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From Ted Yu <yuzhih...@gmail.com>
Subject Re: What if I want to write another table in MasterObserver.preModifyColumnFamily ?
Date Wed, 08 Mar 2017 01:05:21 GMT
It seems the following hook is better for your use case:

  default void postModifyColumn(final
ObserverContext<MasterCoprocessorEnvironment> ctx,
      TableName tableName, HColumnDescriptor columnFamily) throws
IOException {}

since there is no guarantee that column family is modified at
time preModifyColumnFamily() is called.

Cheers

On Tue, Mar 7, 2017 at 4:43 PM, Xi Yang <alex.xi.yang@gmail.com> wrote:

> Requirement:
>
> I want to record every change of modify columnFamily by using
> preModifyColumnFamily().
> Now I have a table "my_ddl_log" which used to record the change of
> columnFamily. For example:
>
> If jack change the TTL of columnFamily "primary" in table "employee". Then
> we should add a put to "my_ddl_log" like this record:
> log:name= 'jack'
> log:updateTime= '2017-03-07 12:12 GMT-08:00'
> log:change= ''Change TTL of Table: employee ColumnFamily: primary'
>
> I try to use preModifyColumnFamily to do this stuff.
>
> Thanks,
> Alex
>
>
> 2017-03-07 12:12 GMT-08:00 Ted Yu <yuzhihong@gmail.com>:
>
> > Describing your use case would allow people to give better answer.
> >
> > What kind of data do you write to other table in preModifyColumnFamily()
> ?
> >
> > Cross server call within observer is not good idea.
> >
> > Take a look at ConnectionUtils.createShortCircuitConnection().
> >
> > Cheers
> >
> > On Tue, Mar 7, 2017 at 11:42 AM, Xi Yang <alex.xi.yang@gmail.com> wrote:
> >
> > >     All the articles I've ever seen are talking about add increment or
> > > change put/get status or pinrt out logs. what if I want to write some
> > data
> > > to another table in Observer? For
> > > example, MasterObserver.preModifyColumnFamily()? Seems Observer is
> > runing
> > > at server side, so use connection is unneccessary and might raise some
> > > problem.
> > >    I know this might be a stupid question, so if you can just give some
> > > links let me to learn without explain in email, I will be grateful to
> you
> > > for your help
> > >
> > > Thanks,
> > > Alex
> > >
> >
>

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