Perfect - The readPoint / WriteNumber stuff looks like what I was looking for.
thanks! AZ On Apr 29, 2013, at 11:26 AM, ramkrishna vasudevan <[email protected]> wrote: > Check this out > http://www.slideshare.net/cloudera/3-learning-h-base-internals-lars-hofhansl-salesforce-final > > Regards > Ram > > > On Mon, Apr 29, 2013 at 7:59 PM, Aaron Zimmerman < > [email protected]> wrote: > >> Thanks J-D. I'm interested in learning how HBase handles MVCC - do you >> know of any resources explaining? I have data streaming into hbase around >> 6 million records a day, and I'm scanning the tables pretty much constantly >> with mapreduce jobs that rollup and store the data elsewhere. So I want to >> understand better exactly which rows are present in a given scan. >> >> If I create a scan that reads an entire region, I would expect a "read >> committed" level to lock that region during the read (which might take a >> few minutes). So what happens to the rows that are inserted during the >> scan? >> >> AZ >> >> >> On Apr 25, 2013, at 4:34 PM, Jean-Daniel Cryans <[email protected]> >> wrote: >> >>> Inline. >>> >>> J-D >>> >>> >>> On Thu, Apr 25, 2013 at 1:09 PM, Aaron Zimmerman < >>> [email protected]> wrote: >>> >>>> Hi, >>>> >>>> If a region is being written to, and a scanner takes a lease out on the >>>> region, what will happen to the writes? Is there a concept of >> "Transaction >>>> Isolation Levels"? >>>> >>> >>> There's MVCC, so reads can happen while someone else is writing. What you >>> should expect from HBase is "read committed". >>> >>> >>>> >>>> I don't see errors in Puts while the tables are being scanned? But it >>>> seems that I'm losing writes somewhere, is it possible the writes could >>>> fail silently? >>>> >>> >>> Is it temporary while you're scanning or there's really data missing at >>> the end of the day? The former might happen on some older HBase versions >>> while the latter should never happen unless you lower the durability >> level >>> yourself and have machine failures. >>> >>> J-D >> >>
