index paging and caching

[Martin Pool]

I'd also incline towards setting a limit on the overall cache size,
and then trying to get the right replacement policy within that.  This
is the thing that will have the strongest effect if it's too large,
and also the thing users could most reasonably potentially set.  It
may be (??) that the access pattern is quite different between file
and metafile indexes, and so we need to arrange different replacement
policies for them.

Can I encourage you to add a -Dindexcache that says for example the
overall hit and miss rate.

-- 
Martin