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431 lines
13 KiB
431 lines
13 KiB
// Copyright 2017 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 expression
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import (
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"fmt"
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"github.com/pingcap/parser/mysql"
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"github.com/pingcap/parser/terror"
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"github.com/pingcap/tidb/sessionctx"
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"github.com/pingcap/tidb/sessionctx/stmtctx"
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"github.com/pingcap/tidb/types"
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"github.com/pingcap/tidb/types/json"
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"github.com/pingcap/tidb/util/chunk"
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"github.com/pingcap/tidb/util/codec"
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)
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// NewOne stands for a number 1.
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func NewOne() *Constant {
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retT := types.NewFieldType(mysql.TypeTiny)
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retT.Flag |= mysql.UnsignedFlag // shrink range to avoid integral promotion
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return &Constant{
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Value: types.NewDatum(1),
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RetType: retT,
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}
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}
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// NewZero stands for a number 0.
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func NewZero() *Constant {
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retT := types.NewFieldType(mysql.TypeTiny)
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retT.Flag |= mysql.UnsignedFlag // shrink range to avoid integral promotion
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return &Constant{
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Value: types.NewDatum(0),
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RetType: retT,
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}
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}
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// NewNull stands for null constant.
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func NewNull() *Constant {
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return &Constant{
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Value: types.NewDatum(nil),
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RetType: types.NewFieldType(mysql.TypeTiny),
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}
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}
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// Constant stands for a constant value.
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type Constant struct {
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Value types.Datum
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RetType *types.FieldType
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// DeferredExpr holds deferred function in PlanCache cached plan.
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// it's only used to represent non-deterministic functions(see expression.DeferredFunctions)
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// in PlanCache cached plan, so let them can be evaluated until cached item be used.
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DeferredExpr Expression
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// ParamMarker holds param index inside sessionVars.PreparedParams.
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// It's only used to reference a user variable provided in the `EXECUTE` statement or `COM_EXECUTE` binary protocol.
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ParamMarker *ParamMarker
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hashcode []byte
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collationInfo
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}
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// ParamMarker indicates param provided by COM_STMT_EXECUTE.
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type ParamMarker struct {
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ctx sessionctx.Context
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order int
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}
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// GetUserVar returns the corresponding user variable presented in the `EXECUTE` statement or `COM_EXECUTE` command.
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func (d *ParamMarker) GetUserVar() types.Datum {
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sessionVars := d.ctx.GetSessionVars()
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return sessionVars.PreparedParams[d.order]
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}
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// String implements fmt.Stringer interface.
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func (c *Constant) String() string {
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if c.ParamMarker != nil {
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dt := c.ParamMarker.GetUserVar()
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c.Value.SetValue(dt.GetValue(), c.RetType)
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} else if c.DeferredExpr != nil {
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return c.DeferredExpr.String()
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}
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return fmt.Sprintf("%v", c.Value.GetValue())
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}
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// MarshalJSON implements json.Marshaler interface.
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func (c *Constant) MarshalJSON() ([]byte, error) {
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return []byte(fmt.Sprintf("\"%s\"", c)), nil
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}
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// Clone implements Expression interface.
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func (c *Constant) Clone() Expression {
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con := *c
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return &con
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}
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// GetType implements Expression interface.
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func (c *Constant) GetType() *types.FieldType {
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if c.ParamMarker != nil {
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// GetType() may be called in multi-threaded context, e.g, in building inner executors of IndexJoin,
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// so it should avoid data race. We achieve this by returning different FieldType pointer for each call.
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tp := types.NewFieldType(mysql.TypeUnspecified)
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dt := c.ParamMarker.GetUserVar()
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types.DefaultParamTypeForValue(dt.GetValue(), tp)
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return tp
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}
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return c.RetType
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}
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// VecEvalInt evaluates this expression in a vectorized manner.
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func (c *Constant) VecEvalInt(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error {
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if c.DeferredExpr == nil {
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return genVecFromConstExpr(ctx, c, types.ETInt, input, result)
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}
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return c.DeferredExpr.VecEvalInt(ctx, input, result)
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}
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// VecEvalReal evaluates this expression in a vectorized manner.
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func (c *Constant) VecEvalReal(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error {
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if c.DeferredExpr == nil {
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return genVecFromConstExpr(ctx, c, types.ETReal, input, result)
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}
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return c.DeferredExpr.VecEvalReal(ctx, input, result)
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}
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// VecEvalString evaluates this expression in a vectorized manner.
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func (c *Constant) VecEvalString(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error {
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if c.DeferredExpr == nil {
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return genVecFromConstExpr(ctx, c, types.ETString, input, result)
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}
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return c.DeferredExpr.VecEvalString(ctx, input, result)
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}
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// VecEvalDecimal evaluates this expression in a vectorized manner.
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func (c *Constant) VecEvalDecimal(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error {
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if c.DeferredExpr == nil {
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return genVecFromConstExpr(ctx, c, types.ETDecimal, input, result)
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}
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return c.DeferredExpr.VecEvalDecimal(ctx, input, result)
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}
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// VecEvalTime evaluates this expression in a vectorized manner.
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func (c *Constant) VecEvalTime(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error {
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if c.DeferredExpr == nil {
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return genVecFromConstExpr(ctx, c, types.ETTimestamp, input, result)
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}
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return c.DeferredExpr.VecEvalTime(ctx, input, result)
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}
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// VecEvalDuration evaluates this expression in a vectorized manner.
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func (c *Constant) VecEvalDuration(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error {
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if c.DeferredExpr == nil {
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return genVecFromConstExpr(ctx, c, types.ETDuration, input, result)
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}
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return c.DeferredExpr.VecEvalDuration(ctx, input, result)
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}
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// VecEvalJSON evaluates this expression in a vectorized manner.
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func (c *Constant) VecEvalJSON(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error {
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if c.DeferredExpr == nil {
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return genVecFromConstExpr(ctx, c, types.ETJson, input, result)
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}
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return c.DeferredExpr.VecEvalJSON(ctx, input, result)
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}
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func (c *Constant) getLazyDatum(row chunk.Row) (dt types.Datum, isLazy bool, err error) {
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if c.ParamMarker != nil {
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return c.ParamMarker.GetUserVar(), true, nil
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} else if c.DeferredExpr != nil {
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dt, err = c.DeferredExpr.Eval(row)
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return dt, true, err
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}
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return types.Datum{}, false, nil
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}
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// Eval implements Expression interface.
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func (c *Constant) Eval(row chunk.Row) (types.Datum, error) {
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if dt, lazy, err := c.getLazyDatum(row); lazy {
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if err != nil {
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return c.Value, err
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}
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if dt.IsNull() {
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c.Value.SetNull()
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return c.Value, nil
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}
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if c.DeferredExpr != nil {
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sf, sfOk := c.DeferredExpr.(*ScalarFunction)
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if sfOk {
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val, err := dt.ConvertTo(sf.GetCtx().GetSessionVars().StmtCtx, c.RetType)
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if err != nil {
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return dt, err
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}
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return val, nil
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}
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}
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return dt, nil
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}
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return c.Value, nil
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}
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// EvalInt returns int representation of Constant.
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func (c *Constant) EvalInt(ctx sessionctx.Context, row chunk.Row) (int64, bool, error) {
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dt, lazy, err := c.getLazyDatum(row)
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if err != nil {
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return 0, false, err
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}
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if !lazy {
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dt = c.Value
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}
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if c.GetType().Tp == mysql.TypeNull || dt.IsNull() {
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return 0, true, nil
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} else if dt.Kind() == types.KindBinaryLiteral {
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val, err := dt.GetBinaryLiteral().ToInt(ctx.GetSessionVars().StmtCtx)
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return int64(val), err != nil, err
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} else if c.GetType().Hybrid() || dt.Kind() == types.KindString {
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res, err := dt.ToInt64(ctx.GetSessionVars().StmtCtx)
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return res, false, err
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}
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return dt.GetInt64(), false, nil
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}
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// EvalReal returns real representation of Constant.
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func (c *Constant) EvalReal(ctx sessionctx.Context, row chunk.Row) (float64, bool, error) {
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dt, lazy, err := c.getLazyDatum(row)
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if err != nil {
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return 0, false, err
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}
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if !lazy {
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dt = c.Value
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}
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if c.GetType().Tp == mysql.TypeNull || dt.IsNull() {
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return 0, true, nil
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}
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if c.GetType().Hybrid() || dt.Kind() == types.KindBinaryLiteral || dt.Kind() == types.KindString {
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res, err := dt.ToFloat64(ctx.GetSessionVars().StmtCtx)
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return res, false, err
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}
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return dt.GetFloat64(), false, nil
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}
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// EvalString returns string representation of Constant.
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func (c *Constant) EvalString(ctx sessionctx.Context, row chunk.Row) (string, bool, error) {
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dt, lazy, err := c.getLazyDatum(row)
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if err != nil {
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return "", false, err
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}
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if !lazy {
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dt = c.Value
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}
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if c.GetType().Tp == mysql.TypeNull || dt.IsNull() {
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return "", true, nil
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}
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res, err := dt.ToString()
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return res, false, err
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}
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// EvalDecimal returns decimal representation of Constant.
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func (c *Constant) EvalDecimal(ctx sessionctx.Context, row chunk.Row) (*types.MyDecimal, bool, error) {
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dt, lazy, err := c.getLazyDatum(row)
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if err != nil {
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return nil, false, err
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}
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if !lazy {
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dt = c.Value
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}
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if c.GetType().Tp == mysql.TypeNull || dt.IsNull() {
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return nil, true, nil
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}
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res, err := dt.ToDecimal(ctx.GetSessionVars().StmtCtx)
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return res, false, err
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}
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// EvalTime returns DATE/DATETIME/TIMESTAMP representation of Constant.
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func (c *Constant) EvalTime(ctx sessionctx.Context, row chunk.Row) (val types.Time, isNull bool, err error) {
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dt, lazy, err := c.getLazyDatum(row)
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if err != nil {
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return types.ZeroTime, false, err
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}
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if !lazy {
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dt = c.Value
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}
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if c.GetType().Tp == mysql.TypeNull || dt.IsNull() {
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return types.ZeroTime, true, nil
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}
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return dt.GetMysqlTime(), false, nil
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}
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// EvalDuration returns Duration representation of Constant.
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func (c *Constant) EvalDuration(ctx sessionctx.Context, row chunk.Row) (val types.Duration, isNull bool, err error) {
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dt, lazy, err := c.getLazyDatum(row)
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if err != nil {
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return types.Duration{}, false, err
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}
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if !lazy {
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dt = c.Value
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}
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if c.GetType().Tp == mysql.TypeNull || dt.IsNull() {
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return types.Duration{}, true, nil
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}
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return dt.GetMysqlDuration(), false, nil
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}
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// EvalJSON returns JSON representation of Constant.
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func (c *Constant) EvalJSON(ctx sessionctx.Context, row chunk.Row) (json.BinaryJSON, bool, error) {
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dt, lazy, err := c.getLazyDatum(row)
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if err != nil {
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return json.BinaryJSON{}, false, err
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}
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if !lazy {
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dt = c.Value
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}
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if c.GetType().Tp == mysql.TypeNull || dt.IsNull() {
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return json.BinaryJSON{}, true, nil
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}
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return dt.GetMysqlJSON(), false, nil
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}
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// Equal implements Expression interface.
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func (c *Constant) Equal(ctx sessionctx.Context, b Expression) bool {
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y, ok := b.(*Constant)
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if !ok {
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return false
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}
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_, err1 := y.Eval(chunk.Row{})
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_, err2 := c.Eval(chunk.Row{})
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if err1 != nil || err2 != nil {
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return false
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}
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con, err := c.Value.CompareDatum(ctx.GetSessionVars().StmtCtx, &y.Value)
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if err != nil || con != 0 {
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return false
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}
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return true
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}
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// IsCorrelated implements Expression interface.
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func (c *Constant) IsCorrelated() bool {
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return false
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}
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// ConstItem implements Expression interface.
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func (c *Constant) ConstItem(sc *stmtctx.StatementContext) bool {
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return !sc.UseCache || (c.DeferredExpr == nil && c.ParamMarker == nil)
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}
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// Decorrelate implements Expression interface.
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func (c *Constant) Decorrelate(_ *Schema) Expression {
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return c
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}
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// HashCode implements Expression interface.
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func (c *Constant) HashCode(sc *stmtctx.StatementContext) []byte {
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if len(c.hashcode) > 0 {
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return c.hashcode
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}
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_, err := c.Eval(chunk.Row{})
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if err != nil {
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terror.Log(err)
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}
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c.hashcode = append(c.hashcode, constantFlag)
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c.hashcode, err = codec.EncodeValue(sc, c.hashcode, c.Value)
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if err != nil {
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terror.Log(err)
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}
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return c.hashcode
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}
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// ResolveIndices implements Expression interface.
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func (c *Constant) ResolveIndices(_ *Schema) (Expression, error) {
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return c, nil
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}
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func (c *Constant) resolveIndices(_ *Schema) error {
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return nil
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}
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// Vectorized returns if this expression supports vectorized evaluation.
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func (c *Constant) Vectorized() bool {
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if c.DeferredExpr != nil {
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return c.DeferredExpr.Vectorized()
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}
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return true
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}
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// SupportReverseEval checks whether the builtinFunc support reverse evaluation.
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func (c *Constant) SupportReverseEval() bool {
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if c.DeferredExpr != nil {
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return c.DeferredExpr.SupportReverseEval()
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}
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return true
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}
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// ReverseEval evaluates the only one column value with given function result.
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func (c *Constant) ReverseEval(sc *stmtctx.StatementContext, res types.Datum, rType types.RoundingType) (val types.Datum, err error) {
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return c.Value, nil
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}
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// Coercibility returns the coercibility value which is used to check collations.
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func (c *Constant) Coercibility() Coercibility {
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if c.HasCoercibility() {
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return c.collationInfo.Coercibility()
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}
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c.SetCoercibility(deriveCoercibilityForConstant(c))
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return c.collationInfo.Coercibility()
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}
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// ParamConstInExpression checks whether there's Param Marker in the given expression.
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func ParamConstInExpression(expr Expression) bool {
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switch x := expr.(type) {
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case *ScalarFunction:
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for _, arg := range x.GetArgs() {
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if ParamConstInExpression(arg) {
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return true
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}
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}
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case *Constant:
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return x.ParamMarker != nil
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}
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return false
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}
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