Function BenchmarkIteratePrefixSingleKey

iterator_test.go:271–337

go test -v -run=XXX -bench=BenchmarkIterate -benchtime=3s Benchmark with opt.Prefix set === goos: linux goarch: amd64 pkg: github.com/dgraph-io/badger BenchmarkIteratePrefixSingleKey/Key_lookups-4 10000 365539 ns/op --- BENCH: BenchmarkIteratePrefixSingleKey/Key_lookups-4 iterator_t

(b *testing.B)

//
// Only my laptop there's a 20% improvement in latency with ~80 files.
func BenchmarkIteratePrefixSingleKey(b *testing.B) {
	dir, err := ioutil.TempDir(".", "badger-test")
	y.Check(err)
	defer removeDir(dir)
	opts := getTestOptions(dir)
	opts.TableLoadingMode = options.LoadToRAM
	db, err := Open(opts)
	y.Check(err)
	defer db.Close()

	N := 100000 // Should generate around 80 SSTables.
	val := []byte("OK")
	bkey := func(i int) []byte {
		return []byte(fmt.Sprintf("%06d", i))
	}

	batch := db.NewWriteBatch()
	for i := 0; i < N; i++ {
		y.Check(batch.Set(bkey(i), val))
	}
	y.Check(batch.Flush())
	var lsmFiles int
	err = filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
		if strings.HasSuffix(path, ".sst") {
			lsmFiles++
		}
		if err != nil {
			return err
		}
		return nil
	})
	y.Check(err)
	b.Logf("LSM files: %d", lsmFiles)
	b.Logf("Key splits: %v", db.KeySplits(nil))
	b.Logf("Key splits with prefix: %v", db.KeySplits([]byte("09")))

	b.Logf("Outer b.N: %d", b.N)
	b.Run("Key lookups", func(b *testing.B) {
		b.Logf("Inner b.N: %d", b.N)
		for i := 0; i < b.N; i++ {
			key := bkey(rand.Intn(N))
			err := db.View(func(txn *Txn) error {
				opt := DefaultIteratorOptions
				// NOTE: Comment opt.Prefix out here to compare the performance
				// difference between providing Prefix as an option, v/s not. I
				// see a 20% improvement when there are ~80 SSTables.
				opt.Prefix = key
				opt.AllVersions = true

				itr := txn.NewIterator(opt)
				defer itr.Close()

				var count int
				for itr.Seek(key); itr.ValidForPrefix(key); itr.Next() {
					count++
				}
				if count != 1 {
					b.Fatalf("Count must be one key: %s. Found: %d", key, count)