bq. you must have your customerId, timestamp in the rowkey since you query on it
Have you looked at this API in Scan ? public Scan setTimeRange(long minStamp, long maxStamp) Cheers On Fri, Nov 15, 2013 at 1:28 PM, Asaf Mesika <asaf.mes...@gmail.com> wrote: > The problem is that I do know my rowkey design, and it follows people's > best practice, but generates a really bad use case which I can't seem to > know how to solve yet. > > The rowkey as I said earlier is: > <customerId><bucket><timestampInMs><uniqueId> > So when ,for example, you have 1000 customer, and bucket ranges from 1 to > 16, you eventually end up with: > * 30k regions - What happens, as I presume: you start with one region > hosting ALL customers, which is just one. As you pour in more customers and > more data, the region splitting kicks in. So, after a while, you get to a > situation in which most regions hosts a specific customerId, bucket and > time duration. For example: customer #10001, bucket 6, 01/07/2013 00:00 - > 02/07/2013 17:00. > * Empty regions - the first really bad consequence of what I told before is > that when the time duration is over, no data will ever be written to this > region. and Worst - when the TTL you set (lets say 1 month) is over and > it's 03/08/2013, this region gets empty! > > The thing is that you must have your customerId, timestamp in the rowkey > since you query on it, but when you do, you will essentially get regions > which will not get any more writes to them, and after TTL become zombie > regions :) > > The second bad part of this rowkey design is that some customer will have > significantly less traffic than other customers, thus in essence their > regions will get written in a very slow rate compared with the high traffic > customer. When this happens on the same RS - bam: the slow region Puts are > causing the WAL Queue to get bigger over time, since its region never gets > to Max Region Size (256MB in our case) thus never gets flushed, thus stays > in the 1st WAL file. Until when? Until we hit max logs file permitted (32) > and then regions are flushed forcely. When this happen, we get about 100 > regions with 3k-3mb store files. You can imagine what happens next. > > The weirdest thing here is that this rowkey design is very common - nothing > fancy here, so in essence this phenomenon should have happened to a lot of > people - but from some reason, I don't see that much writing about it. > > Thanks! > > Asaf > > > > On Fri, Nov 15, 2013 at 3:51 AM, Jia Wang <ra...@appannie.com> wrote: > > > Then the case is simple, as i said "check your row key design, you can > find > > the start and end row key for each region, from which you can know why > your > > request with a specific row key doesn't hit a specified region" > > > > Cheers > > Ramon > > > > > > On Thu, Nov 14, 2013 at 8:47 PM, Asaf Mesika <asaf.mes...@gmail.com> > > wrote: > > > > > It's from the same table. > > > The thing is that some <customerId> simply have less data saved in > HBase, > > > while others have x50 (max) data. > > > I'm trying to check how people designed their rowkey around it, or had > > > other out-of-the-box solution for it. > > > > > > > > > > > > On Thu, Nov 14, 2013 at 12:06 PM, Jia Wang <ra...@appannie.com> wrote: > > > > > > > Hi > > > > > > > > Are the regions from the same table? If it was, check your row key > > > design, > > > > you can find the start and end row key for each region, from which > you > > > can > > > > know why your request with a specific row key doesn't hit a specified > > > > region. > > > > > > > > If the regions are for different table, you may consider to combine > > some > > > > cold regions for some tables. > > > > > > > > Thanks > > > > Ramon > > > > > > > > > > > > On Thu, Nov 14, 2013 at 4:59 PM, Asaf Mesika <asaf.mes...@gmail.com> > > > > wrote: > > > > > > > > > Hi, > > > > > > > > > > Have anyone ran into a case where a Region Server is hosting > regions, > > > in > > > > > which some regions are getting lots of write requests, and the rest > > > gets > > > > > maye 1/1000 of the rate of write requests? > > > > > > > > > > This leads to a situation where the HLog queue reaches its maxlogs > > > limit > > > > > since, those HLogs containing the puts from slow-write regions are > > > > "stuck" > > > > > until the region will flush. Since those regions barely make it to > > > their > > > > > 256MB flush limit (our configuration), they won't flush. The HLogs > > > queue > > > > > gets bigger due to the fast-write regions, until reaches the stress > > > mode > > > > of > > > > > "We have too many logs". > > > > > This in turn flushes out lots of regions, many of them (about 100) > > are > > > > > ultra small (10k - 3mb). After 3 rounds like this, the compaction > > queue > > > > > gets very big....in the end the region server drops dead, and this > > load > > > > > somehow is moved to another RS, ... > > > > > > > > > > We are running 0.94.7 with 30 RS. > > > > > > > > > > I was wondering how did people handled a mix of slow-write-rate and > > > > > high-write-rate of regions in 1 RS? I was thinking of writing a > > > customer > > > > > load balancer, which keeps tabs on the write request count and > > memstore > > > > > size, and move all the slow-write regions to 20% of cluster RS > > > dedicated > > > > to > > > > > slow regions, thus releasing the fast write regions to work freely. > > > > > > > > > > Since this issue is hammering our production, we're about to try to > > > > > shut-down the WAL, and risk losing some information in those > > slow-write > > > > > regions until we can come up with a better solution. > > > > > > > > > > Any advice would be highly appreciated. > > > > > > > > > > Oh - our rowkey is quite normal: > > > > > <customerId><bucket><Timestamp><uniqueId> > > > > > > > > > > Thanks! > > > > > > > > > > > > > > >
