minio/pkg/s3select/sql/analysis.go

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/*
* MinIO Cloud Storage, (C) 2019 MinIO, Inc.
*
* 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 sql
import (
"errors"
"fmt"
)
// Query analysis - The query is analyzed to determine if it involves
// aggregation.
//
// Aggregation functions - An expression that involves aggregation of
// rows in some manner. Requires all input rows to be processed,
// before a result is returned.
//
// Row function - An expression that depends on a value in the
// row. They have an output for each input row.
//
// Some types of a queries are not valid. For example, an aggregation
// function combined with a row function is meaningless ("AVG(s.Age) +
// s.Salary"). Analysis determines if such a scenario exists so an
// error can be returned.
var (
// Fatal error for query processing.
errNestedAggregation = errors.New("Cannot nest aggregations")
errFunctionNotImplemented = errors.New("Function is not yet implemented")
errUnexpectedInvalidNode = errors.New("Unexpected node value")
errInvalidKeypath = errors.New("A provided keypath is invalid")
)
// qProp contains analysis info about an SQL term.
type qProp struct {
isAggregation, isRowFunc bool
err error
}
// `combine` combines a pair of `qProp`s, so that errors are
// propagated correctly, and checks that an aggregation is not being
// combined with a row-function term.
func (p *qProp) combine(q qProp) {
switch {
case p.err != nil:
// Do nothing
case q.err != nil:
p.err = q.err
default:
p.isAggregation = p.isAggregation || q.isAggregation
p.isRowFunc = p.isRowFunc || q.isRowFunc
if p.isAggregation && p.isRowFunc {
p.err = errNestedAggregation
}
}
}
func (e *SelectExpression) analyze(s *Select) (result qProp) {
if e.All {
return qProp{isRowFunc: true}
}
for _, ex := range e.Expressions {
result.combine(ex.analyze(s))
}
return
}
func (e *AliasedExpression) analyze(s *Select) qProp {
return e.Expression.analyze(s)
}
func (e *Expression) analyze(s *Select) (result qProp) {
for _, ac := range e.And {
result.combine(ac.analyze(s))
}
return
}
func (e *AndCondition) analyze(s *Select) (result qProp) {
for _, ac := range e.Condition {
result.combine(ac.analyze(s))
}
return
}
func (e *Condition) analyze(s *Select) (result qProp) {
if e.Operand != nil {
result = e.Operand.analyze(s)
} else {
result = e.Not.analyze(s)
}
return
}
func (e *ConditionOperand) analyze(s *Select) (result qProp) {
if e.ConditionRHS == nil {
result = e.Operand.analyze(s)
} else {
result.combine(e.Operand.analyze(s))
result.combine(e.ConditionRHS.analyze(s))
}
return
}
func (e *ConditionRHS) analyze(s *Select) (result qProp) {
switch {
case e.Compare != nil:
result = e.Compare.Operand.analyze(s)
case e.Between != nil:
result.combine(e.Between.Start.analyze(s))
result.combine(e.Between.End.analyze(s))
case e.In != nil:
for _, elt := range e.In.Expressions {
result.combine(elt.analyze(s))
}
case e.Like != nil:
result.combine(e.Like.Pattern.analyze(s))
if e.Like.EscapeChar != nil {
result.combine(e.Like.EscapeChar.analyze(s))
}
default:
result = qProp{err: errUnexpectedInvalidNode}
}
return
}
func (e *Operand) analyze(s *Select) (result qProp) {
result.combine(e.Left.analyze(s))
for _, r := range e.Right {
result.combine(r.Right.analyze(s))
}
return
}
func (e *MultOp) analyze(s *Select) (result qProp) {
result.combine(e.Left.analyze(s))
for _, r := range e.Right {
result.combine(r.Right.analyze(s))
}
return
}
func (e *UnaryTerm) analyze(s *Select) (result qProp) {
if e.Negated != nil {
result = e.Negated.Term.analyze(s)
} else {
result = e.Primary.analyze(s)
}
return
}
func (e *PrimaryTerm) analyze(s *Select) (result qProp) {
switch {
case e.Value != nil:
result = qProp{}
case e.JPathExpr != nil:
// Check if the path expression is valid
if len(e.JPathExpr.PathExpr) > 0 {
if e.JPathExpr.BaseKey.String() != s.From.As {
result = qProp{err: errInvalidKeypath}
return
}
}
result = qProp{isRowFunc: true}
case e.SubExpression != nil:
result = e.SubExpression.analyze(s)
case e.FuncCall != nil:
result = e.FuncCall.analyze(s)
default:
result = qProp{err: errUnexpectedInvalidNode}
}
return
}
func (e *FuncExpr) analyze(s *Select) (result qProp) {
funcName := e.getFunctionName()
switch funcName {
case sqlFnCast:
return e.Cast.Expr.analyze(s)
case sqlFnExtract:
return e.Extract.From.analyze(s)
case sqlFnDateAdd:
result.combine(e.DateAdd.Quantity.analyze(s))
result.combine(e.DateAdd.Timestamp.analyze(s))
return result
case sqlFnDateDiff:
result.combine(e.DateDiff.Timestamp1.analyze(s))
result.combine(e.DateDiff.Timestamp2.analyze(s))
return result
// Handle aggregation function calls
case aggFnAvg, aggFnMax, aggFnMin, aggFnSum, aggFnCount:
// Initialize accumulator
e.aggregate = newAggVal(funcName)
var exprA qProp
if funcName == aggFnCount {
if e.Count.StarArg {
return qProp{isAggregation: true}
}
exprA = e.Count.ExprArg.analyze(s)
} else {
if len(e.SFunc.ArgsList) != 1 {
return qProp{err: fmt.Errorf("%s takes exactly one argument", funcName)}
}
exprA = e.SFunc.ArgsList[0].analyze(s)
}
if exprA.err != nil {
return exprA
}
if exprA.isAggregation {
return qProp{err: errNestedAggregation}
}
return qProp{isAggregation: true}
case sqlFnCoalesce:
if len(e.SFunc.ArgsList) == 0 {
return qProp{err: fmt.Errorf("%s needs at least one argument", string(funcName))}
}
for _, arg := range e.SFunc.ArgsList {
result.combine(arg.analyze(s))
}
return result
case sqlFnNullIf:
if len(e.SFunc.ArgsList) != 2 {
return qProp{err: fmt.Errorf("%s needs exactly 2 arguments", string(funcName))}
}
for _, arg := range e.SFunc.ArgsList {
result.combine(arg.analyze(s))
}
return result
case sqlFnCharLength, sqlFnCharacterLength:
if len(e.SFunc.ArgsList) != 1 {
return qProp{err: fmt.Errorf("%s needs exactly 2 arguments", string(funcName))}
}
for _, arg := range e.SFunc.ArgsList {
result.combine(arg.analyze(s))
}
return result
case sqlFnLower, sqlFnUpper:
if len(e.SFunc.ArgsList) != 1 {
return qProp{err: fmt.Errorf("%s needs exactly 2 arguments", string(funcName))}
}
for _, arg := range e.SFunc.ArgsList {
result.combine(arg.analyze(s))
}
return result
case sqlFnSubstring:
errVal := fmt.Errorf("Invalid argument(s) to %s", string(funcName))
result.combine(e.Substring.Expr.analyze(s))
switch {
case e.Substring.From != nil:
result.combine(e.Substring.From.analyze(s))
if e.Substring.For != nil {
result.combine(e.Substring.Expr.analyze(s))
}
case e.Substring.Arg2 != nil:
result.combine(e.Substring.Arg2.analyze(s))
if e.Substring.Arg3 != nil {
result.combine(e.Substring.Arg3.analyze(s))
}
default:
result.err = errVal
}
return result
case sqlFnUTCNow:
if len(e.SFunc.ArgsList) != 0 {
result.err = fmt.Errorf("%s() takes no arguments", string(funcName))
}
return result
}
// TODO: implement other functions
return qProp{err: errFunctionNotImplemented}
}