On Mon, Jan 26, 2009 at 5:55 PM, Alex Karasulu <[email protected]> wrote: > A transaction journal (a.k.a. transaction log) is used to rapidly persist > write operations arriving at the server before being processed. Local > transactions for these operations are opened to apply the change. This > allows the server to replay operations which did not complete due to some > interruption during processing. It also allows the server eventually to > apply changes and their side effects (like those from triggers), in the same > transaction which allows all to rollback together or to succeed together. > We need these things eventually even though they may not be critical right > now for replication.
It may be a way to implement local transactions in ADS. The TxLog will be seen as a 'buffer', or temporary storage, until the trans > > Journal file formats are simple, with indices into these files to track > those operations that have completed from those that have not. Journals are > not ideal for a search-able history retrieval system to be used for auditing > and snapshotting. The history CL requires many more indices and it's > information needs to be more structured. Conversely search-able CL is not > ideal as a transaction log since organizing the information and updating all > these indices requires disk operations which take too much time. > > We have to be clear on what we want as a set of requirements. If we're > going to implement a transaction journal/log here's what I'd like to see: > > 0). Very fast write of operation information to disk including any > information needed to rollback an operation. > 1). The journal should be the basis for implementing local transactions and > indices into it should be minimized for performance sake. > 2). The transaction log should be pruned asynchronously removing operations > that have been processed. These operations can then be pumped into the CL, > for audit history and snapshotting. > > WDYT? Please add more, I have more thoughts which I can add later. > > Alex > > On Mon, Jan 26, 2009 at 11:29 AM, Emmanuel Lecharny <[email protected]> > wrote: >> >> >> Just because I think it's easier to recover from a crashed LDIF file >> >> than from a crashed JDBM file :) >> > >> > Good point. However as you said we might want a separate journal using >> > something howl or the alternative that David Jencks pointed out being >> > using >> > by the AMQ folks. >> >> Well, we should not close doors at this point. I know nothing about >> howl, so I would like to see if we can use it. > > -- Regards, Cordialement, Emmanuel Lécharny www.iktek.com
