95 lines
2.5 KiB
Go
95 lines
2.5 KiB
Go
// Copyright 2014 The ql Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSES/QL-LICENSE file.
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// Copyright 2015 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package plans
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import (
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"github.com/juju/errors"
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"github.com/pingcap/tidb/context"
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"github.com/pingcap/tidb/expression"
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"github.com/pingcap/tidb/field"
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"github.com/pingcap/tidb/plan"
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"github.com/pingcap/tidb/util/format"
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"github.com/pingcap/tidb/util/types"
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)
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var (
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_ plan.Plan = (*FilterDefaultPlan)(nil)
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)
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// FilterDefaultPlan handles WHERE statement, filters rows by specific
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// expressions.
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type FilterDefaultPlan struct {
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plan.Plan
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Expr expression.Expression
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evalArgs map[interface{}]interface{}
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}
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// Explain implements plan.Plan Explain interface.
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func (r *FilterDefaultPlan) Explain(w format.Formatter) {
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r.Plan.Explain(w)
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w.Format("┌FilterDefaultPlan Filter on %v\n", r.Expr)
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w.Format("└Output field names %v\n", field.RFQNames(r.GetFields()))
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}
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// Next implements plan.Plan Next interface.
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func (r *FilterDefaultPlan) Next(ctx context.Context) (row *plan.Row, err error) {
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if r.evalArgs == nil {
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r.evalArgs = map[interface{}]interface{}{}
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}
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for {
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row, err = r.Plan.Next(ctx)
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if row == nil || err != nil {
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return nil, errors.Trace(err)
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}
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r.evalArgs[expression.ExprEvalIdentReferFunc] = func(name string, scope int, index int) (interface{}, error) {
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if scope == expression.IdentReferFromTable {
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return row.Data[index], nil
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}
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// try to find in outer query
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return getIdentValueFromOuterQuery(ctx, name)
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}
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var meet bool
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meet, err = r.meetCondition(ctx)
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if err != nil {
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return nil, errors.Trace(err)
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}
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if meet {
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return
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}
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}
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}
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func (r *FilterDefaultPlan) meetCondition(ctx context.Context) (bool, error) {
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val, err := r.Expr.Eval(ctx, r.evalArgs)
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if val == nil || err != nil {
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return false, errors.Trace(err)
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}
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x, err := types.ToBool(val)
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if err != nil {
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return false, errors.Trace(err)
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}
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return x == 1, nil
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}
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// Close implements plan.Plan Close interface.
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func (r *FilterDefaultPlan) Close() error {
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return r.Plan.Close()
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}
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