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Subject: Re: row filter - binary comparator at certain range
From: Michael Segel <msegel_hadoop@hotmail.com>
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Date: Mon, 21 Oct 2013 06:38:50 -0500
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To: user@hbase.apache.org

Sorry if this double posts... may have used the wrong email first.

On Oct 21, 2013, at 6:36 AM, Michael Segel <michael_segel@hotmail.com> =
wrote:

>=20
> Lets look at what you are trying to do...=20
>=20
> You want to take data where the key is a timestamp (long datatype)=20
> You append it to a salt value 1=3D10 or 0-9 your example doesn't =
say...=20
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> You have a couple of problems with your choice of a key...=20
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> First after your initial 10 splits, you will still end up with writing =
everything to the left side of the region.=20
> This means that when the region splits... all writes will still be to =
the left leaving your regions still 1/2 the size that they could be with =
the with the exception of your last set of salted regions. In this case =
10 which will grow and then split.=20
>=20
> Is this a bad thing? Maybe yes, maybe no.=20
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> The issue is that you will then have to write 10 queries with a start =
key and a stop key to get the range of your timestamp.=20
>=20
>=20
> That would work, however...=20
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> 1) Justify why you want/need to use a timestamp as a key for the row.
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> I'd say tell us more about the use case and why the access pattern.
>=20
> Salting is bad in that the salt is disassociated to the underlying =
key.
> Taking the key's hash, truncating it and preprending (if this is an =
actual word) to the key gives you a random key where if you know the =
rowkey, you can hash it.
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> My suggestion is that you rethink your key...=20
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> On Oct 20, 2013, at 11:31 PM, Tony Duan <duanjianmin@126.com> wrote:
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>> Alex Vasilenko <aa.vasilenko@...> writes:
>>=20
>>>=20
>>> Lars,
>>>=20
>>> But how it will behave, when I have salt at the beginning of the key =
to
>>> properly shard table across regions? Imagine row key of format
>>> salt:timestamp and rows goes like this:
>>> ...
>>> 1:15
>>> 1:16
>>> 1:17
>>> 1:23
>>> 2:3
>>> 2:5
>>> 2:12
>>> 2:15
>>> 2:19
>>> 2:25
>>> ...
>>>=20
>>> And I want to find all rows, that has second part (timestamp) in =
range
>>> 15-25. What startKey and endKey should be used?
>>>=20
>>> Alexandr Vasilenko
>>> Web Developer
>>> Skype:menterr
>>> mob: +38097-611-45-99
>>>=20
>>> 2012/2/9 lars hofhansl <lhofhansl@...>
>> Hi,
>> Alexandr Vasilenko
>> Have you ever resolved this issue?i am also facing this iusse.
>> i also want implement this functionality.
>> Imagine row key of format
>> salt:timestamp and rows goes like this:
>> ...
>> 1:15
>> 1:16
>> 1:17
>> 1:23
>> 2:3
>> 2:5
>> 2:12
>> 2:15
>> 2:19
>> 2:25
>> ...
>>=20
>> And I want to find all rows, that has second part (timestamp) in =
range
>> 15-25.
>>=20
>> Could you please tell me how you resolve this ?
>> thanks  in advance.
>>=20
>>=20
>> Tony duan
>>=20
>>=20
>=20
> The opinions expressed here are mine, while they may reflect a =
cognitive thought, that is purely accidental.=20
> Use at your own risk.=20
> Michael Segel
> michael_segel (AT) hotmail.com
>=20
>=20
>=20
>=20
>=20
>=20