinct() error {
+func (oa *orderedAggregate) MakeDistinct() (builder, error) {
 	for i, rc := range oa.resultColumns {
 		// If the column origin is oa (and not the underlying route),
 		// it means that it's an aggregate function supplied by oa.
 		// So, the distinct 'operator' cannot be pushed down into the
 		// route.
 		if rc.column.Origin() == oa {
-			return errors.New("unsupported: distinct cannot be combined with aggregate functions")
+			return nil, errors.New("unsupported: distinct cannot be combined with aggregate functions")
 		}
 		oa.eaggr.Keys = append(oa.eaggr.Keys, i)
 	}
-	return oa.input.MakeDistinct()
+	distinctSrc, err := oa.input.MakeDistinct()
+	if err != nil {
+		return nil, err
+	}
+	oa.input=distinctSrc
+	return oa, err
 }
 
 // PushGroupBy satisfies the builder interface.

go/vt/vtgate/planbuilder/postprocess.go

@@ -27,9 +27,11 @@ import (
 // and ensures that there are no subqueries.
 func (pb *primitiveBuilder) pushGroupBy(sel *sqlparser.Select) error {
 	if sel.Distinct {
-		if err := pb.bldr.MakeDistinct(); err != nil {
+		newBuilder, err := pb.bldr.MakeDistinct()
+		if  err != nil {
 			return err
 		}
+		pb.bldr = newBuilder
 	}
 
 	if err := pb.st.ResolveSymbols(sel.GroupBy); err != nil {

go/vt/vtgate/planbuilder/pullout_subquery.go

@@ -102,8 +102,13 @@ func (ps *pulloutSubquery) PushSelect(pb *primitiveBuilder, expr *sqlparser.Alia
 }
 
 // MakeDistinct satisfies the builder interface.
-func (ps *pulloutSubquery) MakeDistinct() error {
-	return ps.underlying.MakeDistinct()
+func (ps *pulloutSubquery) MakeDistinct() (builder, error) {
+	distinctUnderlying, err := ps.underlying.MakeDistinct()
+	if err != nil {
+		return nil, err
+	}
+	ps.underlying = distinctUnderlying
+	return ps, err
 }
 
 // PushGroupBy satisfies the builder interface.

go/vt/vtgate/planbuilder/route.go

@@ -162,9 +162,9 @@ func (rb *route) PushAnonymous(expr sqlparser.SelectExpr) *resultColumn {
 }
 
 // MakeDistinct satisfies the builder interface.
-func (rb *route) MakeDistinct() error {
+func (rb *route) MakeDistinct() (builder, error) {
 	rb.Select.(*sqlparser.Select).Distinct = true
-	return nil
+	return rb, nil
 }
 
 // PushGroupBy satisfies the builder interface.

go/vt/vtgate/planbuilder/sql_calc_found_rows.go

@@ -80,8 +80,8 @@ func (s *sqlCalcFoundRows) PushSelect(*primitiveBuilder, *sqlparser.AliasedExpr,
 }
 
 //MakeDistinct implements the builder interface
-func (s *sqlCalcFoundRows) MakeDistinct() error {
-	return vterrors.Errorf(vtrpcpb.Code_INTERNAL, "unreachable: sqlCalcFoundRows.MakeDistinct")
+func (s *sqlCalcFoundRows) MakeDistinct() (builder, error) {
+	return nil, vterrors.Errorf(vtrpcpb.Code_INTERNAL, "unreachable: sqlCalcFoundRows.MakeDistinct")
 }
 
 //PushGroupBy implements the builder interface

go/vt/vtgate/planbuilder/subquery.go

@@ -113,8 +113,8 @@ func (sq *subquery) PushSelect(_ *primitiveBuilder, expr *sqlparser.AliasedExpr,
 }
 
 // MakeDistinct satisfies the builder interface.
-func (sq *subquery) MakeDistinct() error {
-	return errors.New("unsupported: distinct on cross-shard subquery")
+func (sq *subquery) MakeDistinct() (builder, error) {
+	return nil, errors.New("unsupported: distinct on cross-shard subquery")
 }
 
 // PushGroupBy satisfies the builder interface.

go/vt/vtgate/planbuilder/vindex_func.go

@@ -156,8 +156,8 @@ func (vf *vindexFunc) PushSelect(_ *primitiveBuilder, expr *sqlparser.AliasedExp
 }
 
 // MakeDistinct satisfies the builder interface.
-func (vf *vindexFunc) MakeDistinct() error {
-	return errors.New("unsupported: distinct on vindex function")
+func (vf *vindexFunc) MakeDistinct() (builder, error) {
+	return nil, errors.New("unsupported: distinct on vindex function")
 }
 
 // PushGroupBy satisfies the builder interface.