Why not use gpssh to excute shell on each node? On Wed, Apr 5, 2017 at 3:11 PM, Cyrille Lintz <[email protected]> wrote:
> Hello, > > From the HDB guide ( > http://hdb.docs.pivotal.io/212/hawq/reference/sql/CREATE- > EXTERNAL-TABLE.html#topic1__section4), > I read about Web external tables > > *Note: ON ALL/HOST is deprecated when creating a readable external table, > as HAWQ cannot guarantee scheduling executors on a specific host. Instead, > use ON MASTER, ON <number>, or SEGMENT <virtual_segment> to specify which > segment instances will execute the command.* > > > In my opinion, if possible, we should re-introduce the ON ALL option for > the external WEB tables, > I am concerned with the option ON <number> in the external web table > definition. We have to use the number of current hosts. So if we expand the > cluster, we will have to change this external web table. > > - If we have a value smaller than the actual number of hosts, some rows > will miss. > - If we have a value greater than the actual number of hosts, some rows > will be duplicated. > > > If we add the option ON ALL: > > - it will help to monitor the spill files > - it will help to read the segment log files (see the commented DDL > hawq_toolkit._hawq_log_segment_ext in the file $GPHOME/share/postgresql) > > > I know that the option ON HOST and ON ALL were deprecated due to elastic > runtime in HAWQ 2.x. It is related to the Hadoop architecture. > > However, how could we execute once a shell on each host of the cluster via > an external web table? > In this case, we are not using Hadoop FS, but local FS. > > Thanks, > > > *Cyrille LINTZ*Advisory Solution Architect | Pivotal Europe South > Mobile: + 33 (0)6 11 48 71 10 | [email protected] > -- Thanks Hubert Zhang
