ethdb/pebble: fix range compaction (#26771)

* ethdb/pebble: fix range compaction

* ethdb/pebble: add comment

ethdb/pebble/pebble.go

@@ -20,6 +20,7 @@
 package pebble
 
 import (
+ "bytes"
  "fmt"
  "runtime"
  "sync"
@@ -361,6 +362,17 @@ func (d *Database) Stat(property string) (string, error) {
 // is treated as a key after all keys in the data store. If both is nil then it
 // will compact entire data store.
 func (d *Database) Compact(start []byte, limit []byte) error {
+ // There is no special flag to represent the end of key range
+ // in pebble(nil in leveldb). Use an ugly hack to construct a
+ // large key to represent it.
+ // Note any prefixed database entry will be smaller than this
+ // flag, as for trie nodes we need the 32 byte 0xff because
+ // there might be a shared prefix starting with a number of
+ // 0xff-s, so 32 ensures than only a hash collision could touch it.
+ // https://github.com/cockroachdb/pebble/issues/2359#issuecomment-1443995833
+ if limit == nil {
+ limit = bytes.Repeat([]byte{0xff}, 32)
+ }
  return d.db.Compact(start, limit, true) // Parallelization is preferred
 }