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compiler.go
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compiler.go
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// Copyright 2015 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 executor
import (
log "github.com/Sirupsen/logrus"
"github.com/juju/errors"
"github.com/pingcap/tidb/ast"
"github.com/pingcap/tidb/context"
"github.com/pingcap/tidb/infoschema"
"github.com/pingcap/tidb/plan"
)
// Compiler compiles an ast.StmtNode to a physical plan.
type Compiler struct {
}
// Compile compiles an ast.StmtNode to a physical plan.
func (c *Compiler) Compile(ctx context.Context, stmtNode ast.StmtNode) (*ExecStmt, error) {
infoSchema := GetInfoSchema(ctx)
if err := plan.Preprocess(stmtNode, infoSchema, ctx); err != nil {
return nil, errors.Trace(err)
}
// Validate should be after NameResolve.
if err := plan.Validate(stmtNode, false); err != nil {
return nil, errors.Trace(err)
}
finalPlan, err := plan.Optimize(ctx, stmtNode, infoSchema)
if err != nil {
return nil, errors.Trace(err)
}
// check whether the stmt is read only
readOnly := false
if e, ok := stmtNode.(*ast.ExecuteStmt); ok {
vars := ctx.GetSessionVars()
if id, ok := vars.PreparedStmtNameToID[e.Name]; ok {
v := vars.PreparedStmts[id]
if v == nil {
return nil, errors.Trace(ErrStmtNotFound)
}
prepared := v.(*Prepared)
readOnly = ast.IsReadOnly(prepared.Stmt)
}
} else {
readOnly = ast.IsReadOnly(stmtNode)
}
return &ExecStmt{
InfoSchema: infoSchema,
Plan: finalPlan,
Expensive: stmtCount(stmtNode, finalPlan, ctx.GetSessionVars().InRestrictedSQL),
Cacheable: plan.Cacheable(stmtNode),
Text: stmtNode.Text(),
ReadOnly: readOnly,
Ctx: ctx,
StmtNode: stmtNode,
}, nil
}
// GetInfoSchema gets TxnCtx InfoSchema if snapshot schema is not set,
// Otherwise, snapshot schema is returned.
func GetInfoSchema(ctx context.Context) infoschema.InfoSchema {
sessVar := ctx.GetSessionVars()
var is infoschema.InfoSchema
if snap := sessVar.SnapshotInfoschema; snap != nil {
is = snap.(infoschema.InfoSchema)
log.Infof("[%d] use snapshot schema %d", sessVar.ConnectionID, is.SchemaMetaVersion())
} else {
is = sessVar.TxnCtx.InfoSchema.(infoschema.InfoSchema)
}
return is
}