Hi, All
Given ``hfile`` in ``hbase`` is immutable, I want to know the timestamp
like when the ``hfile`` is generated. Does ``hbase`` have API to allow
user-applications to know this? I  need to know in postCompact() stage.

As a first attempt, I have tried using
``StoreFile.getBulkLoadTimestamp()``. By following code snippet, I
constantly get ``NullPointerException``.
  public void postCompact(ObserverContext<RegionCoprocessorEnvironment> c,
Store store, StoreFile resultFile) {
    if(resultFile == null) {
        return;
    }
    int timestampLastCompact = resultFile.getBulkLoadTimestamp();
    ...
  }

Any ideas are appreciated. Thanks.
Yun

Hi Yun Peng

You want to know the creation time? I could see the getModificationTime()
api.  Internally it is used to get a store file with minimum timestamp.
I have not tried it out.  Let me know if it solves your purpose.
Just try it out.

Regards
Ram
> -----Original Message-----
> From: yun peng [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, October 17, 2012 1:55 AM
> To: [EMAIL PROTECTED]
> Subject: how to get the timestamp of hfile, like when it's generated.
>
> Hi, All
> Given ``hfile`` in ``hbase`` is immutable, I want to know the timestamp
> like when the ``hfile`` is generated. Does ``hbase`` have API to allow
> user-applications to know this? I  need to know in postCompact() stage.
>
> As a first attempt, I have tried using
> ``StoreFile.getBulkLoadTimestamp()``. By following code snippet, I
> constantly get ``NullPointerException``.
>   public void postCompact(ObserverContext<RegionCoprocessorEnvironment>
> c,
> Store store, StoreFile resultFile) {
>     if(resultFile == null) {
>         return;
>     }
>     int timestampLastCompact = resultFile.getBulkLoadTimestamp();
>     ...
>   }
>
> Any ideas are appreciated. Thanks.
> Yun

On Tue, Oct 16, 2012 at 9:06 PM, Ramkrishna.S.Vasudevan
<[EMAIL PROTECTED]> wrote:
> Hi Yun Peng
>
> You want to know the creation time? I could see the getModificationTime()
> api.  Internally it is used to get a store file with minimum timestamp.
> I have not tried it out.  Let me know if it solves your purpose.
> Just try it out.
>

To add to Rams' response, if you have a reader on the file, you can
get some of its attributes (which I believe come from metadata block
-- you should check the code) and you can iterate the metadata too
which has stuff first and last keys, average size, etc.  See here:
http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/io/hfile/HFile.Reader.html
 To look at a particular file's metadata, see the hfile tool at
"9.7.5.2.2. HFile Tool" in the reference guide.

St.Ack

Hi, Ram and Stack,
It works for me, after an initial try out. Though the name seems a bit
confusing, as hfile in hbase is immutable and not supposed to be "modified"
afterwards, -)
Regards,
Yun

On Wed, Oct 17, 2012 at 1:09 AM, Stack <[EMAIL PROTECTED]> wrote:

> On Tue, Oct 16, 2012 at 9:06 PM, Ramkrishna.S.Vasudevan
> <[EMAIL PROTECTED]> wrote:
> > Hi Yun Peng
> >
> > You want to know the creation time? I could see the getModificationTime()
> > api.  Internally it is used to get a store file with minimum timestamp.
> > I have not tried it out.  Let me know if it solves your purpose.
> > Just try it out.
> >
>
> To add to Rams' response, if you have a reader on the file, you can
> get some of its attributes (which I believe come from metadata block
> -- you should check the code) and you can iterate the metadata too
> which has stuff first and last keys, average size, etc.  See here:
>
> http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/io/hfile/HFile.Reader.html
>  To look at a particular file's metadata, see the hfile tool at
> "9.7.5.2.2. HFile Tool" in the reference guide.
>
> St.Ack
>