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Posted to issues@drill.apache.org by "Mehant Baid (JIRA)" <ji...@apache.org> on 2015/03/18 04:26:38 UTC
[jira] [Updated] (DRILL-2309) Selecting count(), avg() of nullable
columns causes wrong results
[ https://issues.apache.org/jira/browse/DRILL-2309?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Mehant Baid updated DRILL-2309:
-------------------------------
Summary: Selecting count(), avg() of nullable columns causes wrong results (was: 'null' is counted with subquery)
> Selecting count(), avg() of nullable columns causes wrong results
> -----------------------------------------------------------------
>
> Key: DRILL-2309
> URL: https://issues.apache.org/jira/browse/DRILL-2309
> Project: Apache Drill
> Issue Type: Bug
> Components: Execution - Data Types
> Affects Versions: 0.8.0
> Reporter: Chun Chang
> Assignee: Mehant Baid
> Priority: Critical
> Fix For: 0.9.0
>
> Attachments: DRILL-2309.patch
>
>
> #Thu Feb 19 18:40:10 EST 2015
> git.commit.id.abbrev=1ceddff
> The following query returns correct count involving columns that contains null value.
> {code}
> 0: jdbc:drill:schema=dfs.drillTestDirComplexJ> select tt.gbyi, count(tt.nul) from (select t.id, t.gbyi, t.fl, t.nul from `complex.json` t) tt group by tt.gbyi order by tt.gbyi;
> +------------+------------+
> | gbyi | EXPR$1 |
> +------------+------------+
> | 0 | 33580 |
> | 1 | 33317 |
> | 2 | 33438 |
> | 3 | 33535 |
> | 4 | 33369 |
> | 5 | 32990 |
> | 6 | 33661 |
> | 7 | 33130 |
> | 8 | 33362 |
> | 9 | 33364 |
> | 10 | 33229 |
> | 11 | 33567 |
> | 12 | 33379 |
> | 13 | 33045 |
> | 14 | 33305 |
> +------------+------------+
> {code}
> But if you add more aggregation to the query, the returned count is wrong (pay attention to the last column).
> {code}
> 0: jdbc:drill:schema=dfs.drillTestDirComplexJ> select tt.gbyi, sum(tt.id), avg(tt.fl), count(tt.nul) from (select t.id, t.gbyi, t.fl, t.nul from `complex.json` t) tt group by tt.gbyi order by tt.gbyi;
> +------------+------------+------------+------------+
> | gbyi | EXPR$1 | EXPR$2 | EXPR$3 |
> +------------+------------+------------+------------+
> | 0 | 33445554017 | 499613.0956877819 | 66943 |
> | 1 | 33209358334 | 500760.0252919893 | 66318 |
> | 2 | 33369118041 | 498091.82200273 | 66994 |
> | 3 | 33254533860 | 498696.5063226428 | 66683 |
> | 4 | 33393965595 | 501125.64656145993 | 66638 |
> | 5 | 33216885506 | 499961.32710397616 | 66439 |
> | 6 | 33380205950 | 498875.3923256599 | 66911 |
> | 7 | 33405849390 | 501093.43067788356 | 66666 |
> | 8 | 33136951190 | 498458.1044031481 | 66479 |
> | 9 | 33319291474 | 499967.5392457864 | 66643 |
> | 10 | 33339388887 | 499190.47462408233 | 66787 |
> | 11 | 33571590550 | 502095.86682194035 | 66863 |
> | 12 | 33437342090 | 501708.8141502653 | 66647 |
> | 13 | 33071800925 | 498896.453904129 | 66290 |
> | 14 | 33448664191 | 501487.4206955959 | 66699 |
> +------------+------------+------------+------------+
> [code}
> plan for the query returned the wrong result:
> {code}
> 0: jdbc:drill:schema=dfs.drillTestDirComplexJ> explain plan for select tt.gbyi, sum(tt.id), avg(tt.fl), count(tt.nul) from (select t.id, t.gbyi, t.fl, t.nul from `complex.json` t) tt group by tt.gbyi order by tt.gbyi;
> +------------+------------+
> | text | json |
> +------------+------------+
> | 00-00 Screen
> 00-01 Project(gbyi=[$0], EXPR$1=[$1], EXPR$2=[$2], EXPR$3=[$3])
> 00-02 SingleMergeExchange(sort0=[0 ASC])
> 01-01 SelectionVectorRemover
> 01-02 Sort(sort0=[$0], dir0=[ASC])
> 01-03 Project(gbyi=[$0], EXPR$1=[CASE(=($2, 0), null, $1)], EXPR$2=[CAST(/(CastHigh(CASE(=($4, 0), null, $3)), $4)):ANY], EXPR$3=[$5])
> 01-04 HashAgg(group=[{0}], agg#0=[$SUM0($1)], agg#1=[$SUM0($2)], agg#2=[$SUM0($3)], agg#3=[$SUM0($4)], EXPR$3=[$SUM0($5)])
> 01-05 HashToRandomExchange(dist0=[[$0]])
> 02-01 HashAgg(group=[{0}], agg#0=[$SUM0($1)], agg#1=[COUNT($1)], agg#2=[$SUM0($2)], agg#3=[COUNT($2)], EXPR$3=[COUNT()])
> 02-02 Project(gbyi=[$3], id=[$2], fl=[$1], nul=[$0])
> 02-03 Scan(groupscan=[EasyGroupScan [selectionRoot=/drill/testdata/complex_type/json/complex.json, numFiles=1, columns=[`gbyi`, `id`, `fl`, `nul`], files=[maprfs:/drill/testdata/complex_type/json/complex.json]]])
> {code}
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