Expiration : can keys / values expire ?

[adr...@gmail.com]

Hello,

I'm wondering if there is key or data expiration semantic in scalaris.

In some dbms one can do :

ok = hanoidb:put(Tree, <<"foo">>, <<"bar">>, 2), % 2 sec

{ok, <<"bar">>} = hanoidb:get(Tree, <<"foo">>),

ok = timer:sleep(3000), % 3000 ms

not_found = hanoidb:get(Tree, <<"foo">>)

grep'ing for "expire" in scalaris' source I have only found dht_node_db_cache.erl

Is it an expiration thing like above ? (I don't think so) If yes I think the db_backend API needs some more function specs.

What do you think about such an expiration feature ?

Have fun

Pierre M.

[Nico Kruber]

Hi Pierre,
in Scalaris there is no such thing as key/data expiration.
You'd need to implement this feature in your application instead.

In general, I'm not quite sure whether a transactional datastore aiming for
consistent storage should provide that. Also I expect some difficulties
regarding distributed setups...


Nico

[adr...@gmail.com]

Le jeudi 14 novembre 2013 18:53:42 UTC+1, Nico Kruber a écrit :

On Thursday 14 Nov 2013 07:20:02 adr...@gmail.com wrote:
> Hello,
>

> (snip)

>
> What do you think about such an expiration feature ?
> Have fun
>
> Pierre M.

Hi Pierre,
in Scalaris there is no such thing as key/data expiration.
You'd need to implement this feature in your application instead.

In general, I'm not quite sure whether a transactional datastore aiming for
consistent storage should provide that. Also I expect some difficulties
regarding distributed setups...


Nico

 Hello Nico,

thank you for explaining.

I understand the feature can be implemented at the application level.

And it is good if it makes it simpler to have transactions in a distributed cluster.

Have fun

Pierre M.