add test

levels.go

@@ -768,8 +768,7 @@ func containsPrefix(table *table.Table, prefix []byte) bool {
 		// In table iterator's Seek, we assume that key has timestamp in last 8 bytes. We set ts=0,
 		// so that we don't skip the key prefixed with prefix.
 		prefixWithTs := make([]byte, len(prefix)+8)
-		copy(prefixWithTs[:len(prefix)], prefix)
-		prefixWithTs = prefixWithTs[:cap(prefixWithTs)]
+		copy(prefixWithTs, prefix)
 		ti.Seek(prefixWithTs)
 		if bytes.HasPrefix(ti.Key(), prefix) {
 			return true

levels_test.go

@@ -17,7 +17,11 @@
 package badger
 
 import (
+	"fmt"
 	"math"
+	"math/rand"
+	"os"
+	"sort"
 	"testing"
 	"time"
 
@@ -838,3 +842,48 @@ func TestDropPrefixMoveBug(t *testing.T) {
 		require.NoError(t, db.lc.validate())
 	})
 }
+
+func TestTableContainsPrefix(t *testing.T) {
+	opts := table.Options{
+		LoadingMode:        options.LoadToRAM,
+		BlockSize:          4 * 1024,
+		BloomFalsePositive: 0.001,
+	}
+
+	buildTable := func(keys []string) *os.File {
+		filename := fmt.Sprintf("%s%s%d.sst", os.TempDir(), string(os.PathSeparator), rand.Uint32())
+		f, err := y.CreateSyncedFile(filename, true)
+		require.NoError(t, err)
+		b := table.NewTableBuilder(opts)
+		defer b.Close()
+
+		v := []byte("value")
+		sort.Slice(keys, func(i, j int) bool {
+			return keys[i] < keys[j]
+		})
+		for _, k := range keys {
+			b.Add(y.KeyWithTs([]byte(k), 1), y.ValueStruct{Value: v}, 0)
+			b.Add(y.KeyWithTs([]byte(k), 2), y.ValueStruct{Value: v}, 0)
+		}
+		_, err = f.Write(b.Finish())
+		require.NoError(t, err)
+		f.Close()
+		f, _ = y.OpenSyncedFile(filename, true)
+		return f
+	}
+
+	f := buildTable([]string{"key1", "key3", "key31", "key32", "key4"})
+	tbl, err := table.OpenTable(f, opts)
+	require.NoError(t, err)
+	defer tbl.DecrRef()
+
+	require.True(t, containsPrefix(tbl, []byte("key")))
+	require.True(t, containsPrefix(tbl, []byte("key1")))
+	require.True(t, containsPrefix(tbl, []byte("key3")))
+	require.True(t, containsPrefix(tbl, []byte("key32")))
+	require.True(t, containsPrefix(tbl, []byte("key4")))
+
+	require.False(t, containsPrefix(tbl, []byte("key0")))
+	require.False(t, containsPrefix(tbl, []byte("key2")))
+	require.False(t, containsPrefix(tbl, []byte("key5")))
+}