can a transform function issue its own query, or does it only process the columns passed to it

stevejj

Hi,

 

As the subject states, can a transform function, ie a UDTF, issue its own query, or does it only work with the columns passed to it by the calling SELECT query.

 

I've looked through the transform examples and can't see anything which issues its own query, but the documentation seemed to imply that it can ... ie return a completely different table.

 

Thanks,

SruthiA

Hi,

 

  User Defined Transform function is a concept that is developed by vertica ithat lets you to create your own library functions that are written in either c++, Java or R which are difficult to be performed using SQL.

 

It works only for the columns passed to it by calling SELECT query. Based on the type of UDTF you create, the output you see is completely a different table.

 

Please go through the example in the following URL, it will give you a better idea about UDTF

 

 

 

https://my.vertica.com/docs/7.1.x/HTML/index.htm#Authoring/ExtendingHPVertica/UDx/DeployingAndUsingUserDefinedTransforms.htm%3FTocPath%3DExtending%2520HP%2520Vertica%7CDeveloping%2520User%2520Defined%2520Extensions%2520(UDxs)%7CDeveloping%2520a%2520User%2520Defined%2520Extension%2520in%2520C%252B%252B%7CDeveloping%2520a%2520User%2520Defined%2520Transform%2520Function%2520in%2520C%252B%252B%7C_____6

 

 

You can find the code related to the function mentioned in the above URL at the location 

 

cd /opt/vertica/sdk/examples/

 

in your vertica cluster

 

-Regards,

 Sruthi