Rocksdb: How do range scan in rocksdb?
rocksdb supports prefix_extractor, namely supports range queries, but there is no get_range() like interface for us to call? so, how do I perform range scan? using Get()?
lanxuezaipiao
All 5 comments
You can do it through iterators. Create a iterator by using DB::NewIterator(), Seek to the smaller boundary of your range, keep doing next() and read key() until either you reach the larger boundary of your range or Valid() becomes false.
siying
on 17 Jul 2014
Does any way to get the count of total data? Or, is it possible?
yuchi518
on 4 Aug 2014
@yuchi518 RocksDB doesn't know number of all live keys. But we recently add a feature to estimate total number of keys: https://github.com/facebook/rocksdb/commit/f6784766db165188613f581afd40ba8fb90aa2cd if you just want an estimation.
siying
on 4 Aug 2014
@siying
Thank you for the information.
yuchi518
on 5 Aug 2014
Close the issue for now, feel free to reopen if the issue is not resolved.
yhchiang
on 5 Aug 2014
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Most helpful comment
You can do it through iterators. Create a iterator by using DB::NewIterator(), Seek to the smaller boundary of your range, keep doing next() and read key() until either you reach the larger boundary of your range or Valid() becomes false.