Re: question about BookKeeper Ledgers

[Flavio Junqueira]

Hi Dhruba, Ledgers are not named by the application currently. We simply assign an increasing identification number to a new ledger. Consequently, it is not possible to ask BK if ledger "foo" exists.  I don't think it would be difficult to add this feature, though. We keep the ledger metadata on ZooKeeper, and we can simply name the corresponding znodes  using the alias the application provides. In fact, one option would be to implement this alias scheme directly on the application using the same ZooKeeper installation.     Regarding the size of a ledger, we keep the entry count, but not the byte count currently. This is also an interesting feature we could consider adding. Cheers, -Flavio On Dec 17, 2010, at 7:44 AM, Dhruba Borthakur wrote: Hi folks, I have a few questions about BookKeeper APIs: 1. is there a way to atomically check and create a ledger, something similar to to the POSIX O_CREAT flag? I would like to create a ledger only if the ledger does not already exist. If it exists, then the createLedger call should fail. Is there a way to achieve this functionality? 2. Is there a way to find the current size of a ledger? thanks, dhruba -- Connect to me at http://www.facebook.com/dhruba flavio junqueira   research scientist   f...@yahoo-inc.com direct +34 93-183-8828   avinguda diagonal 177, 8th floor, barcelona, 08018, es phone (408) 349 3300    fax (408) 349 3301