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HBase, mail # dev - Re: Questions about versions and timestamp


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Re: Questions about versions and timestamp
Ted Yu 2013-03-20, 23:01
A few pointers so that you can find the answer yourself:

http://hbase.apache.org/book.html
Take a look at 2.5.2.8. Managed Compactions and
http://hbase.apache.org/book.html#compaction

You can also use search-hadoop.com

e.g. 'Possible to delete a specific cell?'

Cheers

On Wed, Mar 20, 2013 at 3:55 PM, Benyi Wang <[EMAIL PROTECTED]> wrote:

> Hi,
>
> Please forgive me if my questions have been already asked and answered many
> times because I could not googled any of them.
>
> If I do the following commands in hbase shell,
>
> hbase(main):048:0> create "test_ts_ver", "data"
> 0 row(s) in 1.0550 seconds
>
> hbase(main):049:0> describe "test_ts_ver"
> DESCRIPTION                                          ENABLED
>
>  {NAME => 'test_ts_ver', FAMILIES => [{NAME => 'data true
>
>  ', BLOOMFILTER => 'NONE', REPLICATION_SCOPE => '0',
>
>   VERSIONS => '3', COMPRESSION => 'NONE', MIN_VERSIO
>
>  NS => '0', TTL => '2147483647', BLOCKSIZE => '65536
>
>  ', IN_MEMORY => 'false', BLOCKCACHE => 'true'}]}
>
> 1 row(s) in 0.0940 seconds
>
> hbase(main):052:0> put "test_ts_ver", "row_1", "data:name", "benyi_w", 100
> 0 row(s) in 0.0040 seconds
>
> hbase(main):053:0> put "test_ts_ver", "row_1", "data:name", "benyi_1", 110
> 0 row(s) in 0.0050 seconds
>
> hbase(main):054:0> put "test_ts_ver", "row_1", "data:name", "benyi_2", 120
> 0 row(s) in 0.0040 seconds
>
> hbase(main):055:0> put "test_ts_ver", "row_1", "data:name", "benyi_3", 130
> 0 row(s) in 0.0040 seconds
>
> hbase(main):056:0> put "test_ts_ver", "row_1", "data:name", "benyi_4", 140
> 0 row(s) in 0.0040 seconds
>
> hbase(main):057:0> get "test_ts_ver", "row_1", { TIMERANGE=>[0,200] }
> COLUMN                CELL
>
>  data:name            timestamp=140, value=benyi_4
>
> 1 row(s) in 0.0140 seconds
>
> hbase(main):058:0> get "test_ts_ver", "row_1", { TIMERANGE=>[0,200],
> VERSIONS=>5 }
> COLUMN                CELL
>
>  data:name            timestamp=140, value=benyi_4
>
>  data:name            timestamp=130, value=benyi_3
>
>  data:name            timestamp=120, value=benyi_2
>
> 3 row(s) in 0.0050 seconds
>
> So far so good. But if I try to get timestamp=100 or 110, I still can get
> them
>
> hbase(main):059:0> get "test_ts_ver", "row_1", { TIMESTAMP=> 100 }
> COLUMN                CELL
>
>  data:name            timestamp=100, value=benyi_w
>
> 1 row(s) in 0.0120 seconds
>
> hbase(main):060:0> get "test_ts_ver", "row_1", { TIMESTAMP=> 110 }
> COLUMN                CELL
>
>  data:name            timestamp=110, value=benyi_1
>
> 1 row(s) in 0.0060 seconds
>
> My questions:
>
> 1. When all those old versions will be removed?
> 2. Will compact or major_compact remove those old versions?
> 3. Is there a section/chapter talking about this behavior In HBase
> Reference Guide?
>
> Thanks.
>
> Ben
>