Khurram Faraaz created DRILL-2849:
-------------------------------------
Summary: Difference in query results over CSV file created by
CTAS, compared to results over original CSV file
Key: DRILL-2849
URL: https://issues.apache.org/jira/browse/DRILL-2849
Project: Apache Drill
Issue Type: Bug
Components: Storage - Text & CSV
Affects Versions: 0.9.0
Environment: 64e3ec52b93e9331aa5179e040eca19afece8317 | DRILL-2611:
value vectors should report valid value count | 16.04.2015 @ 13:53:34 EDT
Reporter: Khurram Faraaz
Assignee: Steven Phillips
Different results are seen for the same query over CSV data file and another
CSV data file created by CTAS using the same CSV file.
Tests were executed on 4 node cluster on CentOS.
I got rid of the header information that is written by CTAS into the new CSV
file that CTAS creates, and then ran my queries over CTAS' CSV file.
{code}
query over uncompressed CSV file, deletions/deletions-00000-of-00020.csv
select count(cast(columns[0] as double)),max(cast(columns[0] as
double)),min(cast(columns[0] as double)),avg(cast(columns[0] as double)),
columns[7] from `deletions/deletions-00000-of-00020.csv` group by columns[7];
88 rows selected (6.893 seconds)
=================================================
query over CSV file that was created by CTAS. (input to CTAS was
deletions/deletions-00000-of-00020.csv)
Notice there is one more record returned.
select count(cast(columns[0] as double)),max(cast(columns[0] as
double)),min(cast(columns[0] as double)),avg(cast(columns[0] as double)),
columns[7] from `csvToCSV_00000_of_00020/0_0_0.csv` group by columns[7];
89 rows selected (6.623 seconds)
==================================================
query over compressed CSV file
select count(cast(columns[0] as double)),max(cast(columns[0] as
double)),min(cast(columns[0] as double)),avg(cast(columns[0] as double)),
columns[7] from `deletions-00000-of-00020.csv.gz` group by columns[7];
88 rows selected (10.526 seconds)
==================================================
In the below cases, the count and sum results are different when query is
executed over CSV file that was created by CTAS. ( this may explain why we see
the difference in results in the above queries ? )
0: jdbc:drill:> select count(cast(columns[0] as double)),max(cast(columns[0] as
double)),min(cast(columns[0] as double)),avg(cast(columns[0] as double)),
columns[7] from `deletions/deletions-00000-of-00020.csv` where columns[7] is
null group by columns[7];
+------------+------------+------------+------------+------------+
| EXPR$0 | EXPR$1 | EXPR$2 | EXPR$3 | EXPR$4 |
+------------+------------+------------+------------+------------+
| 252 | 1.362983396001E12 | 1.165768779027E12 | 1.293794515595635E12 |
null |
+------------+------------+------------+------------+------------+
1 row selected (6.013 seconds)
0: jdbc:drill:> select count(cast(columns[0] as double)),max(cast(columns[0] as
double)),min(cast(columns[0] as double)),avg(cast(columns[0] as double)),
columns[7] from `deletions-00000-of-00020.csv.gz` where columns[7] is null
group by columns[7];
+------------+------------+------------+------------+------------+
| EXPR$0 | EXPR$1 | EXPR$2 | EXPR$3 | EXPR$4 |
+------------+------------+------------+------------+------------+
| 252 | 1.362983396001E12 | 1.165768779027E12 | 1.293794515595635E12 |
null |
+------------+------------+------------+------------+------------+
1 row selected (8.899 seconds)
Notice that count and sum results are different (from those above) when query
is executed over the CSV file created by CTAS.
0: jdbc:drill:> select count(cast(columns[0] as double)),max(cast(columns[0] as
double)),min(cast(columns[0] as double)),avg(cast(columns[0] as double)),
columns[7] from `csvToCSV_00000_of_00020/0_0_0.csv` where columns[7] is null
group by columns[7];
+------------+------------+------------+------------+------------+
| EXPR$0 | EXPR$1 | EXPR$2 | EXPR$3 | EXPR$4 |
+------------+------------+------------+------------+------------+
| 245 | 1.349670663E12 | 1.165768779027E12 | 1.2930281335065144E12 |
null |
+------------+------------+------------+------------+------------+
1 row selected (5.736 seconds)
{code}
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