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From Anoop John <anoop.hb...@gmail.com>
Subject Re: Overwrite a row
Date Sun, 21 Apr 2013 07:39:20 GMT
You can use MultiRowMutationEndpoint for atomic op on multiple rows (within
same region)..


On Sun, Apr 21, 2013 at 5:55 AM, Ted Yu <yuzhihong@gmail.com> wrote:

> Here is code from 0.94 code base:
>
>   public void mutateRow(final RowMutations rm) throws IOException {
>     new ServerCallable<Void>(connection, tableName, rm.getRow(),
>         operationTimeout) {
>       public Void call() throws IOException {
>         server.mutateRow(location.getRegionInfo().getRegionName(), rm);
>         return null;
>
> where RowMutations has the following check:
>
>   private void internalAdd(Mutation m) throws IOException {
>     int res = Bytes.compareTo(this.row, m.getRow());
>     if(res != 0) {
>       throw new IOException("The row in the recently added Put/Delete " +
>           Bytes.toStringBinary(m.getRow()) + " doesn't match the original
> one " +
>           Bytes.toStringBinary(this.row));
>
> This means you need to issue multiple mutateRow() calls for different rows.
>
> I think you should consider the potential impact on performance due to this
> limitation.
>
> For advanced usage, take a look at MultiRowMutationEndpoint:
>
>  * This class demonstrates how to implement atomic multi row transactions
> using
>  * {@link HRegion#mutateRowsWithLocks(java.util.Collection,
> java.util.Collection)}
>  * and Coprocessor endpoints.
>
> Cheers
>
> On Sat, Apr 20, 2013 at 10:11 AM, Kristoffer Sjögren <stoffe@gmail.com
> >wrote:
>
> > Just to absolutely be clear, is this also true for a batch that span
> > multiple rows?
> >
> >
> > On Sat, Apr 20, 2013 at 2:42 PM, Ted Yu <yuzhihong@gmail.com> wrote:
> >
> > > Operations within each batch are atomic.
> > > They would either all succeed or all fail.
> > >
> > > Time stamps would all refer to the latest cell (KeyVal).
> > >
> > > Cheers
> > >
> > > On Apr 20, 2013, at 12:17 AM, Kristoffer Sjögren <stoffe@gmail.com>
> > wrote:
> > >
> > > > The schema is known beforehand so this is exactly what I need. Great!
> > > >
> > > > One more question. What guarantees does the batch operation have? Are
> > the
> > > > operations contained within each batch atomic? I.e. all mutations
> will
> > be
> > > > given the same timestamp? If something fails, all operation fail or
> can
> > > it
> > > > fail partially?
> > > >
> > > > Thanks for your help, much appreciated.
> > > >
> > > > Cheers,
> > > > -Kristoffer
> > > >
> > > >
> > > > On Sat, Apr 20, 2013 at 4:47 AM, Ted Yu <yuzhihong@gmail.com> wrote:
> > > >
> > > >> I don't know details about Kristoffer's schema.
> > > >> If all the column qualifiers are known a priori, mutateRow() should
> > > serve
> > > >> his needs.
> > > >>
> > > >> HBase allows arbitrary number of columns in a column family. If the
> > > schema
> > > >> is dynamic, mutateRow() wouldn't suffice.
> > > >> If the column qualifiers are known but the row is very wide (and a
> few
> > > >> columns are updated per call), performance would degrade.
> > > >>
> > > >> Just some factors to consider.
> > > >>
> > > >> Cheers
> > > >>
> > > >> On Fri, Apr 19, 2013 at 1:41 PM, Mohamed Ibrahim <
> > mibrahim@mibrahim.net
> > > >>> wrote:
> > > >>
> > > >>> Actually I do see it in the 0.94 JavaDocs (
> > > >>
> > >
> >
> http://hbase.apache.org/0.94/apidocs/org/apache/hadoop/hbase/client/HTable.html#mutateRow(org.apache.hadoop.hbase.client.RowMutations)
> > > >>> ),
> > > >>> so may be it was added in 0.94.6 even though the jira says fixed
in
> > > 0.95
> > > >> .
> > > >>> I haven't used it though, but it seems that's what you're looking
> > for.
> > > >>>
> > > >>> Sorry for confusion.
> > > >>>
> > > >>> Mohamed
> > > >>>
> > > >>>
> > > >>> On Fri, Apr 19, 2013 at 4:35 PM, Mohamed Ibrahim <
> > > mibrahim@mibrahim.net
> > > >>>> wrote:
> > > >>>
> > > >>>> It seems that 0.95 is not released yet, mutateRow won't be
a
> > solution
> > > >> for
> > > >>>> now. I saw it in the downloads and I thought it was released.
> > > >>>>
> > > >>>>
> > > >>>> On Fri, Apr 19, 2013 at 4:18 PM, Mohamed Ibrahim <
> > > >> mibrahim@mibrahim.net
> > > >>>> wrote:
> > > >>>>
> > > >>>>> Just noticed you want to delete as well. I think that's
supported
> > > >> since
> > > >>>>> 0.95 in mutateRow (
> > > >>
> > >
> >
> http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/client/HTable.html#mutateRow(org.apache.hadoop.hbase.client.RowMutations)
> > > >> ).
> > > >>>>> You can do multiple puts and deletes and they will be
performed
> > > >>> atomically.
> > > >>>>> So you can remove qualifiers and put new ones.
> > > >>>>>
> > > >>>>> Mohamed
> > > >>>>>
> > > >>>>>
> > > >>>>> On Fri, Apr 19, 2013 at 3:44 PM, Kristoffer Sjögren <
> > > stoffe@gmail.com
> > > >>>> wrote:
> > > >>>>>
> > > >>>>>> What would you suggest? I want the operation to be
atomic.
> > > >>>>>>
> > > >>>>>>
> > > >>>>>> On Fri, Apr 19, 2013 at 8:32 PM, Ted Yu <yuzhihong@gmail.com>
> > > wrote:
> > > >>>>>>
> > > >>>>>>> What is the maximum number of versions do you
allow for the
> > > >>> underlying
> > > >>>>>>> table ?
> > > >>>>>>>
> > > >>>>>>> Thanks
> > > >>>>>>>
> > > >>>>>>> On Fri, Apr 19, 2013 at 10:53 AM, Kristoffer Sjögren
<
> > > >>> stoffe@gmail.com
> > > >>>>>>>> wrote:
> > > >>>>>>>
> > > >>>>>>>> Hi
> > > >>>>>>>>
> > > >>>>>>>> Is it possible to completely overwrite/replace
a row in a
> single
> > > >>>>>> _atomic_
> > > >>>>>>>> action? Already existing columns and qualifiers
should be
> > removed
> > > >>> if
> > > >>>>>> they
> > > >>>>>>>> do not exist in the data inserted into the
row.
> > > >>>>>>>>
> > > >>>>>>>> The only way to do this is to first delete
the row then insert
> > > >> new
> > > >>>>>> data
> > > >>>>>>> in
> > > >>>>>>>> its place, correct? Or is there an operation
to do this?
> > > >>>>>>>>
> > > >>>>>>>> Cheers,
> > > >>>>>>>> -Kristoffer
> > > >>
> > >
> >
>

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