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planner: Move the Selectivity function from the stats package into ca…
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,207 @@ | ||
| // Copyright 2023 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, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| package cardinality | ||
|
|
||
| import ( | ||
| "bytes" | ||
|
|
||
| "github.com/pingcap/tidb/kv" | ||
| "github.com/pingcap/tidb/parser/mysql" | ||
| "github.com/pingcap/tidb/sessionctx" | ||
| "github.com/pingcap/tidb/sessionctx/stmtctx" | ||
| "github.com/pingcap/tidb/statistics" | ||
| "github.com/pingcap/tidb/types" | ||
| "github.com/pingcap/tidb/util/chunk" | ||
| "github.com/pingcap/tidb/util/logutil" | ||
| "github.com/pingcap/tidb/util/ranger" | ||
| "go.uber.org/zap" | ||
| ) | ||
|
|
||
| // NewHistCollBySelectivity creates new HistColl by the given statsNodes. | ||
| // TODO: remove this function after removing docs.pingcap.com/tidb/stable/system-variables#tidb_optimizer_selectivity_level. | ||
| func NewHistCollBySelectivity(sctx sessionctx.Context, coll *statistics.HistColl, statsNodes []*StatsNode) *statistics.HistColl { | ||
| newColl := &statistics.HistColl{ | ||
| Columns: make(map[int64]*statistics.Column), | ||
| Indices: make(map[int64]*statistics.Index), | ||
| Idx2ColumnIDs: coll.Idx2ColumnIDs, | ||
| ColID2IdxIDs: coll.ColID2IdxIDs, | ||
| RealtimeCount: coll.RealtimeCount, | ||
| } | ||
| for _, node := range statsNodes { | ||
| if node.Tp == IndexType { | ||
| idxHist, ok := coll.Indices[node.ID] | ||
| if !ok { | ||
| continue | ||
| } | ||
| newIdxHist, err := newIndexBySelectivity(sctx.GetSessionVars().StmtCtx, idxHist, node) | ||
| if err != nil { | ||
| logutil.BgLogger().Warn("something wrong happened when calculating row count, "+ | ||
| "failed to build histogram for index %v of table %v", | ||
| zap.String("category", "Histogram-in-plan"), zap.String("index", idxHist.Info.Name.O), | ||
| zap.String("table", idxHist.Info.Table.O), zap.Error(err)) | ||
| continue | ||
| } | ||
| newColl.Indices[node.ID] = newIdxHist | ||
| continue | ||
| } | ||
| oldCol, ok := coll.Columns[node.ID] | ||
| if !ok { | ||
| continue | ||
| } | ||
| newCol := &statistics.Column{ | ||
| PhysicalID: oldCol.PhysicalID, | ||
| Info: oldCol.Info, | ||
| IsHandle: oldCol.IsHandle, | ||
| CMSketch: oldCol.CMSketch, | ||
| } | ||
| newCol.Histogram = *statistics.NewHistogram(oldCol.ID, int64(float64(oldCol.Histogram.NDV)*node.Selectivity), 0, 0, oldCol.Tp, chunk.InitialCapacity, 0) | ||
| var err error | ||
| splitRanges, ok := oldCol.Histogram.SplitRange(sctx.GetSessionVars().StmtCtx, node.Ranges, false) | ||
| if !ok { | ||
| logutil.BgLogger().Warn("the type of histogram and ranges mismatch", zap.String("category", "Histogram-in-plan")) | ||
| continue | ||
| } | ||
| // Deal with some corner case. | ||
| if len(splitRanges) > 0 { | ||
| // Deal with NULL values. | ||
| if splitRanges[0].LowVal[0].IsNull() { | ||
| newCol.NullCount = oldCol.NullCount | ||
| if splitRanges[0].HighVal[0].IsNull() { | ||
| splitRanges = splitRanges[1:] | ||
| } else { | ||
| splitRanges[0].LowVal[0].SetMinNotNull() | ||
| } | ||
| } | ||
| } | ||
| if oldCol.IsHandle { | ||
| err = newHistogramBySelectivity(sctx, node.ID, &oldCol.Histogram, &newCol.Histogram, splitRanges, coll.GetRowCountByIntColumnRanges) | ||
| } else { | ||
| err = newHistogramBySelectivity(sctx, node.ID, &oldCol.Histogram, &newCol.Histogram, splitRanges, coll.GetRowCountByColumnRanges) | ||
| } | ||
| if err != nil { | ||
| logutil.BgLogger().Warn("something wrong happened when calculating row count", zap.String("category", "Histogram-in-plan"), | ||
| zap.Error(err)) | ||
| continue | ||
| } | ||
| newCol.StatsLoadedStatus = oldCol.StatsLoadedStatus | ||
| newColl.Columns[node.ID] = newCol | ||
| } | ||
| for id, idx := range coll.Indices { | ||
| _, ok := newColl.Indices[id] | ||
| if !ok { | ||
| newColl.Indices[id] = idx | ||
| } | ||
| } | ||
| for id, col := range coll.Columns { | ||
| _, ok := newColl.Columns[id] | ||
| if !ok { | ||
| newColl.Columns[id] = col | ||
| } | ||
| } | ||
| return newColl | ||
| } | ||
|
|
||
| type countByRangeFunc = func(sessionctx.Context, int64, []*ranger.Range) (float64, error) | ||
|
|
||
| // newHistogramBySelectivity fulfills the content of new histogram by the given selectivity result. | ||
| // TODO: remove this function after removing docs.pingcap.com/tidb/stable/system-variables#tidb_optimizer_selectivity_level. | ||
| func newHistogramBySelectivity(sctx sessionctx.Context, histID int64, oldHist, newHist *statistics.Histogram, ranges []*ranger.Range, cntByRangeFunc countByRangeFunc) error { | ||
| cntPerVal := int64(oldHist.AvgCountPerNotNullValue(int64(oldHist.TotalRowCount()))) | ||
| var totCnt int64 | ||
| for boundIdx, ranIdx, highRangeIdx := 0, 0, 0; boundIdx < oldHist.Bounds.NumRows() && ranIdx < len(ranges); boundIdx, ranIdx = boundIdx+2, highRangeIdx { | ||
| for highRangeIdx < len(ranges) && chunk.Compare(oldHist.Bounds.GetRow(boundIdx+1), 0, &ranges[highRangeIdx].HighVal[0]) >= 0 { | ||
| highRangeIdx++ | ||
| } | ||
| if boundIdx+2 >= oldHist.Bounds.NumRows() && highRangeIdx < len(ranges) && ranges[highRangeIdx].HighVal[0].Kind() == types.KindMaxValue { | ||
| highRangeIdx++ | ||
| } | ||
| if ranIdx == highRangeIdx { | ||
| continue | ||
| } | ||
| cnt, err := cntByRangeFunc(sctx, histID, ranges[ranIdx:highRangeIdx]) | ||
| // This should not happen. | ||
| if err != nil { | ||
| return err | ||
| } | ||
| if cnt == 0 { | ||
| continue | ||
| } | ||
| if int64(cnt) > oldHist.BucketCount(boundIdx/2) { | ||
| cnt = float64(oldHist.BucketCount(boundIdx / 2)) | ||
| } | ||
| newHist.Bounds.AppendRow(oldHist.Bounds.GetRow(boundIdx)) | ||
| newHist.Bounds.AppendRow(oldHist.Bounds.GetRow(boundIdx + 1)) | ||
| totCnt += int64(cnt) | ||
| bkt := statistics.Bucket{Count: totCnt} | ||
| if chunk.Compare(oldHist.Bounds.GetRow(boundIdx+1), 0, &ranges[highRangeIdx-1].HighVal[0]) == 0 && !ranges[highRangeIdx-1].HighExclude { | ||
| bkt.Repeat = cntPerVal | ||
| } | ||
| newHist.Buckets = append(newHist.Buckets, bkt) | ||
| switch newHist.Tp.EvalType() { | ||
| case types.ETString, types.ETDecimal, types.ETDatetime, types.ETTimestamp: | ||
| newHist.Scalars = append(newHist.Scalars, oldHist.Scalars[boundIdx/2]) | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| // TODO: remove this function after removing docs.pingcap.com/tidb/stable/system-variables#tidb_optimizer_selectivity_level. | ||
| func newIndexBySelectivity(sc *stmtctx.StatementContext, idx *statistics.Index, statsNode *StatsNode) (*statistics.Index, error) { | ||
| var ( | ||
| ranLowEncode, ranHighEncode []byte | ||
| err error | ||
| ) | ||
| newIndexHist := &statistics.Index{Info: idx.Info, StatsVer: idx.StatsVer, CMSketch: idx.CMSketch, PhysicalID: idx.PhysicalID} | ||
| newIndexHist.Histogram = *statistics.NewHistogram(idx.Histogram.ID, int64(float64(idx.Histogram.NDV)*statsNode.Selectivity), 0, 0, types.NewFieldType(mysql.TypeBlob), chunk.InitialCapacity, 0) | ||
|
|
||
| lowBucketIdx, highBucketIdx := 0, 0 | ||
| var totCnt int64 | ||
|
|
||
| // Bucket bound of index is encoded one, so we need to decode it if we want to calculate the fraction accurately. | ||
| // TODO: enhance its calculation. | ||
| // Now just remove the bucket that no range fell in. | ||
| for _, ran := range statsNode.Ranges { | ||
| lowBucketIdx = highBucketIdx | ||
| ranLowEncode, ranHighEncode, err = ran.Encode(sc, ranLowEncode, ranHighEncode) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| for ; highBucketIdx < idx.Histogram.Len(); highBucketIdx++ { | ||
| // Encoded value can only go to its next quickly. So ranHighEncode is actually range.HighVal's PrefixNext value. | ||
| // So the Bound should also go to its PrefixNext. | ||
| bucketLowerEncoded := idx.Histogram.Bounds.GetRow(highBucketIdx * 2).GetBytes(0) | ||
| if bytes.Compare(ranHighEncode, kv.Key(bucketLowerEncoded).PrefixNext()) < 0 { | ||
| break | ||
| } | ||
| } | ||
| for ; lowBucketIdx < highBucketIdx; lowBucketIdx++ { | ||
| bucketUpperEncoded := idx.Histogram.Bounds.GetRow(lowBucketIdx*2 + 1).GetBytes(0) | ||
| if bytes.Compare(ranLowEncode, bucketUpperEncoded) <= 0 { | ||
| break | ||
| } | ||
| } | ||
| if lowBucketIdx >= idx.Histogram.Len() { | ||
| break | ||
| } | ||
| for i := lowBucketIdx; i < highBucketIdx; i++ { | ||
| newIndexHist.Histogram.Bounds.AppendRow(idx.Histogram.Bounds.GetRow(i * 2)) | ||
| newIndexHist.Histogram.Bounds.AppendRow(idx.Histogram.Bounds.GetRow(i*2 + 1)) | ||
| totCnt += idx.Histogram.BucketCount(i) | ||
| newIndexHist.Histogram.Buckets = append(newIndexHist.Histogram.Buckets, statistics.Bucket{Repeat: idx.Histogram.Buckets[i].Repeat, Count: totCnt}) | ||
| newIndexHist.Histogram.Scalars = append(newIndexHist.Histogram.Scalars, idx.Histogram.Scalars[i]) | ||
| } | ||
| } | ||
| return newIndexHist, nil | ||
| } |
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