Update operation in RocksDB client is not blind

[chenlx0]

Hi, I recently stress tested Rocksdb on ycsb, and I found that the update operation in RocksDB client would call 'Get' function before 'Put' function:

https://github.com/brianfrankcooper/YCSB/blob/ce3eb9ce51c84ee9e236998cdd2cefaeb96798a8/rocksdb/src/main/java/site/ycsb/db/rocksdb/RocksDBClient.java#L271

That makes update operation more like a 'Read-Modify-Write' operation. However, the YCSB paper pointed out that the workload A updates are different from 'Read-Modify-Write', it should be blind writes:

We also ran a “read-modify-write” workload that reflects the frequently used pattern of reading a record, modifying it, and writing the changes back to the database. This work- load is similar to workload A (50/50 read/write ratio) except that the updates are “read-modify-write” rather than blind writes.

Is it ok to remove Get operation in RocksDB updates ? thks.

[busbey]

it depends on how values are being encoded. the update should change just the fields present while leaving prior fields the same. if the current implementation stores all the fields for a given record in a single rocksdb entry, then it will need to read the existing entry to get the existing fields.

[chenlx0]

Thanks for your answers!