Hello, Any guidance or thoughts on the thread below?
Thanks, Gerald On Fri, May 18, 2018 at 11:39 AM, Gerald Sangudi <gsang...@23andme.com> wrote: > Maryann, > > Can Phoenix provide hash aggregation on the client side? Are there design > / implementation reasons not to, or should I file a ticket for this? > > Thanks, > Gerald > > On Fri, May 18, 2018 at 11:29 AM, Maryann Xue <maryann....@gmail.com> > wrote: > >> Hi Gerald, >> >> Phoenix does have hash aggregation. The reason why sort-based aggregation >> is used in your query plan is that the aggregation happens on the client >> side. And that is because sort-merge join is used (as hinted) which is a >> client driven join, and after that join stage all operations can only be on >> the client-side. >> >> >> Thanks, >> Marynn >> >> On Fri, May 18, 2018 at 10:57 AM, Gerald Sangudi <gsang...@23andme.com> >> wrote: >> >>> Hello, >>> >>> Does Phoenix provide hash aggregation? If not, is it on the roadmap, or >>> should I file a ticket? We have aggregation queries that do not require >>> sorted results. >>> >>> For example, this EXPLAIN plan shows a CLIENT SORT. >>> >>> *CREATE TABLE unsalted ( keyA BIGINT NOT NULL, keyB BIGINT >>> NOT NULL, val SMALLINT, CONSTRAINT pk PRIMARY KEY (keyA, >>> keyB));* >>> >>> >>> *EXPLAINSELECT /*+ USE_SORT_MERGE_JOIN */ t1.val v1, t2.val v2, COUNT(*) >>> c FROM unsalted t1 JOIN unsalted t2 ON (t1.keyA = t2.keyA) GROUP BY t1.val, >>> t2.val;+------------------------------------------------------------+-----------------+----------------+--+| >>> PLAN | EST_BYTES_READ | EST_ROWS_READ | >>> |+------------------------------------------------------------+-----------------+----------------+--+| >>> SORT-MERGE-JOIN (INNER) TABLES | null | null | >>> || CLIENT 1-CHUNK PARALLEL 1-WAY FULL SCAN OVER UNSALTED | null | null >>> | || AND | null | >>> null | || CLIENT 1-CHUNK PARALLEL 1-WAY FULL SCAN OVER UNSALTED | null >>> | null | || CLIENT SORTED BY [TO_DECIMAL(T1.VAL), T2.VAL] | >>> null | null | || CLIENT AGGREGATE INTO DISTINCT ROWS BY [T1.VAL, T2.VAL] >>> | null | null | >>> |+------------------------------------------------------------+-----------------+----------------+--+* >>> Thanks, >>> Gerald >>> >> >> >
