statistics, planner: make the content in HistColl.ColID2IdxIDs stable

cmd/explaintest/r/imdbload.result

@@ -286,7 +286,7 @@ IndexLookUp_7	1005030.94	root
 └─TableRowIDScan_6(Probe)	1005030.94	cop[tikv]	table:char_name	keep order:false
 trace plan target = 'estimation' select * from char_name where ((imdb_index = 'I') and (surname_pcode < 'E436')) or ((imdb_index = 'L') and (surname_pcode < 'E436'));
 CE_trace
-[{"table_name":"char_name","type":"Column Stats-Point","expr":"((imdb_index = 'I'))","row_count":0},{"table_name":"char_name","type":"Column Stats-Point","expr":"((imdb_index = 'L'))","row_count":0},{"table_name":"char_name","type":"Column Stats-Range","expr":"((id >= -9223372036854775808 and id <= 9223372036854775807))","row_count":4314864},{"table_name":"char_name","type":"Index Stats-Range","expr":"((imdb_index = 'I') and (surname_pcode < 'E436')) or ((imdb_index = 'L') and (surname_pcode < 'E436'))","row_count":0},{"table_name":"char_name","type":"Index Stats-Range","expr":"((surname_pcode < 'E436'))","row_count":1005030},{"table_name":"char_name","type":"Table Stats-Expression-CNF","expr":"`or`(`and`(`eq`(imdbload.char_name.imdb_index, 'I'), `lt`(imdbload.char_name.surname_pcode, 'E436')), `and`(`eq`(imdbload.char_name.imdb_index, 'L'), `lt`(imdbload.char_name.surname_pcode, 'E436')))","row_count":804024}]
+[{"table_name":"char_name","type":"Column Stats-Point","expr":"((imdb_index = 'I'))","row_count":0},{"table_name":"char_name","type":"Column Stats-Point","expr":"((imdb_index = 'L'))","row_count":0},{"table_name":"char_name","type":"Column Stats-Range","expr":"((id >= -9223372036854775808 and id <= 9223372036854775807))","row_count":4314864},{"table_name":"char_name","type":"Column Stats-Range","expr":"((surname_pcode < 'E436'))","row_count":1005030},{"table_name":"char_name","type":"Index Stats-Range","expr":"((imdb_index = 'I') and (surname_pcode < 'E436')) or ((imdb_index = 'L') and (surname_pcode < 'E436'))","row_count":0},{"table_name":"char_name","type":"Index Stats-Range","expr":"((surname_pcode < 'E436'))","row_count":1005030},{"table_name":"char_name","type":"Table Stats-Expression-CNF","expr":"`or`(`and`(`eq`(imdbload.char_name.imdb_index, 'I'), `lt`(imdbload.char_name.surname_pcode, 'E436')), `and`(`eq`(imdbload.char_name.imdb_index, 'L'), `lt`(imdbload.char_name.surname_pcode, 'E436')))","row_count":804024}]
 
 explain select * from char_name where ((imdb_index = 'V') and (surname_pcode < 'L3416'));
 id	estRows	task	access object	operator info
@@ -356,7 +356,7 @@ IndexLookUp_11	901.00	root
   └─TableRowIDScan_9	901.00	cop[tikv]	table:keyword	keep order:false
 trace plan target = 'estimation' select * from keyword where ((phonetic_code = 'R1652') and (keyword > 'ecg-monitor' and keyword < 'killers'));
 CE_trace
-[{"table_name":"keyword","type":"Column Stats-Point","expr":"((phonetic_code = 'R1652'))","row_count":23480},{"table_name":"keyword","type":"Column Stats-Range","expr":"((id >= -9223372036854775808 and id <= 9223372036854775807))","row_count":236627},{"table_name":"keyword","type":"Column Stats-Range","expr":"((keyword > 'ecg-monitor' and keyword < 'killers'))","row_count":44075},{"table_name":"keyword","type":"Index Stats-Point","expr":"((phonetic_code = 'R1652'))","row_count":23480},{"table_name":"keyword","type":"Index Stats-Range","expr":"((keyword > 'ecg-monitor' and keyword < 'killers'))","row_count":44036},{"table_name":"keyword","type":"Index Stats-Range","expr":"((keyword >= 'ecg-m' and keyword <= 'kille'))","row_count":44036},{"table_name":"keyword","type":"Index Stats-Range","expr":"((phonetic_code = 'R1652') and (keyword > 'ecg-monitor' and keyword < 'killers'))","row_count":901},{"table_name":"keyword","type":"Table Stats-Expression-CNF","expr":"`and`(`eq`(imdbload.keyword.phonetic_code, 'R1652'), `and`(`gt`(imdbload.keyword.keyword, 'ecg-monitor'), `lt`(imdbload.keyword.keyword, 'killers')))","row_count":901}]
+[{"table_name":"keyword","type":"Column Stats-Point","expr":"((phonetic_code = 'R1652'))","row_count":23480},{"table_name":"keyword","type":"Column Stats-Range","expr":"((id >= -9223372036854775808 and id <= 9223372036854775807))","row_count":236627},{"table_name":"keyword","type":"Column Stats-Range","expr":"((keyword > 'ecg-monitor' and keyword < 'killers'))","row_count":44075},{"table_name":"keyword","type":"Index Stats-Point","expr":"((phonetic_code = 'R1652'))","row_count":23480},{"table_name":"keyword","type":"Index Stats-Range","expr":"((keyword >= 'ecg-m' and keyword <= 'kille'))","row_count":44036},{"table_name":"keyword","type":"Index Stats-Range","expr":"((phonetic_code = 'R1652') and (keyword > 'ecg-monitor' and keyword < 'killers'))","row_count":901},{"table_name":"keyword","type":"Table Stats-Expression-CNF","expr":"`and`(`eq`(imdbload.keyword.phonetic_code, 'R1652'), `and`(`gt`(imdbload.keyword.keyword, 'ecg-monitor'), `lt`(imdbload.keyword.keyword, 'killers')))","row_count":901}]
 
 explain select * from cast_info where (nr_order is null) and (person_role_id = 2) and (note >= '(key set pa: Florida');
 id	estRows	task	access object	operator info

planner/core/find_best_task.go

@@ -1711,9 +1711,10 @@ func (ds *DataSource) crossEstimateRowCount(path *util.AccessPath, conds []expre
 	if len(ranges) == 0 || len(accessConds) == 0 || err != nil {
 		return 0, err == nil, corr
 	}
-	idxID, idxExists := ds.stats.HistColl.ColID2IdxID[colID]
-	if !idxExists {
-		idxID = -1
+	idxID := int64(-1)
+	idxIDs, idxExists := ds.stats.HistColl.ColID2IdxIDs[colID]
+	if idxExists && len(idxIDs) > 0 {
+		idxID = idxIDs[0]
 	}
 	rangeCounts, ok := getColumnRangeCounts(ds.ctx, colID, ranges, ds.tableStats.HistColl, idxID)
 	if !ok {

statistics/histogram.go

@@ -997,7 +997,7 @@ func (coll *HistColl) NewHistCollBySelectivity(sctx sessionctx.Context, statsNod
 		Columns:       make(map[int64]*Column),
 		Indices:       make(map[int64]*Index),
 		Idx2ColumnIDs: coll.Idx2ColumnIDs,
-		ColID2IdxID:   coll.ColID2IdxID,
+		ColID2IdxIDs:  coll.ColID2IdxIDs,
 		Count:         coll.Count,
 	}
 	for _, node := range statsNodes {

statistics/index.go

@@ -349,10 +349,21 @@ func (idx *Index) expBackoffEstimation(sctx sessionctx.Context, coll *HistColl,
 			count float64
 			err   error
 		)
-		if anotherIdxID, ok := coll.ColID2IdxID[colID]; ok && anotherIdxID != idx.Histogram.ID {
-			count, err = coll.GetRowCountByIndexRanges(sctx, anotherIdxID, tmpRan)
-		} else if col, ok := coll.Columns[colID]; ok && !col.IsInvalid(sctx, coll.Pseudo) {
+		if col, ok := coll.Columns[colID]; ok && !col.IsInvalid(sctx, coll.Pseudo) {
 			count, err = coll.GetRowCountByColumnRanges(sctx, colID, tmpRan)
+		} else if idxIDs, ok := coll.ColID2IdxIDs[colID]; ok && len(indexRange.LowVal) > 1 {
+			// Note the `len(indexRange.LowVal) > 1` condition here, it means we only recursively call
+			// `GetRowCountByIndexRanges()` when the input `indexRange` is a multi-column range. This
+			// check avoids infinite recursion.
+			for _, idxID := range idxIDs {
+				if idxID == idx.Histogram.ID {
+					continue
+				}
+				count, err = coll.GetRowCountByIndexRanges(sctx, idxID, tmpRan)
+				if err == nil {
+					break
+				}
+			}
 		} else {
 			continue
 		}

statistics/table.go

@@ -101,10 +101,10 @@ type HistColl struct {
 	Indices    map[int64]*Index
 	// Idx2ColumnIDs maps the index id to its column ids. It's used to calculate the selectivity in planner.
 	Idx2ColumnIDs map[int64][]int64
-	// ColID2IdxID maps the column id to index id whose first column is it. It's used to calculate the selectivity in planner.
-	ColID2IdxID map[int64]int64
-	Count       int64
-	ModifyCount int64 // Total modify count in a table.
+	// ColID2IdxIDs maps the column id to a list index ids whose first column is it. It's used to calculate the selectivity in planner.
+	ColID2IdxIDs map[int64][]int64
+	Count        int64
+	ModifyCount  int64 // Total modify count in a table.
 
 	// HavePhysicalID is true means this HistColl is from single table and have its ID's information.
 	// The physical id is used when try to load column stats from storage.
@@ -846,7 +846,7 @@ func (coll *HistColl) ID2UniqueID(columns []*expression.Column) *HistColl {
 	return newColl
 }
 
-// GenerateHistCollFromColumnInfo generates a new HistColl whose ColID2IdxID and IdxID2ColIDs is built from the given parameter.
+// GenerateHistCollFromColumnInfo generates a new HistColl whose ColID2IdxIDs and IdxID2ColIDs is built from the given parameter.
 func (coll *HistColl) GenerateHistCollFromColumnInfo(infos []*model.ColumnInfo, columns []*expression.Column) *HistColl {
 	newColHistMap := make(map[int64]*Column)
 	colInfoID2UniqueID := make(map[int64]int64, len(columns))
@@ -869,7 +869,7 @@ func (coll *HistColl) GenerateHistCollFromColumnInfo(infos []*model.ColumnInfo,
 	}
 	newIdxHistMap := make(map[int64]*Index)
 	idx2Columns := make(map[int64][]int64)
-	colID2IdxID := make(map[int64]int64)
+	colID2IdxIDs := make(map[int64][]int64)
 	for _, idxHist := range coll.Indices {
 		ids := make([]int64, 0, len(idxHist.Info.Columns))
 		for _, idxCol := range idxHist.Info.Columns {
@@ -883,10 +883,13 @@ func (coll *HistColl) GenerateHistCollFromColumnInfo(infos []*model.ColumnInfo,
 		if len(ids) == 0 {
 			continue
 		}
-		colID2IdxID[ids[0]] = idxHist.ID
+		colID2IdxIDs[ids[0]] = append(colID2IdxIDs[ids[0]], idxHist.ID)
 		newIdxHistMap[idxHist.ID] = idxHist
 		idx2Columns[idxHist.ID] = ids
 	}
+	for _, idxIDs := range colID2IdxIDs {
+		slices.Sort(idxIDs)
+	}
 	newColl := &HistColl{
 		PhysicalID:     coll.PhysicalID,
 		HavePhysicalID: coll.HavePhysicalID,
@@ -895,7 +898,7 @@ func (coll *HistColl) GenerateHistCollFromColumnInfo(infos []*model.ColumnInfo,
 		ModifyCount:    coll.ModifyCount,
 		Columns:        newColHistMap,
 		Indices:        newIdxHistMap,
-		ColID2IdxID:    colID2IdxID,
+		ColID2IdxIDs:   colID2IdxIDs,
 		Idx2ColumnIDs:  idx2Columns,
 	}
 	return newColl
@@ -1084,8 +1087,9 @@ func (coll *HistColl) getIndexRowCount(sctx sessionctx.Context, idxID int64, ind
 				colID = colIDs[rangePosition]
 			}
 			// prefer index stats over column stats
-			if idx, ok := coll.ColID2IdxID[colID]; ok {
-				count, err = coll.GetRowCountByIndexRanges(sctx, idx, []*ranger.Range{&rang})
+			if idxIDs, ok := coll.ColID2IdxIDs[colID]; ok && len(idxIDs) > 0 {
+				idxID := idxIDs[0]
+				count, err = coll.GetRowCountByIndexRanges(sctx, idxID, []*ranger.Range{&rang})
 			} else {
 				count, err = coll.GetRowCountByColumnRanges(sctx, colID, []*ranger.Range{&rang})
 			}