enhance: Remove bf from datanode (#36367) (#37027)

Remove bf from datanode:
1. When watching vchannels, skip loading **flushed** segments's bf. For
generating merged bf, we need to keep loading **growing** segments's bf.
2. Bypass bloom filter checks for delete messages, directly writing to
L0 segments.
3. In version 2.4, when dropping a partition, marking segments as
dropped depends on having the full segment list in the DataNode. So, we
need to keep syncing the segments every 10 minutes.

issue: https://github.com/milvus-io/milvus/issues/34585

pr: https://github.com/milvus-io/milvus/pull/35902,
https://github.com/milvus-io/milvus/pull/36367,
https://github.com/milvus-io/milvus/pull/36592

---------

Signed-off-by: bigsheeper <yihao.dai@zilliz.com>

internal/datanode/data_sync_service.go

@@ -178,8 +178,11 @@ func initMetaCache(initCtx context.Context, storageV2Cache *metacache.StorageV2C
 		}
 	}
 
+	// growing segments's stats should always be loaded, for generating merged pk bf.
 	loadSegmentStats("growing", unflushed)
-	loadSegmentStats("sealed", flushed)
+	if !paramtable.Get().DataNodeCfg.SkipBFStatsLoad.GetAsBool() {
+		loadSegmentStats("sealed", flushed)
+	}
 
 	// use fetched segment info
 	info.Vchan.FlushedSegments = flushed
@@ -345,13 +348,22 @@ func newServiceWithEtcdTickler(initCtx context.Context, node *DataNode, info *da
 // NOTE: compactiable for event manager
 func newDataSyncService(initCtx context.Context, node *DataNode, info *datapb.ChannelWatchInfo, tickler *tickler) (*dataSyncService, error) {
 	// recover segment checkpoints
-	unflushedSegmentInfos, err := node.broker.GetSegmentInfo(initCtx, info.GetVchan().GetUnflushedSegmentIds())
-	if err != nil {
-		return nil, err
+	var (
+		err                   error
+		unflushedSegmentInfos []*datapb.SegmentInfo
+		flushedSegmentInfos   []*datapb.SegmentInfo
+	)
+	if len(info.GetVchan().GetUnflushedSegmentIds()) > 0 {
+		unflushedSegmentInfos, err = node.broker.GetSegmentInfo(initCtx, info.GetVchan().GetUnflushedSegmentIds())
+		if err != nil {
+			return nil, err
+		}
 	}
-	flushedSegmentInfos, err := node.broker.GetSegmentInfo(initCtx, info.GetVchan().GetFlushedSegmentIds())
-	if err != nil {
-		return nil, err
+	if len(info.GetVchan().GetFlushedSegmentIds()) > 0 {
+		flushedSegmentInfos, err = node.broker.GetSegmentInfo(initCtx, info.GetVchan().GetFlushedSegmentIds())
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	var storageCache *metacache.StorageV2Cache

internal/datanode/writebuffer/l0_write_buffer.go

@@ -135,6 +135,17 @@ func (wb *l0WriteBuffer) dispatchDeleteMsgs(groups []*inData, deleteMsgs []*msgs
 	})
 }
 
+func (wb *l0WriteBuffer) dispatchDeleteMsgsWithoutFilter(deleteMsgs []*msgstream.DeleteMsg, startPos, endPos *msgpb.MsgPosition) {
+	for _, msg := range deleteMsgs {
+		l0SegmentID := wb.getL0SegmentID(msg.GetPartitionID(), startPos)
+		pks := storage.ParseIDs2PrimaryKeys(msg.GetPrimaryKeys())
+		pkTss := msg.GetTimestamps()
+		if len(pks) > 0 {
+			wb.bufferDelete(l0SegmentID, pks, pkTss, startPos, endPos)
+		}
+	}
+}
+
 func (wb *l0WriteBuffer) BufferData(insertMsgs []*msgstream.InsertMsg, deleteMsgs []*msgstream.DeleteMsg, startPos, endPos *msgpb.MsgPosition) error {
 	wb.mut.Lock()
 	defer wb.mut.Unlock()
@@ -152,9 +163,15 @@ func (wb *l0WriteBuffer) BufferData(insertMsgs []*msgstream.InsertMsg, deleteMsg
 		}
 	}
 
-	// distribute delete msg
-	// bf write buffer check bloom filter of segment and current insert batch to decide which segment to write delete data
-	wb.dispatchDeleteMsgs(groups, deleteMsgs, startPos, endPos)
+	if paramtable.Get().DataNodeCfg.SkipBFStatsLoad.GetAsBool() {
+		// In Skip BF mode, datanode no longer maintains bloom filters.
+		// So, here we skip filtering delete entries.
+		wb.dispatchDeleteMsgsWithoutFilter(deleteMsgs, startPos, endPos)
+	} else {
+		// distribute delete msg
+		// bf write buffer check bloom filter of segment and current insert batch to decide which segment to write delete data
+		wb.dispatchDeleteMsgs(groups, deleteMsgs, startPos, endPos)
+	}
 
 	// update pk oracle
 	for _, inData := range groups {

pkg/util/paramtable/component_param.go

@@ -4317,7 +4317,8 @@ Setting this parameter too small causes the system to store a small amount of da
 		Key:          "dataNode.skip.BFStats.Load",
 		Version:      "2.2.5",
 		PanicIfEmpty: false,
-		DefaultValue: "false",
+		DefaultValue: "true",
+		Forbidden:    true, // The SkipBFStatsLoad is a static config that not allow dynamic refresh.
 	}
 	p.SkipBFStatsLoad.Init(base.mgr)