We've also upgraded to Hadoop 0.18.1 in one of the recent checkins. - Doug
On Tue, Sep 23, 2008 at 5:57 PM, Doug Judd <[EMAIL PROTECTED]> wrote: > I just finished a pretty major overhaul of the code. You can see the > commit at > http://github.com/nuggetwheat/hypertable/commit/c725ccc123ea77c87935e724d78d60d169486181 > The following two changes went in: > > 1. Compactions now happen by freezing the cell cache and installing a new > empty one. When the compaction completes, the frozen cell cache gets thrown > away. This change has had the effect of dramatically cleaning up the code, > which should help with keeping the code base stable. > > 2. The timestamp has been split out into a timestamp and a revision > number. The timestamp is the insertion time of the cell. It can be > auto-assigned or user-supplied, just like the old timestamps. You can now > insert cells out-of-order with respect to timestamps. The revision number > is used internally to implement MVCC and provides for snapshot isolation. > It is really intended to be internal use only and auto-assigned, except when > we build a transaction monitor which will assign revision numbers directly. > If the timestamp and the revision number are both left auto-assigned, then > they reference the same bytes in the key, so that you only get hit with > 8-bytes per cell overhead as opposed to 16 bytes. > > NOTE: The on-disk CellStore format has changed with this commit. In other > words, the latest code will not work with old databases. You'll have to > blow away the old ones and start fresh. > > Thanks goes to Josh Tayler for suggesting #1 and for pointing out the need > to separate the timestamp concept from the revision number concept. Next > I'm going to tackle the problem that Donald reported and I'll also verify > that Josh's commit log cleanup problem has gone away. > > - Doug > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Hypertable Development" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/hypertable-dev?hl=en -~----------~----~----~----~------~----~------~--~---
