Hello, Whitney: please check the replies inline.
On Mon, Feb 4, 2013 at 8:47 AM, Whitney Sorenson <[email protected]>wrote: > Hey all, > > A couple questions about running BK stand-alone: > > 1) If I call openLedgerNoRecovery am I blocking writes or not? What are > the guarantees I lose - just ordering? Can I use this to essentially read / > tail an active ledger? > open a ledger using openLedgerNoRecovery doesn't block any writes to it. And you don't lose the ordering guarantee. You could use it to read/tail an active ledger, but please keep in mind that you need to call #readLastConfirmed to catch up to the latest confirmed entries added by the writer. And the entries you could read from an openLedgerNoRecovery ledger, is just between 0 and last confirmed. you could check: http://zookeeper.apache.org/bookkeeper/docs/r4.2.0/apidocs/org/apache/bookkeeper/client/BookKeeper.html#asyncOpenLedgerNoRecovery(long, org.apache.bookkeeper.client.BookKeeper.DigestType, byte[], org.apache.bookkeeper.client.AsyncCallback.OpenCallback, java.lang.Object) > > 2) How can I access BK's metadata so that I can determine a list of > ledgers, and which ledgers are closed/open? It doesn't appear in the client > documentation ( > http://zookeeper.apache.org/bookkeeper/docs/r4.2.0/apidocs/org/apache/bookkeeper/client/) > Is this not an intended operation? Are clients supposed to track ledger ids > on their own (we are currently doing this but it seems suboptimal) > > currently we don't expose the API for client. Is there any special case you are considering? We'd happy to expose it if necessary. Since most of the cases are working in following styles: a *standby* writer observes the *active* writer state, if the *active* writer failed, the *standby* writer would take over the responsibility, closed the ledger written by *active* writer, replayed the ledger and created a new ledger to write new entries. For now, clients needs to track ledger ids on their end. There is one proposal working on providing *named* ledgers on top of bookkeeper to ease user's experience tracking ledger ids. You could check : https://issues.apache.org/jira/browse/BOOKKEEPER-220 . And we are under discussion on whether to provide ledger name internally in bookkeeper for metadata access concerns. We'd like to hear your feedback on the usage of API and make it better. > Thank you; > > -Whitney Sorenson > HubSpot > >
