Hi,
I have a question regarding query performance for rows greater than a
timestamp. The use case is this:
I want to find all the rows in a key range that have changed after a certain
timestamp and upto a certain timestamp, i.e. exactly using this SCAN api:
Scan setTimeRange(long minStamp, long maxStamp)
Get versions of columns only within the specified timestamp range,
[minStamp, maxStamp)
Would this query go through all the rows in the key range or is there an
optimization that makes it faster.
I ask because I read about such an optimization in the following paper:
http://oss.csie.fju.edu.tw/~tzu98/Apache%20Hadoop%20Goes%20Realtime%20at%20Facebook.pdf
Here is the excerpt:
"For data stored in HBase that is time-series or contains a specific,
known timestamp, a special timestamp file selection algorithm
was added. Since time moves forward and data is rarely inserted
at a significantly later time than its timestamp, each HFile will
generally contain values for a fixed range of time. This
information is stored as metadata in each HFile and queries that
ask for a specific timestamp or range of timestamps will check if
the request intersects with the ranges of each file, skipping those
which do not overlap. "
This will work perfectly for my use case but I don't know if this optimization,
or any other for this use case, exists in the Apache HBase. The version of
Apache HBASE we are currently using is 0.92.1 but considering moving to 0.94.
Thanks,
Pankaj
