Yes, you are right. Should use COUNT_STAR in this case. COUNT will only check for the first field and will not count null (if the first field is null). That might sound wired when using COUNT on multiple fields relation, but this is how it works now.
Thanks, Daniel On Mon, Sep 16, 2013 at 12:38 PM, Prashant Kommireddi <prash1...@gmail.com>wrote: > There is another UDF called COUNT_STAR that counts nulls. This is a > documented behavior of COUNT in that it ignores null. > > http://pig.apache.org/docs/r0.11.1/func.html#count > > > On Mon, Sep 16, 2013 at 12:22 PM, Daniel Dai <da...@hortonworks.com> > wrote: > > > It is COUNT.java:105: > > if (t != null && t.size() > 0 && t.get(0) != null) > > > > Seems we don't count tuple with first field null. Not sure why this > happen > > but I would think it a bug. > > > > Thanks, > > Daniel > > > > > > On Sun, Sep 15, 2013 at 8:40 PM, centerqi hu <cente...@gmail.com> wrote: > > > > > The sample.txt file content: > > > > > > android,u1,taobao1 > > > android,u1,taobao1 > > > ,u2,taobao2 > > > > > > RR = LOAD '/user/www/udc/output/bugfind/sample.txt' USING > PigStorage(',') > > > as (platform, machineID, productID); > > > RB = GROUP RR BY (productID); > > > RES = FOREACH RB{ > > > ITEMUV = DISTINCT RR.machineID; > > > GENERATE flatten(group),COUNT(ITEMUV) AS UV,COUNT(RR) > AS > > > PV; > > > }; > > > DUMP RES; > > > > > > OUTPUT: > > > > > > (taobao1,1,2) > > > (taobao2,1,0) > > > > > > Why taobao2 the pv is 0, but uv is 1? > > > > > > I view? the source code of the COUNT function > > > > > > If the first column is null, cnt will not increase > > > > > > while (it.hasNext()){ > > > Tuple t = (Tuple)it.next(); > > > if (t != null && t.size() > 0 && t.get(0) != null ) > > > cnt++; > > > } > > > > > > -- > > > cente...@gmail.com|齐忠 > > > > > > > -- > > CONFIDENTIALITY NOTICE > > NOTICE: This message is intended for the use of the individual or entity > to > > which it is addressed and may contain information that is confidential, > > privileged and exempt from disclosure under applicable law. If the reader > > of this message is not the intended recipient, you are hereby notified > that > > any printing, copying, dissemination, distribution, disclosure or > > forwarding of this communication is strictly prohibited. If you have > > received this communication in error, please contact the sender > immediately > > and delete it from your system. Thank You. > > > -- CONFIDENTIALITY NOTICE NOTICE: This message is intended for the use of the individual or entity to which it is addressed and may contain information that is confidential, privileged and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, you are hereby notified that any printing, copying, dissemination, distribution, disclosure or forwarding of this communication is strictly prohibited. If you have received this communication in error, please contact the sender immediately and delete it from your system. Thank You.
