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HBase, mail # user - Mongo vs HBase


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Re: Mongo vs HBase
Fuad Efendi 2011-08-11, 13:53
Sorry for off topic, butŠ just as a sample to understand fundamental
difference:
1. "SELECT COUNT" will take few hours on MySQL InnoDB in most typical
cases, and _it_is_ implemented.

2. Same with HBase: full table scan. However, with MapReduce it might take
less time. Or, we can query Solr (Lily-way) to get number of records, but
data won't be absolutely correct.

Just as a sampleŠ
Of course, we can "transactionally" store number of records somewhere and
_kill_performance_.

Another solution is to use fixed-width records (similar to MyISAM) - but
data will be sparse etc.
Lily provides Hbase -based "Write Ahead Log", Hbase-based "Message Queue",
and Hbase -based "Secondary Index" (separate library); and it also
provides framework support to subscribe to a queue of messages.
--
Fuad Efendi
http://www.tokenizer.ca
On 11-08-11 4:13 AM, "Laurent Hatier" <[EMAIL PROTECTED]> wrote:

>Thanks all.
>
>i've seen that there is no limit with HBase. I mean the following
>statement
>: "SELECT ... FROM ... LIMIT 1". (Because there is this method with
>Mongo^^)
>Is it implemented ?
>
>2011/8/11 Jason Rutherglen <[EMAIL PROTECTED]>
>
>> Laurent,
>>
>> This could be implemented with Lucene, eg, HBASE-3529.  Contact me
>> offline if you are interested in pursuing that angle.
>>
>> Cheers.
>>
>> On Wed, Aug 10, 2011 at 10:02 AM, Laurent Hatier
>> <[EMAIL PROTECTED]> wrote:
>> > Hi all,
>> >
>> > I would like to know why MongoDB is faster than HBase to select items.
>> > I explain my case :
>> > I've inserted 4'000'000 lines into HBase and MongoDB and i must
>>calculate
>> > the geolocation with the IP. I calculate a Long number with the IP
>>and i
>> go
>> > to find it into the 4'000'000 lines.
>> > it's take 5 ms to select the right row with Mongo instead of HBase
>>takes
>> 5
>> > seconds.
>> > I think that the reason is the method : cur.limit(1) with MongoDB but
>>is
>> > there no function like this with HBase ?
>> >
>> > --
>> > Laurent HATIER
>> > Étudiant en 2e année du Cycle Ingénieur à l'EISTI
>> >
>>
>
>
>
>--
>Laurent HATIER
>Étudiant en 2e année du Cycle Ingénieur à l'EISTI