add colon

Signed-off-by: Ben Ye <benye@amazon.com>

pkg/store/cache/cache.go

@@ -25,13 +25,6 @@ var (
  ulidSize = uint64(len(ulid.ULID{}))
 )
 
-type PostingsCodec string
-
-const (
- CodecHeaderSnappy PostingsCodec = "dvs" // As in "diff+varint+snappy".
- CodecHeaderStreamedSnappy PostingsCodec = "dss" // As in "diffvarint+streamed snappy".
-)
-
 // IndexCache is the interface exported by index cache backends.
 // Store operations do not support context.Context, deadlines need to be
 // supported by the backends themselves. This is because Set operations are
@@ -86,7 +79,8 @@ func (c cacheKey) string() string {
  // which would end up in wrong query results.
  lbl := c.key.(cacheKeyPostings)
  lblHash := blake2b.Sum256([]byte(lbl.Name + ":" + lbl.Value))
- return "P:" + c.block + ":" + base64.RawURLEncoding.EncodeToString(lblHash[0:])
+ // Add : at the end to force using a new cache key for postings.
+ return "P:" + c.block + ":" + base64.RawURLEncoding.EncodeToString(lblHash[0:]) + ":"
  case cacheKeySeries:
  return "S:" + c.block + ":" + strconv.FormatUint(uint64(c.key.(cacheKeySeries)), 10)
  default:

pkg/store/postings_codec.go

@@ -90,7 +90,7 @@ func estimateSnappyStreamSize(length int) int {
 
 func diffVarintSnappyStreamedEncode(p index.Postings, length int) ([]byte, error) {
  compressedBuf := bytes.NewBuffer(make([]byte, 0, estimateSnappyStreamSize(length)))
- if n, err := compressedBuf.WriteString(string(codecHeaderStreamedSnappy)); err != nil {
+ if n, err := compressedBuf.WriteString(codecHeaderStreamedSnappy); err != nil {
  return nil, fmt.Errorf("writing streamed snappy header")
  } else if n != len(codecHeaderStreamedSnappy) {
  return nil, fmt.Errorf("short-write streamed snappy header")