98 lines
2.8 KiB
Go
98 lines
2.8 KiB
Go
// Copyright 2017 PingCAP, 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,
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package core
|
|
|
|
import (
|
|
"github.com/pingcap/parser/ast"
|
|
"github.com/pingcap/tidb/expression"
|
|
"github.com/pingcap/tidb/types/parser_driver"
|
|
)
|
|
|
|
// Cacheable checks whether the input ast is cacheable.
|
|
func Cacheable(node ast.Node) bool {
|
|
_, isSelect := node.(*ast.SelectStmt)
|
|
_, isUpdate := node.(*ast.UpdateStmt)
|
|
_, isInsert := node.(*ast.InsertStmt)
|
|
_, isDelete := node.(*ast.DeleteStmt)
|
|
if !(isSelect || isUpdate || isInsert || isDelete) {
|
|
return false
|
|
}
|
|
checker := cacheableChecker{
|
|
cacheable: true,
|
|
}
|
|
node.Accept(&checker)
|
|
return checker.cacheable
|
|
}
|
|
|
|
// cacheableChecker checks whether a query's plan can be cached, querys that:
|
|
// 1. have ExistsSubqueryExpr, or
|
|
// 2. have VariableExpr
|
|
// will not be cached currently.
|
|
// NOTE: we can add more rules in the future.
|
|
type cacheableChecker struct {
|
|
cacheable bool
|
|
}
|
|
|
|
// Enter implements Visitor interface.
|
|
func (checker *cacheableChecker) Enter(in ast.Node) (out ast.Node, skipChildren bool) {
|
|
switch node := in.(type) {
|
|
case *ast.VariableExpr, *ast.ExistsSubqueryExpr, *ast.SubqueryExpr:
|
|
checker.cacheable = false
|
|
return in, true
|
|
case *ast.FuncCallExpr:
|
|
if _, found := expression.UnCacheableFunctions[node.FnName.L]; found {
|
|
checker.cacheable = false
|
|
return in, true
|
|
}
|
|
case *ast.OrderByClause:
|
|
for _, item := range node.Items {
|
|
if _, isParamMarker := item.Expr.(*driver.ParamMarkerExpr); isParamMarker {
|
|
checker.cacheable = false
|
|
return in, true
|
|
}
|
|
}
|
|
case *ast.GroupByClause:
|
|
for _, item := range node.Items {
|
|
if _, isParamMarker := item.Expr.(*driver.ParamMarkerExpr); isParamMarker {
|
|
checker.cacheable = false
|
|
return in, true
|
|
}
|
|
}
|
|
case *ast.Limit:
|
|
if node.Count != nil {
|
|
if _, isParamMarker := node.Count.(*driver.ParamMarkerExpr); isParamMarker {
|
|
checker.cacheable = false
|
|
return in, true
|
|
}
|
|
}
|
|
if node.Offset != nil {
|
|
if _, isParamMarker := node.Offset.(*driver.ParamMarkerExpr); isParamMarker {
|
|
checker.cacheable = false
|
|
return in, true
|
|
}
|
|
}
|
|
case *ast.FrameBound:
|
|
if _, ok := node.Expr.(*driver.ParamMarkerExpr); ok {
|
|
checker.cacheable = false
|
|
return in, true
|
|
}
|
|
}
|
|
return in, false
|
|
}
|
|
|
|
// Leave implements Visitor interface.
|
|
func (checker *cacheableChecker) Leave(in ast.Node) (out ast.Node, ok bool) {
|
|
return in, checker.cacheable
|
|
}
|