When using the deleteVersion method, the disk size increases. about iavl

[erikgrinaker]

This seems troubling that deleting data is causing .9MB (at least) of io writes. The size not being reclaimed makes sense, more data being written doesn't seem like it should be the case.

This isn't necessarily true. LevelDB is log-structured, so deleting a key basically appends an additional log entry like:

some_random_key: delete

Every database key is a node hash and thus takes up about 40 byte each. It's also possible that orphan/inner node churn amplifies this.

[enlight]

In my experience you'll need to compact the db after deleting old versions in order to actually reclaim disk space, leveldb has a CompactRange function you can call with an empty range to compact the whole db.

[ValarDragon]

This seems troubling that deleting data is causing .9MB (at least) of io writes. The size not being reclaimed makes sense, more data being written doesn't seem like it should be the case. I think something is probably wrong here, either from a theoretic perspective of the IAVL schemes versioning, or just a sub-optimal implementation. I also suspect this same problem is likely a significant contributor to cosmos/cosmos-sdk#2131

[tac0turtle]

this was removed in the last release