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planner: add HashCode method for LogicalPlan & use PlanHash for Group…
…Expr's fingerPrint (pingcap#14224)
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,99 @@ | ||
| // Copyright 2019 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 ( | ||
| "bytes" | ||
| "encoding/binary" | ||
| "sort" | ||
|
|
||
| "github.com/pingcap/tidb/util/plancodec" | ||
| ) | ||
|
|
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| func encodeIntAsUint32(result []byte, value int) []byte { | ||
| var buf [4]byte | ||
| binary.BigEndian.PutUint32(buf[:], uint32(value)) | ||
| return append(result, buf[:]...) | ||
| } | ||
|
|
||
| // HashCode implements LogicalPlan interface. | ||
| func (p *baseLogicalPlan) HashCode() []byte { | ||
| // We use PlanID for the default hash, so if two plans do not have | ||
| // the same id, the hash value will never be the same. | ||
| result := make([]byte, 0, 4) | ||
| result = encodeIntAsUint32(result, p.id) | ||
| return result | ||
| } | ||
|
|
||
| // HashCode implements LogicalPlan interface. | ||
| func (p *LogicalProjection) HashCode() []byte { | ||
| // PlanType + SelectOffset + ExprNum + [Exprs] | ||
| // Expressions are commonly `Column`s, whose hashcode has the length 9, so | ||
| // we pre-alloc 10 bytes for each expr's hashcode. | ||
| result := make([]byte, 0, 12+len(p.Exprs)*10) | ||
| result = encodeIntAsUint32(result, plancodec.TypeStringToPhysicalID(p.tp)) | ||
| result = encodeIntAsUint32(result, p.SelectBlockOffset()) | ||
| result = encodeIntAsUint32(result, len(p.Exprs)) | ||
| for _, expr := range p.Exprs { | ||
| exprHashCode := expr.HashCode(p.ctx.GetSessionVars().StmtCtx) | ||
| result = encodeIntAsUint32(result, len(exprHashCode)) | ||
| result = append(result, exprHashCode...) | ||
| } | ||
| return result | ||
| } | ||
|
|
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| // HashCode implements LogicalPlan interface. | ||
| func (p *LogicalTableDual) HashCode() []byte { | ||
| // PlanType + SelectOffset + RowCount | ||
| result := make([]byte, 0, 12) | ||
| result = encodeIntAsUint32(result, plancodec.TypeStringToPhysicalID(p.tp)) | ||
| result = encodeIntAsUint32(result, p.SelectBlockOffset()) | ||
| result = encodeIntAsUint32(result, p.RowCount) | ||
| return result | ||
| } | ||
|
|
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| // HashCode implements LogicalPlan interface. | ||
| func (p *LogicalSelection) HashCode() []byte { | ||
| // PlanType + SelectOffset + ConditionNum + [Conditions] | ||
| // Conditions are commonly `ScalarFunction`s, whose hashcode usually has a | ||
| // length larger than 20, so we pre-alloc 25 bytes for each expr's hashcode. | ||
| result := make([]byte, 0, 12+len(p.Conditions)*25) | ||
| result = encodeIntAsUint32(result, plancodec.TypeStringToPhysicalID(p.tp)) | ||
| result = encodeIntAsUint32(result, p.SelectBlockOffset()) | ||
| result = encodeIntAsUint32(result, len(p.Conditions)) | ||
|
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| condHashCodes := make([][]byte, len(p.Conditions)) | ||
| for i, expr := range p.Conditions { | ||
| condHashCodes[i] = expr.HashCode(p.ctx.GetSessionVars().StmtCtx) | ||
| } | ||
| // Sort the conditions, so `a > 1 and a < 100` can equal to `a < 100 and a > 1`. | ||
| sort.Slice(condHashCodes, func(i, j int) bool { return bytes.Compare(condHashCodes[i], condHashCodes[j]) < 0 }) | ||
|
|
||
| for _, condHashCode := range condHashCodes { | ||
| result = encodeIntAsUint32(result, len(condHashCode)) | ||
| result = append(result, condHashCode...) | ||
| } | ||
| return result | ||
| } | ||
|
|
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| // HashCode implements LogicalPlan interface. | ||
| func (p *LogicalLimit) HashCode() []byte { | ||
| // PlanType + SelectOffset + Offset + Count | ||
| result := make([]byte, 24) | ||
| binary.BigEndian.PutUint32(result, uint32(plancodec.TypeStringToPhysicalID(p.tp))) | ||
| binary.BigEndian.PutUint32(result[4:], uint32(p.SelectBlockOffset())) | ||
| binary.BigEndian.PutUint64(result[8:], p.Offset) | ||
| binary.BigEndian.PutUint64(result[16:], p.Count) | ||
| return result | ||
| } |
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