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Posted to dev@hbase.apache.org by Ramkrishna S Vasudevan <ra...@huawei.com> on 2011/05/06 06:15:26 UTC
Any documents available on the Scanners
Hi
There are different scanners in HBase.
Any documents available explaining the details on them and what scanner will
be used in what flow ?
Regards
Ram
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Re: Any documents available on the Scanners
Posted by Stack <st...@duboce.net>.
Over on the regionserver, we'll open a Scanner per file and one for
the MemStore. We'll then do a merge on all running Scanners to return
results. Content in files is sorted as it is in the MemStore so the
merge is straight-forward enough running over the results of
Iterations on each individual Scanner. A Scan runs over a Region. A
Region has ColumnFamilies/Stores. A Store has a MemStore and
StoreFiles. Each in essence implements an 'Iterator'. Perhaps this
is the levels you refer to? We don't have doc. of how this works.
You any good at reading source code?
Yours,
St.Ack
On Fri, May 6, 2011 at 3:54 AM, Ramkrishna S Vasudevan
<ra...@huawei.com> wrote:
> Hi
>
> Sorry for adding both dev and user group.
>
> What i meant is there are different levels of scanners.
>
> Memstore scanner when the scanning has to be done from Memstore.
> HFileScanner when the scanning has to be done from hfile.
>
> All are stored as the keyvalue heap .
>
> Now my reason for asking the question was,
> There are 1000 records. Assume 750 had been flushed explicitly and they
> have been moved to stores.
>
> Remaining 250 are yet to be flushed.
>
> Now I do a scan of the entire records, now how does region server reads the
> values from different levels,
> May be this may be a dumb question but any documents on the scanning logic
> may be really helpful for learners.
>
> Regards
> Ram
>
> ****************************************************************************
> ***********
> This e-mail and attachments contain confidential information from HUAWEI,
> which is intended only for the person or entity whose address is listed
> above. Any use of the information contained herein in any way (including,
> but not limited to, total or partial disclosure, reproduction, or
> dissemination) by persons other than the intended recipient's) is
> prohibited. If you receive this e-mail in error, please notify the sender by
> phone or email immediately and delete it!
>
>
> -----Original Message-----
> From: jdcryans@gmail.com [mailto:jdcryans@gmail.com] On Behalf Of
> Jean-Daniel Cryans
> Sent: Friday, May 06, 2011 9:49 AM
> To: user@hbase.apache.org
> Subject: Re: Any documents available on the Scanners
>
> (please don't cross-post to multiple lists, bcc'ed dev@ since this is
> really a user question)
>
> There's only 1 scanner in HBase, can you be more precise?
>
> J-D
>
> On Thu, May 5, 2011 at 9:15 PM, Ramkrishna S Vasudevan
> <ra...@huawei.com> wrote:
>> Hi
>>
>>
>>
>> There are different scanners in HBase.
>>
>> Any documents available explaining the details on them and what scanner
> will
>> be used in what flow ?
>>
>>
>>
>> Regards
>>
>> Ram
>>
>>
>>
>>
> ****************************************************************************
>> ***********
>> This e-mail and attachments contain confidential information from HUAWEI,
>> which is intended only for the person or entity whose address is listed
>> above. Any use of the information contained herein in any way (including,
>> but not limited to, total or partial disclosure, reproduction, or
>> dissemination) by persons other than the intended recipient's) is
>> prohibited. If you receive this e-mail in error, please notify the sender
> by
>> phone or email immediately and delete it!
>>
>>
>>
>>
>
>
RE: Any documents available on the Scanners
Posted by Ramkrishna S Vasudevan <ra...@huawei.com>.
Hi
Sorry for adding both dev and user group.
What i meant is there are different levels of scanners.
Memstore scanner when the scanning has to be done from Memstore.
HFileScanner when the scanning has to be done from hfile.
All are stored as the keyvalue heap .
Now my reason for asking the question was,
There are 1000 records. Assume 750 had been flushed explicitly and they
have been moved to stores.
Remaining 250 are yet to be flushed.
Now I do a scan of the entire records, now how does region server reads the
values from different levels,
May be this may be a dumb question but any documents on the scanning logic
may be really helpful for learners.
Regards
Ram
****************************************************************************
***********
This e-mail and attachments contain confidential information from HUAWEI,
which is intended only for the person or entity whose address is listed
above. Any use of the information contained herein in any way (including,
but not limited to, total or partial disclosure, reproduction, or
dissemination) by persons other than the intended recipient's) is
prohibited. If you receive this e-mail in error, please notify the sender by
phone or email immediately and delete it!
-----Original Message-----
From: jdcryans@gmail.com [mailto:jdcryans@gmail.com] On Behalf Of
Jean-Daniel Cryans
Sent: Friday, May 06, 2011 9:49 AM
To: user@hbase.apache.org
Subject: Re: Any documents available on the Scanners
(please don't cross-post to multiple lists, bcc'ed dev@ since this is
really a user question)
There's only 1 scanner in HBase, can you be more precise?
J-D
On Thu, May 5, 2011 at 9:15 PM, Ramkrishna S Vasudevan
<ra...@huawei.com> wrote:
> Hi
>
>
>
> There are different scanners in HBase.
>
> Any documents available explaining the details on them and what scanner
will
> be used in what flow ?
>
>
>
> Regards
>
> Ram
>
>
>
>
****************************************************************************
> ***********
> This e-mail and attachments contain confidential information from HUAWEI,
> which is intended only for the person or entity whose address is listed
> above. Any use of the information contained herein in any way (including,
> but not limited to, total or partial disclosure, reproduction, or
> dissemination) by persons other than the intended recipient's) is
> prohibited. If you receive this e-mail in error, please notify the sender
by
> phone or email immediately and delete it!
>
>
>
>
Re: Any documents available on the Scanners
Posted by Jean-Daniel Cryans <jd...@apache.org>.
(please don't cross-post to multiple lists, bcc'ed dev@ since this is
really a user question)
There's only 1 scanner in HBase, can you be more precise?
J-D
On Thu, May 5, 2011 at 9:15 PM, Ramkrishna S Vasudevan
<ra...@huawei.com> wrote:
> Hi
>
>
>
> There are different scanners in HBase.
>
> Any documents available explaining the details on them and what scanner will
> be used in what flow ?
>
>
>
> Regards
>
> Ram
>
>
>
> ****************************************************************************
> ***********
> This e-mail and attachments contain confidential information from HUAWEI,
> which is intended only for the person or entity whose address is listed
> above. Any use of the information contained herein in any way (including,
> but not limited to, total or partial disclosure, reproduction, or
> dissemination) by persons other than the intended recipient's) is
> prohibited. If you receive this e-mail in error, please notify the sender by
> phone or email immediately and delete it!
>
>
>
>
Re: Any documents available on the Scanners
Posted by Jean-Daniel Cryans <jd...@apache.org>.
(please don't cross-post to multiple lists, bcc'ed dev@ since this is
really a user question)
There's only 1 scanner in HBase, can you be more precise?
J-D
On Thu, May 5, 2011 at 9:15 PM, Ramkrishna S Vasudevan
<ra...@huawei.com> wrote:
> Hi
>
>
>
> There are different scanners in HBase.
>
> Any documents available explaining the details on them and what scanner will
> be used in what flow ?
>
>
>
> Regards
>
> Ram
>
>
>
> ****************************************************************************
> ***********
> This e-mail and attachments contain confidential information from HUAWEI,
> which is intended only for the person or entity whose address is listed
> above. Any use of the information contained herein in any way (including,
> but not limited to, total or partial disclosure, reproduction, or
> dissemination) by persons other than the intended recipient's) is
> prohibited. If you receive this e-mail in error, please notify the sender by
> phone or email immediately and delete it!
>
>
>
>