Re: Update statment on Hive

[Renata Ghisloti Duarte de Souza <rg...@linux.vnet.ibm.com>]

I got it. Makes total sense!
Thank you for your explanation.


On Fri, 2013-05-31 at 20:04 +0000, Sanjay Subramanian wrote:
> Hi
> Hive reads and writes to HDFSŠand by definition HDFS is write once and
> immutable after that.
> So like an RDBMS there is no concept of an update rows.
> However if u want to delete some records based on a criteria, yesterday
> there was a smart post about it, basically selecting the inverse and doing
> an INSERT OVERWRITE on the table
> 
> INSERT OVERWRITE TABLE will write to the Hive managed HDFS location of
> that table and "replace" all that is there with your latest
> 
> INSERT OVERWRITE DIRECTORY will write to your HDFS location of choice and
> "replace" all that is there with your latest. You can use this directory
> as LOCATION to which your PARTITION may point later
> 
> 
> Note that INSERT OVERWRITE TABLE will follow the field separator of the
> destination table that u specified while creating the table
> 
> However INSERT OVERWRITE DIRECTORY will have Hive's default "CtrlA" as the
> field separator ( I use 0.10.x)Šperhaps this is changed in 0.11 u need to
> verify
> 
> In summary , u have to look at updates and deletes very differently from
> RDBMS
> 
> Good luck
> 
> sanjay
> 
> 
> 
> 
> 
> On 5/31/13 12:27 PM, "Renata Ghisloti Duarte de Souza"
> <rg...@linux.vnet.ibm.com> wrote:
> 
> >Hello,
> >
> >I was wondering about the "update" statement on Hive. Is it something
> >Hive needs? Or can "insert overwrite" be always used instead?
> >
> >Thank you in advance for the clarification,
> >
> >Renata.
> >
> >
> >
> 
> 
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