[jira] [Created] (HIVE-14257) CBO: Push Join through Groupby to trigger shuffle reductions

["Gopal V (JIRA)" <ji...@apache.org>]

Gopal V created HIVE-14257:
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             Summary: CBO: Push Join through Groupby to trigger shuffle reductions
                 Key: HIVE-14257
                 URL: https://issues.apache.org/jira/browse/HIVE-14257
             Project: Hive
          Issue Type: Improvement
          Components: CBO
            Reporter: Gopal V


Similar to the optimizations in hive, already which push aggregates through a join (hive.transpose.aggr.join=true).

{code}
select count(v) from (select d_year, count(ss_item_sk) as v from store_sales, date_dim where ss_sold_date_sk=d_Date_sk group by d_year) w, date_dim d where d.d_year = w.d_year and d_date_sk = 1;
{code}

currently produces an entire aggregate of all years before discarding all of that (because obviously, there's no data for d_date_sk=1;

This particular example is a simplified version of TPC-DS Query59's join condition, which can have a reduction in scans by applying the d_month_seq between 1185 and 1185 + 11 into the wss alias.



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