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From James Campbell <jacampb...@pivotal.io>
Subject Re: A question of HAWQ (update/delete)
Date Wed, 13 Jul 2016 16:40:44 GMT
One way an “delete” can be implemented in Hawq is to use partition-exchange.  It is ugly,
but it provides away of implement more of a batch update/delete.

In order to do this, you need partitioned tables.   For a delete, you select everything in
the target partition out less the row(s) that you don’t want into a new partitioned table.
  The new table has the correct data in it. You use the alter table command to execute a
partition exchange.

You can us this general approach to perform an update.

Generally, it is not a good design practice to use deletes with big data or in data warehouses.
 We don’t want to be trying to implement an OLTP system.  However, if there is a business
case to do this, it can be done in more of a batch fashion.

Jim Campbell
jacampbell@pivotal.io <mailto:jacampbell@pivotal.io>
O: 703-753-5970
M: 571-247-6511

On July 13, 2016 at 12:18:19 PM, Wales Wang (wormwang@yahoo.com.invalid) wrote:

Actian vectorH can support update , delete on HDFS  

Wales Wang  

在 2016-7-13,下午11:15,Vineet Goel <vvineet@apache.org> 写道:  

> Update and Delete is not supported yet, but it's in the future plan. There  
> is a JIRA on it I believe:  
> https://issues.apache.org/jira/browse/HAWQ-304  
> Out of curiosity, what specific scenario are you trying to solve that  
> requires update/delete ?  
> -Vineet  
> On Tue, Jul 12, 2016 at 7:10 PM, jinzhy <jinzhy@neusoft.com> wrote:  
>> hello everybody,  
>> Can HAWQ or Pivotal HD support 'delete' or 'update' operation in  
>> HDFS now?I can only create append only table in my computer。  
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