It will be called 4 times whatever you annotated on the UDF if you are using released version of hive.
https://issues.apache.org/jira/browse/HIVE-4209 , which will be included in 0.12.0, will make that single UDF call by caching result. 2013/7/24 Sanjay Subramanian <sanjay.subraman...@wizecommerce.com>: > Thanks Jan > > I will mod my UDF and test it out > > I want to make sure I understand your words here > "The obvious condition is that it must always return the identical result > when called with same parameters." > > If I can make sure that a call to the web service is successful it will > always return same output for a given set of input > > F(x1,y1) ---->will always equal -----> z1 > > that’s what u mean right ? > > sanjay > > From: Jan Dolinár <dolik....@gmail.com> > Reply-To: "user@hive.apache.org" <user@hive.apache.org> > Date: Tuesday, July 23, 2013 12:35 PM > To: user <user@hive.apache.org> > > Subject: Re: Calling same UDF multiple times in a SELECT query > > Hi, > > If you use annotation, Hive should be able to optimize it to single call: > > @UDFType(deterministic = true) > > The obvious condition is that it must always return the identical result > when called with same parameters. > > Little bit more on this can be found in Mark Grovers post at > http://mark.thegrovers.ca/1/post/2012/06/how-to-write-a-hive-udf.html. > > Regards, > Jan > > > On Tue, Jul 23, 2013 at 9:25 PM, Nitin Pawar <nitinpawar...@gmail.com> > wrote: >> >> fucntion return values are not stored for repeat use of same (as per my >> understanding) >> >> I know you may have already thought about other approach as >> >> select a , if (call <-1, -1 call) as b from (select a, fooudf(a) as call >> from table >> >> >> >> >> On Wed, Jul 24, 2013 at 12:42 AM, Sanjay Subramanian >> <sanjay.subraman...@wizecommerce.com> wrote: >>> >>> Hi >>> >>> V r using version hive-exec-0.9.0-cdh4.1.2 in production >>> >>> I need to check and use the output from a UDF in a query to assign values >>> to 2 columns in a SELECT query >>> >>> Example >>> >>> SELECT >>> a, >>> IF(fooUdf(a) < -1 , -1, fooUdf(a)) as b, >>> IF(fooUdf(a) < -1 , fooUdf(a), 0) as c >>> FROM >>> my_hive_table >>> >>> >>> So will fooUdf be called 4 times ? Or once ? >>> >>> Why this is important is because in our case this UDF calls a web service >>> and I don't want so many calls to the service. >>> >>> Thanks >>> >>> sanjay >>> >>> >>> >>> CONFIDENTIALITY NOTICE >>> ====================== >>> This email message and any attachments are for the exclusive use of the >>> intended recipient(s) and may contain confidential and privileged >>> information. Any unauthorized review, use, disclosure or distribution is >>> prohibited. If you are not the intended recipient, please contact the sender >>> by reply email and destroy all copies of the original message along with any >>> attachments, from your computer system. If you are the intended recipient, >>> please be advised that the content of this message is subject to access, >>> review and disclosure by the sender's Email System Administrator. >> >> >> >> >> -- >> Nitin Pawar > > > > CONFIDENTIALITY NOTICE > ====================== > This email message and any attachments are for the exclusive use of the > intended recipient(s) and may contain confidential and privileged > information. Any unauthorized review, use, disclosure or distribution is > prohibited. If you are not the intended recipient, please contact the sender > by reply email and destroy all copies of the original message along with any > attachments, from your computer system. If you are the intended recipient, > please be advised that the content of this message is subject to access, > review and disclosure by the sender's Email System Administrator.
