*: Make use of the upperBound of ticlient's kv_scan interface to ensu…

…re no overbound scan will happen (#8081)

ddl/delete_range.go

@@ -14,7 +14,6 @@
 package ddl
 
 import (
-	"bytes"
 	"encoding/hex"
 	"fmt"
 	"math"
@@ -154,7 +153,7 @@ func (dr *delRange) doTask(ctx sessionctx.Context, r util.DelRangeTask) error {
 		finish := true
 		dr.keys = dr.keys[:0]
 		err := kv.RunInNewTxn(dr.store, false, func(txn kv.Transaction) error {
-			iter, err := txn.Iter(oldStartKey, nil)
+			iter, err := txn.Iter(oldStartKey, r.EndKey)
 			if err != nil {
 				return errors.Trace(err)
 			}
@@ -164,10 +163,7 @@ func (dr *delRange) doTask(ctx sessionctx.Context, r util.DelRangeTask) error {
 				if !iter.Valid() {
 					break
 				}
-				finish = bytes.Compare(iter.Key(), r.EndKey) >= 0
-				if finish {
-					break
-				}
+				finish = false
 				dr.keys = append(dr.keys, iter.Key().Clone())
 				newStartKey = iter.Key().Next()
 

ddl/index.go

@@ -622,7 +622,7 @@ func (w *addIndexWorker) fetchRowColVals(txn kv.Transaction, taskRange reorgInde
 	// taskDone means that the added handle is out of taskRange.endHandle.
 	taskDone := false
 	oprStartTime := startTime
-	err := iterateSnapshotRows(w.sessCtx.GetStore(), w.priority, w.table, txn.StartTS(), taskRange.startHandle,
+	err := iterateSnapshotRows(w.sessCtx.GetStore(), w.priority, w.table, txn.StartTS(), taskRange.startHandle, taskRange.endHandle, taskRange.endIncluded,
 		func(handle int64, recordKey kv.Key, rawRow []byte) (bool, error) {
 			oprEndTime := time.Now()
 			w.logSlowOperations(oprEndTime.Sub(oprStartTime), "iterateSnapshotRows in fetchRowColVals", 0)
@@ -1207,16 +1207,30 @@ func allocateIndexID(tblInfo *model.TableInfo) int64 {
 // recordIterFunc is used for low-level record iteration.
 type recordIterFunc func(h int64, rowKey kv.Key, rawRecord []byte) (more bool, err error)
 
-func iterateSnapshotRows(store kv.Storage, priority int, t table.Table, version uint64, seekHandle int64, fn recordIterFunc) error {
+func iterateSnapshotRows(store kv.Storage, priority int, t table.Table, version uint64, startHandle int64, endHandle int64, endIncluded bool, fn recordIterFunc) error {
 	ver := kv.Version{Ver: version}
 
 	snap, err := store.GetSnapshot(ver)
 	snap.SetPriority(priority)
 	if err != nil {
 		return errors.Trace(err)
 	}
-	firstKey := t.RecordKey(seekHandle)
-	it, err := snap.Iter(firstKey, nil)
+	firstKey := t.RecordKey(startHandle)
+
+	// Calculate the exclusive upper bound
+	var upperBound kv.Key
+	if endIncluded {
+		if endHandle == math.MaxInt64 {
+			upperBound = t.RecordKey(endHandle).PrefixNext()
+		} else {
+			// PrefixNext is time costing. Try to avoid it if possible.
+			upperBound = t.RecordKey(endHandle + 1)
+		}
+	} else {
+		upperBound = t.RecordKey(endHandle)
+	}
+
+	it, err := snap.Iter(firstKey, upperBound)
 	if err != nil {
 		return errors.Trace(err)
 	}

ddl/reorg.go

@@ -304,7 +304,7 @@ func getTableRange(d *ddlCtx, tbl table.PhysicalTable, snapshotVer uint64, prior
 	startHandle = math.MinInt64
 	endHandle = math.MaxInt64
 	// Get the start handle of this partition.
-	err = iterateSnapshotRows(d.store, priority, tbl, snapshotVer, math.MinInt64,
+	err = iterateSnapshotRows(d.store, priority, tbl, snapshotVer, math.MinInt64, math.MaxInt64, true,
 		func(h int64, rowKey kv.Key, rawRecord []byte) (bool, error) {
 			startHandle = h
 			return false, nil

store/tikv/scan.go

@@ -98,6 +98,11 @@ func (s *Scanner) Next() error {
 		}
 
 		current := s.cache[s.idx]
+		if len(s.endKey) > 0 && kv.Key(current.Key).Cmp(kv.Key(s.endKey)) >= 0 {
+			s.eof = true
+			s.Close()
+			return nil
+		}
 		// Try to resolve the lock
 		if current.GetError() != nil {
 			// 'current' would be modified if the lock being resolved

structure/hash.go

@@ -238,7 +238,7 @@ func (t *TxStructure) HClear(key []byte) error {
 
 func (t *TxStructure) iterateHash(key []byte, fn func(k []byte, v []byte) error) error {
 	dataPrefix := t.hashDataKeyPrefix(key)
-	it, err := t.reader.Iter(dataPrefix, nil)
+	it, err := t.reader.Iter(dataPrefix, dataPrefix.PrefixNext())
 	if err != nil {
 		return errors.Trace(err)
 	}

table/tables/index.go

@@ -240,7 +240,7 @@ func (c *index) Delete(sc *stmtctx.StatementContext, m kv.Mutator, indexedValues
 
 // Drop removes the KV index from store.
 func (c *index) Drop(rm kv.RetrieverMutator) error {
-	it, err := rm.Iter(c.prefix, nil)
+	it, err := rm.Iter(c.prefix, c.prefix.PrefixNext())
 	if err != nil {
 		return errors.Trace(err)
 	}
@@ -270,7 +270,8 @@ func (c *index) Seek(sc *stmtctx.StatementContext, r kv.Retriever, indexedValues
 		return nil, false, errors.Trace(err)
 	}
 
-	it, err := r.Iter(key, nil)
+	upperBound := c.prefix.PrefixNext()
+	it, err := r.Iter(key, upperBound)
 	if err != nil {
 		return nil, false, errors.Trace(err)
 	}
@@ -284,7 +285,8 @@ func (c *index) Seek(sc *stmtctx.StatementContext, r kv.Retriever, indexedValues
 
 // SeekFirst returns an iterator which points to the first entry of the KV index.
 func (c *index) SeekFirst(r kv.Retriever) (iter table.IndexIterator, err error) {
-	it, err := r.Iter(c.prefix, nil)
+	upperBound := c.prefix.PrefixNext()
+	it, err := r.Iter(c.prefix, upperBound)
 	if err != nil {
 		return nil, errors.Trace(err)
 	}

table/tables/tables.go

@@ -782,7 +782,8 @@ func (t *tableCommon) buildIndexForRow(ctx sessionctx.Context, rm kv.RetrieverMu
 // IterRecords implements table.Table IterRecords interface.
 func (t *tableCommon) IterRecords(ctx sessionctx.Context, startKey kv.Key, cols []*table.Column,
 	fn table.RecordIterFunc) error {
-	it, err := ctx.Txn().Iter(startKey, nil)
+	prefix := t.RecordPrefix()
+	it, err := ctx.Txn().Iter(startKey, prefix.PrefixNext())
 	if err != nil {
 		return errors.Trace(err)
 	}
@@ -798,7 +799,6 @@ func (t *tableCommon) IterRecords(ctx sessionctx.Context, startKey kv.Key, cols
 	for _, col := range cols {
 		colMap[col.ID] = &col.FieldType
 	}
-	prefix := t.RecordPrefix()
 	defaultVals := make([]types.Datum, len(cols))
 	for it.Valid() && it.Key().HasPrefix(prefix) {
 		// first kv pair is row lock information.
@@ -912,7 +912,7 @@ func (t *tableCommon) RebaseAutoID(ctx sessionctx.Context, newBase int64, isSetS
 // Seek implements table.Table Seek interface.
 func (t *tableCommon) Seek(ctx sessionctx.Context, h int64) (int64, bool, error) {
 	seekKey := tablecodec.EncodeRowKeyWithHandle(t.physicalTableID, h)
-	iter, err := ctx.Txn().Iter(seekKey, nil)
+	iter, err := ctx.Txn().Iter(seekKey, t.RecordPrefix().PrefixNext())
 	if !iter.Valid() || !iter.Key().HasPrefix(t.RecordPrefix()) {
 		// No more records in the table, skip to the end.
 		return 0, false, nil

util/admin/admin.go

@@ -639,7 +639,10 @@ func rowWithCols(sessCtx sessionctx.Context, txn kv.Retriever, t table.Table, h
 // genExprs use to calculate generated column value.
 func iterRecords(sessCtx sessionctx.Context, retriever kv.Retriever, t table.Table, startKey kv.Key, cols []*table.Column,
 	fn table.RecordIterFunc, genExprs map[model.TableColumnID]expression.Expression) error {
-	it, err := retriever.Iter(startKey, nil)
+	prefix := t.RecordPrefix()
+	keyUpperBound := prefix.PrefixNext()
+
+	it, err := retriever.Iter(startKey, keyUpperBound)
 	if err != nil {
 		return errors.Trace(err)
 	}
@@ -651,7 +654,6 @@ func iterRecords(sessCtx sessionctx.Context, retriever kv.Retriever, t table.Tab
 
 	log.Debugf("startKey:%q, key:%q, value:%q", startKey, it.Key(), it.Value())
 	rowDecoder := makeRowDecoder(t, cols, genExprs)
-	prefix := t.RecordPrefix()
 	for it.Valid() && it.Key().HasPrefix(prefix) {
 		// first kv pair is row lock information.
 		// TODO: check valid lock

util/prefix_helper.go

@@ -26,7 +26,7 @@ import (
 
 // ScanMetaWithPrefix scans metadata with the prefix.
 func ScanMetaWithPrefix(retriever kv.Retriever, prefix kv.Key, filter func(kv.Key, []byte) bool) error {
-	iter, err := retriever.Iter(prefix, nil)
+	iter, err := retriever.Iter(prefix, prefix.PrefixNext())
 	if err != nil {
 		return errors.Trace(err)
 	}
@@ -56,7 +56,7 @@ func ScanMetaWithPrefix(retriever kv.Retriever, prefix kv.Key, filter func(kv.Ke
 // DelKeyWithPrefix deletes keys with prefix.
 func DelKeyWithPrefix(rm kv.RetrieverMutator, prefix kv.Key) error {
 	var keys []kv.Key
-	iter, err := rm.Iter(prefix, nil)
+	iter, err := rm.Iter(prefix, prefix.PrefixNext())
 	if err != nil {
 		return errors.Trace(err)
 	}