Re: Re-evaluate compaction defaults in 5.1/trunk

[Jeff Jirsa]

On 2024/12/09 17:33:09 Benedict wrote:
> I think it would make sense to support overriding the default FP in the UCS 
> parameters, so we can treat it as a direct replacement. Desiree FP is 
> directly related to sstable overlaps after all. 
> 
> Can you think of any other usability gaps like this?
> 

Without reading the code, the only other one that comes to mind is single 
sstable upleveling in LCS.

(The UCS docs talk about trying to forecast when to push sstables one extra 
level, but we saw in it's often the case that you can breach the fanout without 
any real overlaps, and simply re-leveling via metadata mutation could maintain 
that invariant easier than rewriting the whole table. It's possible UCS is 
doing this, too, but again, not obvious in the docs.)