Page Comparison

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1. DataNode subscribe the insert channel
2. Proxy receives a delete request, split into insert channels by primary keys
3. DataNode receives a delete request from the insert channel, save it in buffer, and write it into the delta channel
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   1. save deleted id into structure map<segID, list(id, ts)>
   1. DataNode receives a flush request, write out the deletions saved above
      1. deleted ids are saved into a separated Minio file with name "/by-dev/deltalog/collectionID/partitionID/segmentID/xxx"
   2. DataNode notifies IndexNode to building indexes
   3. finish

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