Re: [naviserver-devel] ns_set ... -persistent

[Jeff R. <dv...@di...>]

I don't know that people love it so much as that there is no exact 
replacement for the functionality.

I'm a big proponent of compatibility but shared sets as they previously 
existed are problematic.  I wouldn't be at all surprised if they are 
thread-unsafe to the point of being able to crash the server.

An alternative might be to provide equivalent functionality 
(order-preserving, multiple entries for keys, access by index or key or 
case-insensitive key) as a new nsv subcommand, perhaps 'nsv_multiset'.

Separately, I was experimenting with a performance enhancement to 
ns_sets, creating a hashtable mapping the keys to indexes.  There is a 
slight cost in memory and on the first lookup, but it should get to 
breakeven after only around 3 lookups on average, with decreasing 
amortized cost after that.  The difference is measurable and can be 
significant, as much as 4x faster on a large set.  However, that's 
measured on a very large set, 1000 keys;  and the real savings is pretty 
small, around 15 microseconds per lookup on average hardware.  Is that 
kind of micro-optimization worth the additional complexity?

-J

Gustaf Neumann wrote:
> Stephen,
>
> do you remember why you took out the -shared flag from ns_set?
>
> https://bitbucket.org/naviserver/naviserver/changeset/1cbaf1acc09436f2a1c56102269a8b7fab0be168
>
>
> it seems that some people love it. We have either to take it
> out of
> the documentation (and give sensible explanation) or
> reintroduce it in the code...
>
> -gustaf