ofriedma

1. No, for all implementations 2. Didn't investigate it has it's still under future to research - it depends on the memtable itself

[LOG-hashspdb-memory.txt](https://github.com/speedb-io/speedb/files/13307517/LOG-hashspdb-memory.txt) [LOG-skiplist-memory.txt](https://github.com/speedb-io/speedb/files/13307518/LOG-skiplist-memory.txt) At least from this log, there is a gap between the skiplist and our spdb hash, some memory is not transparent through the arena stats or the BlockFetcher...

Summary from the logs: SkipList memory information: 2023/11/08-16:23:32.972665 33053 [/db_impl/db_impl.cc:1138] --- Malloc STATS count=11986 memory=**3292MB** total=28017343 2023/11/08-16:23:32.972668 33053 [/db_impl/db_impl.cc:1141] Arena Stats: Arena total: 3402655080 2023/11/08-16:23:32.972789 33053 [/db_impl/db_impl.cc:1173] Total CacheAllocationUsage: 32654944...

Adding massif-visualizer screentshots of skip list compared to spdb memtable.  

@ColinIanKing please add a record to HISTORY.md