colblk: add isObsolete bitmap to data block

Add an isObsolete bitmap to the colblk data block schema, encoding whether a
key is obsolete (i.e. shadowed by an identical point key or range deletion with
a higher sequence number).

Iteration-time filtering of obsolete keys is not yet implemented.

sstable/colblk/cockroach_test.go

@@ -339,7 +339,7 @@ func TestCockroachDataBlock(t *testing.T) {
  for w.Size() < targetBlockSize {
  ik := base.MakeInternalKey(keys[count], base.SeqNum(rng.Uint64n(uint64(base.SeqNumMax))), base.InternalKeyKindSet)
  kcmp := w.KeyWriter.ComparePrev(ik.UserKey)
- w.Add(ik, values[count], block.InPlaceValuePrefix(kcmp.PrefixEqual()), kcmp)
+ w.Add(ik, values[count], block.InPlaceValuePrefix(kcmp.PrefixEqual()), kcmp, false /* isObsolete */)
  count++
  }
  serializedBlock, _ := w.Finish(w.Rows(), w.Size())
@@ -415,7 +415,7 @@ func benchmarkCockroachDataBlockWriter(b *testing.B, keyConfig crdbtest.KeyConfi
  for w.Size() < targetBlockSize {
  ik := base.MakeInternalKey(keys[count], base.SeqNum(rng.Uint64n(uint64(base.SeqNumMax))), base.InternalKeyKindSet)
  kcmp := w.KeyWriter.ComparePrev(ik.UserKey)
- w.Add(ik, values[count], block.InPlaceValuePrefix(kcmp.PrefixEqual()), kcmp)
+ w.Add(ik, values[count], block.InPlaceValuePrefix(kcmp.PrefixEqual()), kcmp, false /* isObsolete */)
  count++
  }
  _, _ = w.Finish(w.Rows(), w.Size())
@@ -459,7 +459,7 @@ func benchmarkCockroachDataBlockIter(b *testing.B, keyConfig crdbtest.KeyConfig,
  for w.Size() < targetBlockSize {
  ik := base.MakeInternalKey(keys[count], base.SeqNum(rng.Uint64n(uint64(base.SeqNumMax))), base.InternalKeyKindSet)
  kcmp := w.KeyWriter.ComparePrev(ik.UserKey)
- w.Add(ik, values[count], block.InPlaceValuePrefix(kcmp.PrefixEqual()), kcmp)
+ w.Add(ik, values[count], block.InPlaceValuePrefix(kcmp.PrefixEqual()), kcmp, false /* isObsolete */)
  count++
  }
  serializedBlock, _ := w.Finish(w.Rows(), w.Size())

sstable/colblk/data_block.go

@@ -371,6 +371,10 @@ type DataBlockWriter struct {
  // isValueExternal is the column writer for the is-value-external bitmap
  // that indicates when a value is stored out-of-band in a value block.
  isValueExternal BitmapBuilder
+ // isObsolete is the column writer for the is-obsolete bitmap that indicates
+ // when a key is known to be obsolete/non-live (i.e., shadowed by another
+ // identical point key or range deletion with a higher sequence number).
+ isObsolete BitmapBuilder
 
  enc blockEncoder
  rows int
@@ -379,13 +383,12 @@ type DataBlockWriter struct {
  lastUserKeyTmp []byte
 }
 
-// TODO(jackson): Add an isObsolete bitmap column.
-
 const (
  dataBlockColumnTrailer = iota
  dataBlockColumnPrefixChanged
  dataBlockColumnValue
  dataBlockColumnIsValueExternal
+ dataBlockColumnIsObsolete
  dataBlockColumnMax
 )
 
@@ -403,6 +406,7 @@ func (w *DataBlockWriter) Init(schema KeySchema) {
  w.prefixSame.Reset()
  w.values.Init()
  w.isValueExternal.Reset()
+ w.isObsolete.Reset()
  w.rows = 0
  w.maximumKeyLength = 0
  w.lastUserKeyTmp = w.lastUserKeyTmp[:0]
@@ -416,6 +420,7 @@ func (w *DataBlockWriter) Reset() {
  w.prefixSame.Reset()
  w.values.Reset()
  w.isValueExternal.Reset()
+ w.isObsolete.Reset()
  w.rows = 0
  w.maximumKeyLength = 0
  w.lastUserKeyTmp = w.lastUserKeyTmp[:0]
@@ -445,6 +450,10 @@ func (w *DataBlockWriter) String() string {
  w.isValueExternal.WriteDebug(&buf, w.rows)
  fmt.Fprintln(&buf)
 
+ fmt.Fprintf(&buf, "%d: is-obsolete: ", len(w.Schema.ColumnTypes)+dataBlockColumnIsObsolete)
+ w.isObsolete.WriteDebug(&buf, w.rows)
+ fmt.Fprintln(&buf)
+
  return buf.String()
 }
 
@@ -457,12 +466,19 @@ func (w *DataBlockWriter) String() string {
 // The caller is required to pass this in because in expected use cases, the
 // caller will also require the same information.
 func (w *DataBlockWriter) Add(
- ikey base.InternalKey, value []byte, valuePrefix block.ValuePrefix, kcmp KeyComparison,
+ ikey base.InternalKey,
+ value []byte,
+ valuePrefix block.ValuePrefix,
+ kcmp KeyComparison,
+ isObsolete bool,
 ) {
  w.KeyWriter.WriteKey(w.rows, ikey.UserKey, kcmp.PrefixLen, kcmp.CommonPrefixLen)
  if kcmp.PrefixEqual() {
  w.prefixSame.Set(w.rows)
  }
+ if isObsolete {
+ w.isObsolete.Set(w.rows)
+ }
  w.trailers.Set(w.rows, uint64(ikey.Trailer))
  if valuePrefix.IsValueHandle() {
  w.isValueExternal.Set(w.rows)
@@ -493,6 +509,7 @@ func (w *DataBlockWriter) Size() int {
  off = w.prefixSame.InvertedSize(w.rows, off)
  off = w.values.Size(w.rows, off)
  off = w.isValueExternal.Size(w.rows, off)
+ off = w.isObsolete.Size(w.rows, off)
  off++ // trailer padding byte
  return int(off)
 }
@@ -532,6 +549,7 @@ func (w *DataBlockWriter) Finish(rows, size int) (finished []byte, lastKey base.
  w.enc.encode(rows, &w.prefixSame)
  w.enc.encode(rows, &w.values)
  w.enc.encode(rows, &w.isValueExternal)
+ w.enc.encode(rows, &w.isObsolete)
  finished = w.enc.finish()
 
  w.lastUserKeyTmp = w.lastUserKeyTmp[:0]
@@ -568,6 +586,9 @@ type DataBlockReader struct {
  // true, the value contains a ValuePrefix byte followed by an encoded value
  // handle indicating the value's location within the value block(s).
  isValueExternal Bitmap
+ // isObsolete is the column reader for the is-obsolete bitmap
+ // that indicates whether a key is obsolete/non-live.
+ isObsolete Bitmap
  // maximumKeyLength is the maximum length of a user key in the block.
  // Iterators may use it to allocate a sufficiently large buffer up front,
  // and elide size checks during iteration.
@@ -586,6 +607,7 @@ func (r *DataBlockReader) Init(schema KeySchema, data []byte) {
  r.prefixChanged = r.r.Bitmap(len(schema.ColumnTypes) + dataBlockColumnPrefixChanged)
  r.values = r.r.RawBytes(len(schema.ColumnTypes) + dataBlockColumnValue)
  r.isValueExternal = r.r.Bitmap(len(schema.ColumnTypes) + dataBlockColumnIsValueExternal)
+ r.isObsolete = r.r.Bitmap(len(schema.ColumnTypes) + dataBlockColumnIsObsolete)
  r.maximumKeyLength = binary.LittleEndian.Uint32(data[:dataBlockCustomHeaderSize])
 }
 

sstable/colblk/data_block_test.go

@@ -45,6 +45,11 @@ func TestDataBlock(t *testing.T) {
  return buf.String()
  case "write":
  for _, line := range strings.Split(td.Input, "\n") {
+ isObsolete := strings.HasSuffix(line, "obsolete")
+ if isObsolete {
+ line = strings.TrimSuffix(line, "obsolete")
+ }
+
  j := strings.IndexRune(line, ':')
  ik := base.ParseInternalKey(line[:j])
 
@@ -55,7 +60,7 @@ func TestDataBlock(t *testing.T) {
  vp = block.ValueHandlePrefix(kcmp.PrefixEqual(), 0)
  }
  v := []byte(line[j+1:])
- w.Add(ik, v, vp, kcmp)
+ w.Add(ik, v, vp, kcmp, isObsolete)
  sizes = append(sizes, w.Size())
  }
  fmt.Fprint(&buf, &w)
@@ -108,7 +113,7 @@ func benchmarkDataBlockWriter(b *testing.B, prefixSize, valueSize int) {
  ik := base.MakeInternalKey(keys[j], base.SeqNum(rng.Uint64n(uint64(base.SeqNumMax))), base.InternalKeyKindSet)
  kcmp := w.KeyWriter.ComparePrev(ik.UserKey)
  vp := block.InPlaceValuePrefix(kcmp.PrefixEqual())
- w.Add(ik, values[j], vp, kcmp)
+ w.Add(ik, values[j], vp, kcmp, false /* isObsolete */)
  j++
  }
  w.Finish(w.Rows(), w.Size())