hbase-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From lars hofhansl <la...@apache.org>
Subject Re: HBase timestamp consistency aross multiple region servers?
Date Fri, 14 Mar 2014 21:49:28 GMT
In addition to what Ted and Andrew said...

If cell A is updated after cell B *and* the application does not set any timestamps *and*
cell A and B are part of the same row (i.e. have the same row key) then the timestamp of cell
A will be greater then cell B's. If cells A and B are not related by row (or an alternate
split policy) there is no guarantee (outside of the precision you can get from NTP).

If you do not mind the plug... These blogs might help to clarify the issues:

-- Lars

 From: S. Zhou <myxjtu@yahoo.com>
To: "user@hbase.apache.org" <user@hbase.apache.org> 
Sent: Friday, March 14, 2014 1:45 PM
Subject: HBase timestamp consistency aross multiple region servers?

Here is what I am trying to figure out: in the same table,  if cell A is updated after cell
B, is it guaranteed that the time stamp of cell A is always bigger than the time stamp of
cell B, even cell A and cell B could be stored on different machines (therefore these two
machines might out of sync on time)?

The reason I am asking this question is: I want to use time stamp to order the updates by
time. These updates are issued from multiple machines. I was thinking to use global counter
(stored in a separated HBase table) but I guess that counter table might become a hot spot
since each update needs to update this table.

My general problem is: I want to sort the updates stored in Hbase from multiple machines.
Please let me know if you have good thoughts.

Thanks a lot
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message