checking 'perform sort' option in 'sort' stage

tejaswini · Post by **tejaswini** » Tue Nov 21, 2006 10:22 pm

In a SORT stage, under stage properties we can mention keys on which the incoming data has to be sorted. Suppose i am sorting on key 1 & 2. Under input partitioning tab, I am mentioning hash partition on the same keys used for sorting. under input partitioning tab, there is a check box called 'perform sort'. What is the significance of checking this box? only if i check this box will the sort happen? on which condition we should check this box? please clarify......

suresh.narasimha · Post by **suresh.narasimha** » Wed Nov 22, 2006 2:01 am

Hi Tejaswini,

Every stage in Px which is having an input from another stage will have this check box option which is called as implicit/link sort(This option will not be enabled unless or until you select some partition mode). This means, if your input data has to be sorted (depends on your functional requirement) before it enters into some stage then you have can go for this implicit sort check box option. This will be good if your data volume is low. For high volumes of data it is recommended to use an external sort.

Regards,
Suresh N

Nageshsunkoji · Post by **Nageshsunkoji** » Wed Nov 22, 2006 3:06 am

Hi,
The following description given in Parallel Job Developers Guide ,
Perform Sort : Select this to specify that data coming in on the
link should be sorted. Select the column or columns to sort on
from the Available list.

Usually, it is very helpful, if you want to perform link sorting, that means if your data have less volume and if you don't want to use sort stage operator, then you can go for this option in link sorting. It is avilable in every stage, not only sort stage. you can find it in all stages input partitioning tabs.

tejaswini · Post by **tejaswini** » Wed Nov 22, 2006 5:04 am

hi,

In job already I am having a separate 'SORT' stage. Also I am sorting explicitly on the same keys on which I am partitioning in the same stage. Now should I check the perform sort option also for the sort to happen? In this scenario, checking and unchecking this option mean the same or different?

Nageshsunkoji · Post by **Nageshsunkoji** » Wed Nov 22, 2006 5:18 am

tejaswini wrote:hi,

In job already I am having a separate 'SORT' stage. Also I am sorting explicitly on the same keys on which I am partitioning in the same stage. Now should I check the perform sort option also for the sort to happen? In this scenario, checking and unchecking this option mean the same or different?

Hi,

I don't think so, is there any need to check-in this option, if you are already using a sort stage to perform sort. There is no need to select this option. You will get proper result without any problem.