pullout_subquery.go

/*
Copyright 2018 The Vitess Authors.

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,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package planbuilder

import (
	"vitess.io/vitess/go/vt/sqlparser"
	"vitess.io/vitess/go/vt/vtgate/engine"
)

var _ builder = (*pulloutSubquery)(nil)

// pulloutSubquery is the builder for engine.PulloutSubquery.
// This gets built if a subquery is not correlated and can
// therefore can be pulled out and executed upfront.
type pulloutSubquery struct {
	order      int
	subquery   builder
	underlying builder
	eSubquery  *engine.PulloutSubquery
}

// newPulloutSubquery builds a new pulloutSubquery.
func newPulloutSubquery(opcode engine.PulloutOpcode, sqName, hasValues string, subquery builder) *pulloutSubquery {
	return &pulloutSubquery{
		subquery: subquery,
		eSubquery: &engine.PulloutSubquery{
			Opcode:         opcode,
			SubqueryResult: sqName,
			HasValues:      hasValues,
		},
	}
}

// setUnderlying sets the underlying primitive.
func (ps *pulloutSubquery) setUnderlying(underlying builder) {
	ps.underlying = underlying
	ps.underlying.Reorder(ps.subquery.Order())
	ps.order = ps.underlying.Order() + 1
}

// Order satisfies the builder interface.
func (ps *pulloutSubquery) Order() int {
	return ps.order
}

// Reorder satisfies the builder interface.
func (ps *pulloutSubquery) Reorder(order int) {
	ps.subquery.Reorder(order)
	ps.underlying.Reorder(ps.subquery.Order())
	ps.order = ps.underlying.Order() + 1
}

// Primitive satisfies the builder interface.
func (ps *pulloutSubquery) Primitive() engine.Primitive {
	ps.eSubquery.Subquery = ps.subquery.Primitive()
	ps.eSubquery.Underlying = ps.underlying.Primitive()
	return ps.eSubquery
}

// First satisfies the builder interface.
func (ps *pulloutSubquery) First() builder {
	return ps.underlying.First()
}

// ResultColumns satisfies the builder interface.
func (ps *pulloutSubquery) ResultColumns() []*resultColumn {
	return ps.underlying.ResultColumns()
}

// PushFilter satisfies the builder interface.
func (ps *pulloutSubquery) PushFilter(pb *primitiveBuilder, filter sqlparser.Expr, whereType string, origin builder) error {
	return ps.underlying.PushFilter(pb, filter, whereType, origin)
}

// PushSelect satisfies the builder interface.
func (ps *pulloutSubquery) PushSelect(expr *sqlparser.AliasedExpr, origin builder) (rc *resultColumn, colnum int, err error) {
	return ps.underlying.PushSelect(expr, origin)
}

// PushOrderByNull satisfies the builder interface.
func (ps *pulloutSubquery) PushOrderByNull() {
	ps.underlying.PushOrderByNull()
}

// PushOrderByRand satisfies the builder interface.
func (ps *pulloutSubquery) PushOrderByRand() {
	ps.underlying.PushOrderByRand()
}

// SetUpperLimit satisfies the builder interface.
// This is a no-op because we actually call SetLimit for this primitive.
// In the future, we may have to honor this call for subqueries.
func (ps *pulloutSubquery) SetUpperLimit(count *sqlparser.SQLVal) {
	ps.underlying.SetUpperLimit(count)
}

// PushMisc satisfies the builder interface.
func (ps *pulloutSubquery) PushMisc(sel *sqlparser.Select) {
	ps.subquery.PushMisc(sel)
	ps.underlying.PushMisc(sel)
}

// Wireup satisfies the builder interface.
func (ps *pulloutSubquery) Wireup(bldr builder, jt *jointab) error {
	if err := ps.underlying.Wireup(bldr, jt); err != nil {
		return err
	}
	return ps.subquery.Wireup(bldr, jt)
}

// SupplyVar satisfies the builder interface.
func (ps *pulloutSubquery) SupplyVar(from, to int, col *sqlparser.ColName, varname string) {
	if from <= ps.subquery.Order() {
		ps.subquery.SupplyVar(from, to, col, varname)
		return
	}
	ps.underlying.SupplyVar(from, to, col, varname)
}

// SupplyCol satisfies the builder interface.
func (ps *pulloutSubquery) SupplyCol(col *sqlparser.ColName) (rc *resultColumn, colnum int) {
	panic("BUG: unreachable")
}