opt: introduce optimizer expression trees and build them from TypedExprs

This change brings in a subset of
https://github.com/petermattis/opttoy/tree/master/v3

This change introduces:

 - the expr tree: cascades-style optimizers operate on expression
   trees which can represent both scalar and relational expressions;
   this is a departure from the way we represent expressions and
   statements (sem/tree) so we need a new tree structure.

 - scalar operators: initially, we focus only on scalar expressions.

 - building an expr tree from a sem/tree.TypedExpr.

 - opt version of logic tests

See the RFC in cockroachdb#19135 for more context on the optimizer.

This is the first step of an initial project related to the optimizer:
generating index constraints from scalar expressions. This will be a
rewrite of the current index constraint generation code (which has
many problems, see cockroachdb#6346).  Roughly, the existing
`makeIndexConstraints` will call into the optimizer with a `TypedExpr`
and the optimizer will return index constraints.

Release note: None

pkg/sql/opt/build.go

@@ -0,0 +1,161 @@
+// Copyright 2017 The Cockroach 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 opt
+
+import (
+	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
+)
+
+// Map from tree.ComparisonOperator to operator.
+var comparisonOpMap = [...]operator{
+	tree.EQ:                eqOp,
+	tree.LT:                ltOp,
+	tree.GT:                gtOp,
+	tree.LE:                leOp,
+	tree.GE:                geOp,
+	tree.NE:                neOp,
+	tree.In:                inOp,
+	tree.NotIn:             notInOp,
+	tree.Like:              likeOp,
+	tree.NotLike:           notLikeOp,
+	tree.ILike:             iLikeOp,
+	tree.NotILike:          notILikeOp,
+	tree.SimilarTo:         similarToOp,
+	tree.NotSimilarTo:      notSimilarToOp,
+	tree.RegMatch:          regMatchOp,
+	tree.NotRegMatch:       notRegMatchOp,
+	tree.RegIMatch:         regIMatchOp,
+	tree.NotRegIMatch:      notRegIMatchOp,
+	tree.IsDistinctFrom:    isDistinctFromOp,
+	tree.IsNotDistinctFrom: isNotDistinctFromOp,
+	tree.Is:                isOp,
+	tree.IsNot:             isNotOp,
+	tree.Any:               anyOp,
+	tree.Some:              someOp,
+	tree.All:               allOp,
+}
+
+// Map from tree.BinaryOperator to operator.
+var binaryOpMap = [...]operator{
+	tree.Bitand:   bitandOp,
+	tree.Bitor:    bitorOp,
+	tree.Bitxor:   bitxorOp,
+	tree.Plus:     plusOp,
+	tree.Minus:    minusOp,
+	tree.Mult:     multOp,
+	tree.Div:      divOp,
+	tree.FloorDiv: floorDivOp,
+	tree.Mod:      modOp,
+	tree.Pow:      powOp,
+	tree.Concat:   concatOp,
+	tree.LShift:   lShiftOp,
+	tree.RShift:   rShiftOp,
+}
+
+// Map from tree.UnaryOperator to operator.
+var unaryOpMap = [...]operator{
+	tree.UnaryPlus:       unaryPlusOp,
+	tree.UnaryMinus:      unaryMinusOp,
+	tree.UnaryComplement: unaryComplementOp,
+}
+
+// We allocate *scalarProps and *expr in chunks of these sizes.
+const exprAllocChunk = 16
+const scalarPropsAllocChunk = 16
+
+type buildContext struct {
+	preallocScalarProps []scalarProps
+	preallocExprs       []expr
+}
+
+func (bc *buildContext) newScalarProps() *scalarProps {
+	if len(bc.preallocScalarProps) == 0 {
+		bc.preallocScalarProps = make([]scalarProps, scalarPropsAllocChunk)
+	}
+	p := &bc.preallocScalarProps[0]
+	bc.preallocScalarProps = bc.preallocScalarProps[1:]
+	return p
+}
+
+// newExpr returns a new *expr with a new, blank scalarProps.
+func (bc *buildContext) newExpr() *expr {
+	if len(bc.preallocExprs) == 0 {
+		bc.preallocExprs = make([]expr, exprAllocChunk)
+	}
+	e := &bc.preallocExprs[0]
+	bc.preallocExprs = bc.preallocExprs[1:]
+	e.scalarProps = bc.newScalarProps()
+	return e
+}
+
+// buildScalar converts a tree.TypedExpr to an expr tree.
+func buildScalar(buildCtx *buildContext, pexpr tree.TypedExpr) *expr {
+	switch t := pexpr.(type) {
+	case *tree.ParenExpr:
+		return buildScalar(buildCtx, t.TypedInnerExpr())
+	}
+
+	e := buildCtx.newExpr()
+	e.scalarProps.typ = pexpr.ResolvedType()
+
+	switch t := pexpr.(type) {
+	case *tree.AndExpr:
+		initBinaryExpr(
+			e, andOp,
+			buildScalar(buildCtx, t.TypedLeft()),
+			buildScalar(buildCtx, t.TypedRight()),
+		)
+	case *tree.OrExpr:
+		initBinaryExpr(
+			e, orOp,
+			buildScalar(buildCtx, t.TypedLeft()),
+			buildScalar(buildCtx, t.TypedRight()),
+		)
+	case *tree.NotExpr:
+		initUnaryExpr(e, notOp, buildScalar(buildCtx, t.TypedInnerExpr()))
+
+	case *tree.BinaryExpr:
+		initBinaryExpr(
+			e, binaryOpMap[t.Operator],
+			buildScalar(buildCtx, t.TypedLeft()),
+			buildScalar(buildCtx, t.TypedRight()),
+		)
+	case *tree.ComparisonExpr:
+		initBinaryExpr(
+			e, comparisonOpMap[t.Operator],
+			buildScalar(buildCtx, t.TypedLeft()),
+			buildScalar(buildCtx, t.TypedRight()),
+		)
+	case *tree.UnaryExpr:
+		initUnaryExpr(e, unaryOpMap[t.Operator], buildScalar(buildCtx, t.TypedInnerExpr()))
+
+	case *tree.FuncExpr:
+		children := make([]*expr, len(t.Exprs))
+		for i, pexpr := range t.Exprs {
+			children[i] = buildScalar(buildCtx, pexpr.(tree.TypedExpr))
+		}
+		initFunctionCallExpr(e, t.ResolvedFunc(), children)
+
+	case *tree.IndexedVar:
+		initVariableExpr(e, t.Idx)
+
+	case tree.Datum:
+		initConstExpr(e, t)
+
+	default:
+		panicf("node %T not supported", t)
+	}
+	return e
+}

pkg/sql/opt/expr.go

@@ -0,0 +1,70 @@
+// Copyright 2017 The Cockroach 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 opt
+
+import "github.com/cockroachdb/cockroach/pkg/util/treeprinter"
+
+// expr implements the node of a unified expressions tree for both relational
+// and scalar expressions in a query.
+//
+// Expressions have optional inputs. Expressions also maintain properties. For
+// scalar expressions, the properties are stored in scalarProps.
+//
+// Currently, it only supports scalar expressions and operators. More
+// information pertaining to relational operators will be added when they are
+// supported.
+//
+// TODO(radu): support relational operators and extend this description.
+type expr struct {
+	op operator
+	// Child expressions. The interpretation of the children is operator
+	// dependent.
+	children []*expr
+	// Scalar properties (properties that pertain only to scalar operators).
+	scalarProps *scalarProps
+	// Operator-dependent data used by this expression. For example, constOp
+	// stores a pointer to the constant value.
+	private interface{}
+}
+
+func (e *expr) opClass() operatorClass {
+	return operatorTab[e.op].class
+}
+
+func (e *expr) inputs() []*expr {
+	return e.children
+}
+
+func formatExprs(tp treeprinter.Node, title string, exprs []*expr) {
+	if len(exprs) > 0 {
+		n := tp.Child(title)
+		for _, e := range exprs {
+			if e != nil {
+				e.format(n)
+			}
+		}
+	}
+}
+
+// format is part of the operatorInfo interface.
+func (e *expr) format(tp treeprinter.Node) {
+	e.opClass().format(e, tp)
+}
+
+func (e *expr) String() string {
+	tp := treeprinter.New()
+	e.format(tp)
+	return tp.String()
+}

pkg/sql/opt/misc.go

@@ -0,0 +1,21 @@
+// Copyright 2017 The Cockroach 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 opt
+
+import "fmt"
+
+func panicf(format string, args ...interface{}) {
+	panic(fmt.Sprintf(format, args...))
+}

pkg/sql/opt/operator.go

@@ -0,0 +1,131 @@
+// Copyright 2017 The Cockroach 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 opt
+
+import (
+	"fmt"
+
+	"github.com/cockroachdb/cockroach/pkg/util/treeprinter"
+)
+
+type operator uint8
+
+const (
+	unknownOp operator = iota
+
+	// TODO(radu): no relational operators yet.
+
+	// -- Scalar operators --
+
+	// variableOp is a leaf expression that represents a non-constant value, like a column
+	// in a table.
+	variableOp
+
+	// constOp is a leaf expression that has a constant value.
+	constOp
+
+	// listOp is an unordered list of expressions. Currently unused.
+	listOp
+
+	// orderedListOp is an ordered list of expressions. Currently unused.
+	orderedListOp
+
+	andOp
+	orOp
+	notOp
+
+	eqOp
+	ltOp
+	gtOp
+	leOp
+	geOp
+	neOp
+	inOp
+	notInOp
+	likeOp
+	notLikeOp
+	iLikeOp
+	notILikeOp
+	similarToOp
+	notSimilarToOp
+	regMatchOp
+	notRegMatchOp
+	regIMatchOp
+	notRegIMatchOp
+	isDistinctFromOp
+	isNotDistinctFromOp
+	isOp
+	isNotOp
+	anyOp
+	someOp
+	allOp
+
+	bitandOp
+	bitorOp
+	bitxorOp
+	plusOp
+	minusOp
+	multOp
+	divOp
+	floorDivOp
+	modOp
+	powOp
+	concatOp
+	lShiftOp
+	rShiftOp
+
+	unaryPlusOp
+	unaryMinusOp
+	unaryComplementOp
+
+	functionCallOp
+
+	numOperators
+)
+
+// operatorInfo stores static information about an operator.
+type operatorInfo struct {
+	// name of the operator, used when printing expressions.
+	name string
+	// class of the operator (see operatorClass).
+	class operatorClass
+}
+
+// operatorTab stores static information about all operators.
+var operatorTab = [numOperators]operatorInfo{
+	unknownOp: {name: "unknown"},
+}
+
+func (op operator) String() string {
+	if op >= numOperators {
+		return fmt.Sprintf("operator(%d)", op)
+	}
+	return operatorTab[op].name
+}
+
+// registerOperator initializes the operator's entry in operatorTab.
+// There must be a call to registerOperator in an init() function for every
+// operator.
+func registerOperator(op operator, name string, class operatorClass) {
+	operatorTab[op].name = name
+	operatorTab[op].class = class
+}
+
+// operatorClass implements functionality that is common for a subset of
+// operators.
+type operatorClass interface {
+	// format outputs information about the expr tree to a treePrinter.
+	format(e *expr, tp treeprinter.Node)
+}