Weirdly enough I find that I have to agree with Andrew. First, how do you get time in units smaller than a ms? Second clock skew becomes an issue. Third, which clock are you using? The client machine? The RS? And then how do you synchronize each of the RS to be within a ms of each other? Correct me if I’m wrong but NTP doesn’t give that close of a sync.
Sorry, but really, not a good idea. If you want this… you can store the temporal data as a column. Time really is relative. On May 25, 2014, at 12:53 AM, Stack <st...@duboce.net> wrote: > On Fri, May 23, 2014 at 5:27 PM, lars hofhansl <la...@apache.org> wrote: > >> We have discussed this in the past. It just came up again during an >> internal discussion. >> Currently we simply store a Java timestamp (millisec since epoch), i.e. we >> have ms resolution. >> >> We do have 8 bytes for the TS, though. Not enough to store nanosecs (that >> would only cover 2^63/10^9/3600/24/365.24 = 292.279 years), but enough for >> microseconds (292279 years). >> Should we just store he TS is microseconds? We could do that right now >> (and just keep the ms resolution for now - i.e. the us part would always be >> 0 for now). >> Existing data must be in ms of course, so we'd grandfather that in, but >> new tables could store by default in us. >> >> We'd need to make this configurable both the column family level and >> client level, so clients could still opt to see data in ms. >> >> Comments? Too much to bite off? >> >> -- Lars >> >> > I'm a fan. As Enis cites, HBASE-8927 has good discussion. No > configuration I'd say. Just move to the new regime (though I suppose we > should let you turn it off). > > I think it was Liu Shaohui (IIRC) who made a suggestion that had us put > together ms and nanos under a synchronized block stamping the ts on Cells > (left-shift the currentTimeMillis and fill in the bottom bytes with as much > of the nanos as fits; i.e. your micros). Rather than nanos/micros, we > could use a counter instead if a Cell arrives in the same ms. Would be > costly having all ops go via one code block to get 'time' across cores and > handlers. > > St.Ack
