Hello, >> I am currently trying to devise a way to index and retrieve some >> millions of objects according to their modification date/time. One of >> the problems I'm facing is that of index "granularity": I'd like to >> provide "to the second" granularity, >> > will there ever be more than item with the same key? >
Exactly, that's the problem. >> but for that I need some structure >> that lets me do that. So, the options I see are: >> - A timestamp-based >> > What do you mean by "timestamp" > Well, it could be a UNIX timestamp. >> BTree index - looks highly inefficient, as there >> will be many entries with only one element (probably almost all of >> them), >> > I have no idea what you mean by this. > That's the problem you've already mentioned above. So, in a relational DB i would do something like: SELECT * FROM table WHERE timestamp >= X AND timestamp <= Y Since I cannot do this with ZODB, I'd have to have a BTree, indexed by timestamp... however, as you said, if I want "to the second" granularity, I will rarely have two items with the same key (which makes it pretty useless). So, I was wondering if there is some data structure I can use for this, as this seems to be a pretty common use case. The first thing that comes to my mind is a tree with different levels - i.e year, month,day, hour, minute... with the leaves being sets of items. Thanks! Pedro -- José Pedro Ferreira Indico Team IT-UDS-AVC 513-R-0042 CERN, Geneva, Switzerland _______________________________________________ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org https://mail.zope.org/mailman/listinfo/zodb-dev
