kvserver: opt-in "fast" external file snapshotting

pkg/ccl/storageccl/engineccl/shared_storage.go

@@ -50,6 +50,7 @@ func iterateReplicaKeySpansShared(
 	visitRangeDel func(start, end []byte, seqNum uint64) error,
 	visitRangeKey func(start, end []byte, keys []rangekey.Key) error,
 	visitSharedFile func(sst *pebble.SharedSSTMeta) error,
+	visitExternalFile func(sst *pebble.ExternalFile) error,
 ) error {
 	if !reader.ConsistentIterators() {
 		panic("reader must provide consistent iterators")
@@ -65,7 +66,7 @@ func iterateReplicaKeySpansShared(
 		ReplicatedBySpan:      desc.RSpan(),
 	})
 	span := spans[0]
-	return reader.ScanInternal(ctx, span.Key, span.EndKey, visitPoint, visitRangeDel, visitRangeKey, visitSharedFile)
+	return reader.ScanInternal(ctx, span.Key, span.EndKey, visitPoint, visitRangeDel, visitRangeKey, visitSharedFile, visitExternalFile)
 }
 
 func init() {

pkg/kv/kvserver/kvserverpb/raft.proto

@@ -196,6 +196,11 @@ message SnapshotRequest {
     // metadata present in the snapshot, but not file contents.
     bool shared_replicate = 12;
 
+    // If true, the snapshot could contain external files. Such files
+    // will have their metadata present in the snapshot but not the
+    // file contents.
+    bool external_replicate = 13;
+
     reserved 1, 4, 6, 7, 8, 9;
   }
 
@@ -242,6 +247,54 @@ message SnapshotRequest {
     uint64 size = 10;
   }
 
+  // ExternalTable represents one SSTable present in external storage.
+  // Intended to be the protobuf version of pebble.ExternalFile.
+  message ExternalTable {
+    // Used by the Pebble objstorage package to generate new blob storage drivers.
+    // Reserved for future use.
+    bytes locator = 1;
+
+    // ObjName is the unique name of this sstable on Locator.
+    string object_name = 2;
+
+    // Physical size of the sstable in bytes.
+    uint64 size = 3;
+
+    // StartKey is the loose, inclusive start key of the sstable.
+    bytes StartKey = 4;
+    // EndKey is the loose, end key of the sstable. Whether it is
+    // inclusive or exclusive is controlled by EndKeyIsInclusive.
+    bytes EndKey = 5;
+
+    // EndKeyIsInclusive is true if the EndKey is inclusive.
+    bool EndKeyIsInclusive = 6;
+
+    // HasPointKey denote whether this file contains point keys.
+    bool has_point_key = 7;
+
+    // HasRangeKey denote whether this file contains range keys.
+    bool has_range_key = 8;
+
+    // SyntheticPrefix will prepend this suffix to all keys in the file during
+    // iteration. Note that the backing file itself is not modified.
+    bytes synthetic_prefix = 9;
+
+    // SyntheticSuffix will replace the suffix of every key in the file during
+    // iteration. Note that the file itself is not modified, rather, every key
+    // returned by an iterator will have the synthetic suffix.
+    //
+    // SyntheticSuffix can only be used under the following conditions:
+    //  - the synthetic suffix must sort before any non-empty suffixes in the
+    //    backing sst (the entire sst, not just the part restricted to Bounds).
+    //  - the backing sst must not contain multiple keys with the same prefix.
+    bytes synthetic_suffix = 10;
+
+    // LSM level of the original sstable. This sstable will go into the same
+    // level in the destination LSM.
+    int32 level = 11;
+
+  }
+
   Header header = 1;
 
   // A BatchRepr. Multiple kv_batches may be sent across multiple request messages.
@@ -259,6 +312,8 @@ message SnapshotRequest {
   // flag must be set to true before any user keys are streamed.
   bool transition_from_shared_to_regular_replicate = 6;
 
+  repeated ExternalTable external_tables = 7 [(gogoproto.nullable) = false];
+
   reserved 3;
 }
 

pkg/kv/kvserver/rditer/replica_data_iter.go

@@ -446,6 +446,7 @@ var IterateReplicaKeySpansShared func(
 	visitRangeDel func(start, end []byte, seqNum uint64) error,
 	visitRangeKey func(start, end []byte, keys []rangekey.Key) error,
 	visitSharedFile func(sst *pebble.SharedSSTMeta) error,
+	visitExternalFile func(sst *pebble.ExternalFile) error,
 ) error
 
 // IterateOptions instructs how points and ranges should be presented to visitor

pkg/kv/kvserver/replica_command.go

@@ -3078,6 +3078,12 @@ var traceSnapshotThreshold = settings.RegisterDurationSetting(
 		"trace logged (set to 0 to disable);", 0,
 )
 
+var externalFileSnapshotting = settings.RegisterBoolSetting(
+	settings.SystemOnly,
+	"kv.snapshot.external_files.enabled",
+	"enables sending external files as metadata during a snapshot",
+	false)
+
 // followerSendSnapshot receives a delegate snapshot request and generates the
 // snapshot from this replica. The entire process of generating and transmitting
 // the snapshot is handled, and errors are propagated back to the leaseholder.
@@ -3157,7 +3163,28 @@ func (r *Replica) followerSendSnapshot(
 	// a snapshot for a non-system range. This allows us to send metadata of
 	// sstables in shared storage as opposed to streaming their contents. Keys
 	// in higher levels of the LSM are still streamed in the snapshot.
-	sharedReplicate := r.store.cfg.SharedStorageEnabled && snap.State.Desc.StartKey.AsRawKey().Compare(keys.TableDataMin) >= 0
+	nonSystemRange := snap.State.Desc.StartKey.AsRawKey().Compare(keys.TableDataMin) >= 0
+	sharedReplicate := r.store.cfg.SharedStorageEnabled && nonSystemRange
+
+	// Use external replication if we aren't using shared
+	// replication, are dealing with a non-system range, are on at
+	// least 24.1, and our store has external files.
+	externalReplicate := !sharedReplicate && nonSystemRange &&
+		r.store.ClusterSettings().Version.IsActive(ctx, clusterversion.V24_1) &&
+		externalFileSnapshotting.Get(&r.store.ClusterSettings().SV)
+	if externalReplicate {
+		start := snap.State.Desc.StartKey.AsRawKey()
+		end := snap.State.Desc.EndKey.AsRawKey()
+		total, _, external, err := r.store.StateEngine().ApproximateDiskBytes(start, end)
+		if err != nil {
+			log.Warningf(ctx, "could not determine if store has external bytes: %v", err)
+			externalReplicate = false
+		}
+
+		// Enable ExternalReplicate only if we have more
+		// external bytes than local bytes.
+		externalReplicate = external > (total - external)
+	}
 
 	// Create new snapshot request header using the delegate snapshot request.
 	header := kvserverpb.SnapshotRequest_Header{
@@ -3178,6 +3205,7 @@ func (r *Replica) followerSendSnapshot(
 		SenderQueueName:     req.SenderQueueName,
 		SenderQueuePriority: req.SenderQueuePriority,
 		SharedReplicate:     sharedReplicate,
+		ExternalReplicate:   externalReplicate,
 	}
 	newBatchFn := func() storage.WriteBatch {
 		return r.store.TODOEngine().NewWriteBatch()

pkg/kv/kvserver/replica_raftstorage.go

@@ -386,6 +386,7 @@ type IncomingSnapshot struct {
 	raftAppliedIndex kvpb.RaftIndex      // logging only
 	msgAppRespCh     chan raftpb.Message // receives MsgAppResp if/when snap is applied
 	sharedSSTs       []pebble.SharedSSTMeta
+	externalSSTs     []pebble.ExternalFile
 	doExcise         bool
 	// clearedSpans represents the key spans in the existing store that will be
 	// cleared by doing the Ingest*. This is tracked so that we can convert the
@@ -673,7 +674,7 @@ func (r *Replica) applySnapshot(
 	if inSnap.doExcise {
 		exciseSpan := desc.KeySpan().AsRawSpanWithNoLocals()
 		if ingestStats, err =
-			r.store.TODOEngine().IngestAndExciseFiles(ctx, inSnap.SSTStorageScratch.SSTs(), inSnap.sharedSSTs, exciseSpan); err != nil {
+			r.store.TODOEngine().IngestAndExciseFiles(ctx, inSnap.SSTStorageScratch.SSTs(), inSnap.sharedSSTs, inSnap.externalSSTs, exciseSpan); err != nil {
 			return errors.Wrapf(err, "while ingesting %s and excising %s-%s", inSnap.SSTStorageScratch.SSTs(), exciseSpan.Key, exciseSpan.EndKey)
 		}
 	} else {

pkg/kv/kvserver/spanset/batch.go

@@ -452,8 +452,9 @@ func (s spanSetReader) ScanInternal(
 	visitRangeDel func(start []byte, end []byte, seqNum uint64) error,
 	visitRangeKey func(start []byte, end []byte, keys []rangekey.Key) error,
 	visitSharedFile func(sst *pebble.SharedSSTMeta) error,
+	visitExternalFile func(sst *pebble.ExternalFile) error,
 ) error {
-	return s.r.ScanInternal(ctx, lower, upper, visitPointKey, visitRangeDel, visitRangeKey, visitSharedFile)
+	return s.r.ScanInternal(ctx, lower, upper, visitPointKey, visitRangeDel, visitRangeKey, visitSharedFile, visitExternalFile)
 }
 
 func (s spanSetReader) Close() {
@@ -788,6 +789,7 @@ func (s spanSetBatch) ScanInternal(
 	visitRangeDel func(start []byte, end []byte, seqNum uint64) error,
 	visitRangeKey func(start []byte, end []byte, keys []rangekey.Key) error,
 	visitSharedFile func(sst *pebble.SharedSSTMeta) error,
+	visitExternalFile func(sst *pebble.ExternalFile) error,
 ) error {
 	// Only used on Engine.
 	panic("unimplemented")