Hi Gerald, I have verified against latest Phoenix code that this problem has been fixed. I have also checked Phoenix 4.13 release tags. Looks like all versions of 4.13 packages now include that fix. Would you mind getting the latest Phoenix-4.13 package and testing it again? Thank you!
Thanks, Maryann On Tue, May 8, 2018 at 12:24 PM, Gerald Sangudi <gsang...@23andme.com> wrote: > Hello, > > I'm running Phoenix 4.13 on AWS EMR and getting the following EXPLAIN plan: > > Table: > > *CREATE TABLE salted ( keyA BIGINT NOT NULL, keyB BIGINT NOT > NULL, val SMALLINT, CONSTRAINT pk PRIMARY KEY (keyA, > keyB))SALT_BUCKETS = 64;* > EXPLAIN: > > *EXPLAINSELECT /*+ USE_SORT_MERGE_JOIN */COUNT(*) cFROM salted t1 JOIN > salted t2ON (t1.keyB = t2.keyB)WHERE t1.keyA = 10AND t2.keyA = 20;* > > *+------------------------------------------------------------------------------+-----------------+-+| > PLAN | EST_BYTES_READ | > |+------------------------------------------------------------------------------+-----------------+-+| > SORT-MERGE-JOIN (INNER) TABLES > | null | || CLIENT > 64-CHUNK PARALLEL 64-WAY RANGE SCAN OVER SALTED [0,10] - [63,10] | null | > || SERVER FILTER BY FIRST KEY ONLY > | null | || CLIENT MERGE SORT > | null | || AND > (SKIP MERGE) | > null | || CLIENT 64-CHUNK PARALLEL 64-WAY RANGE SCAN OVER SALTED [0,20] > - [63,20] | null | || SERVER FILTER BY FIRST KEY ONLY > | null | || SERVER SORTED BY > [T2.KEYB] | null | || CLIENT > MERGE SORT | null | > || CLIENT AGGREGATE INTO SINGLE ROW > | null | > |+------------------------------------------------------------------------------+-----------------+-+* > > In the EXPLAIN output, I see "SERVER SORTED BY [T2.KEYB]". Is this sort > necessary? For both JOIN terms T1 and T2, the value of keyA, the leading > part of the primary key, is fixed. Furthermore, there is no corresponding > sort of T1.KEYB. > > When I EXPLAIN the same query on a non-salted table, neither T1.KEYB nor > T2.KEYB is re-sorted. I'm hoping the sort is unnecessary. If so, is there > an open ticket? I would be happy to file a ticket and to contribute to a > fix. I would appreciate any guidance. > > Thanks, > Gerald > >
