[elephant-devel] Re: Re: sqite3 - always increase database size

[Robert L. Read]

On Tue, 2008-04-08 at 23:17 +0300, Alex Mizrahi wrote:
>  > Will garbage collector be added into elephant in the future?
> 
> I think so, I remember Ian Eslick mentioned it, but I don't know it it will 
> be *near* future -- it is quite challenging thing.
> perhaps Ian will clarify if he has ideas on this.

Yes, it will definitely be done, but not in the upcoming release.  I'm
pleased that people are asking about it; in general Ian and I are not
sure what features are most desired.

> 
>  > One more thing, do I still have use remove-kv with drop-pobject?
> 
> yes. if you'll just do drop-pobject but not remove-kv, you'll be able to 
> retrieve object from btree, but reading slot will cause slot-unbound error, 
> that way you'll know object isn't there :)
> at least this way documentation suggests, i didn't try it myself:

I don't understand why you would explicitly call remove-kv.  Without a
code example, I can't be sure precisely what is intended, but remove-kv
is a low-level API call for cursors and btrees directly.  If you are
using Ian's Persistent classes, I seriously doubt you would want to call
it directly --- and if you do have to for some reason, it is an
oversight on our part.

> 
> drop-pobject reclaims persistent object storage by unbinding
>    all persistent slot values.  It can also helps catch errors
>    where an object should be unreachable, but a reference still
>    exists elsewhere in the DB.  On access, the unbound slots
>    should flag an error in the application program.  IMPORTANT:
>    this function does not clear the cached object instance or any
>    serialized references still in the db.  Need a migration or GC
>    for that!  drop-instances is preferred as it implements the proper
>    behavior for indexed classes
> 
> 
> 
> 
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