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 >
