Yes, you need to dump/store xxx_OrderRes to kick off the job. You will see two MapReduce jobs corresponding to the first and second join.
Thanks, Daniel On 11/1/16, 10:52 AM, "mingda li" <limingda1...@gmail.com> wrote: >Dear Dai, > >Thanks for your reply. >What I want to do is to compare the two different order of join. The query >is as following: > >*Bad_OrderIn = JOIN inventory BY inv_item_sk, catalog_sales BY cs_item_sk;* >*Bad_OrderRes = JOIN Bad_OrderIn BY (cs_item_sk, cs_order_number), >catalog_returns BY (cr_item_sk, cr_order_number);* >*Dump or Store Bad_OrderRes;* > >*Good_OrderIn = JOIN catalog_returns BY (cr_item_sk, cr_order_number), >catalog_sales BY (cs_item_sk, cs_order_number);* >*Good_OrderRes = JOIN Good_OrderIn BY cs_item_sk, inventory BY > inv_item_sk;* >*Dump or Store Good_OrderRes;* > >Since Pig execute the query lazily, I think only by Dump or Store the >result, I can know the time of MapReduce Job, is it right? If it is, then I >need to count the time to Dump or Store the result as the time for the >different orders' join. > >Bests, >Mingda > > > >On Tue, Nov 1, 2016 at 10:39 AM, Daniel Dai <da...@hortonworks.com> wrote: > >> Hi, Mingda, >> >> Pig does not do join reordering and will execute the query as the way it >> is written. Note you can join multiple relations in one join statement. >> >> Do you want execution time for each join in your statement? I assume you >> are using regular join and running with MapReduce, every join statement >> will be a separate MapReduce job and the join runtime is the runtime for >> its MapReduce job. >> >> Thanks, >> Daniel >> >> >> >> On 10/31/16, 8:21 PM, "mingda li" <limingda1...@gmail.com> wrote: >> >> >Dear all, >> > >> >I am doing optimization for multiple join. I am not sure if Pig can decide >> >the join order in optimization layer. Does anyone know about this? Or Pig >> >just execute the query as the way it is written. >> > >> >And, I want to do the multiple way Join on different keys. Can the >> >following query work? >> > >> >Res = >> >JOIN >> >(JOIN catalog_sales BY cs_item_sk, inventory BY inv_item_sk) BY >> >(cs_item_sk, cs_order_number), catalog_returns BY (cr_item_sk, >> >cr_order_number); >> > >> >BTW, each time, I run the query, it is finished in one second. Is there a >> >way to see the execution time? I have set the pig.udf.profile=true. Where >> >can I find the time? >> > >> >Bests, >> >Mingda >>
