Batch writes

[amityahav]

it would be nice to support batch writes.
i want to be able to buffer all of my DB modifications that are appended to the WAL during a batch insert and only when the batch insert is completed flush it to the underlying file.

[roseduan]

I have thought about this before, but I need more time to design how to implement it.

[amityahav]

this can also optimize batch inserts in rosedb

[roseduan]

Here is my thought:

1. Add a function named PendingWrites(data []byte)
   • all new data will be maintained in WAL pendingWrites [][]byte
2. Add a function named WriteAll
   • write all data in pendingWrites
   • update blockNumber and blockSize
   • reset the pendingWrites in wal
   • return all ChunkPosition