Embedded cache DB alternative

[pditommaso]

Bug report

Nextflow tasks metadata is stored into a local embedded key-value database based on LevelDB.

This provides good performance, however, the LevelDB store has some stability issues on specific hardware/file systems causing and represent blocking factor for those users. See for example: #2377, #403, #351 and #309

The goal of this issue is to explore the use of lmdbjava as alternative storage for nextflow tasks metadata

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[bentsherman]

I guess this one is resolved by the cloud cache #4097

I know we were also considering parquet, but parquet is a columnar storage format so wouldn't be a good fit for the task cache. Instead any cache backend should be a true key-value store or at least row-based.

[bentsherman]

Although I see you were looking into LMDB. That should be a good choice. I can look into it if you want

[pditommaso]

I gave a try in the past to Lmdb in the past I was not really convinced: weird API, native OS dependencies, also it does not even really really maintained any more.

Maybe we should give a try to thin wrapper over classic Sqlite or Duckbd.

[bentsherman]

That's too bad, LMDB seems to have really good performance. SQLite could be a good option. Probably not DuckDB though, since it is designed for OLAP. It could be useful to export a cache DB to DuckDB for downstream analytics, but not during the pipeline execution.

[pditommaso]

Only a benchmark can really tell