Krystal created DRILL-4735:
------------------------------
Summary: Count(dir0) on parquet returns 0 result
Key: DRILL-4735
URL: https://issues.apache.org/jira/browse/DRILL-4735
Project: Apache Drill
Issue Type: Bug
Components: Query Planning & Optimization, Storage - Parquet
Affects Versions: 1.6.0, 1.7.0
Reporter: Krystal
Selecting a count of dir0, dir1, etc against a parquet directory returns 0 rows.
select count(dir0) from `min_max_dir`;
+---------+
| EXPR$0 |
+---------+
| 0 |
+---------+
select count(dir1) from `min_max_dir`;
+---------+
| EXPR$0 |
+---------+
| 0 |
+---------+
If I put both dir0 and dir1 in the same select, it returns expected result:
select count(dir0), count(dir1) from `min_max_dir`;
+---------+---------+
| EXPR$0 | EXPR$1 |
+---------+---------+
| 600 | 600 |
+---------+---------+
Here is the physical plan for count(dir0) query:
{code}
00-00 Screen : rowType = RecordType(BIGINT EXPR$0): rowcount = 20.0,
cumulative cost = {22.0 rows, 22.0 cpu, 0.0 io, 0.0 network, 0.0 memory}, id =
1346
00-01 Project(EXPR$0=[$0]) : rowType = RecordType(BIGINT EXPR$0): rowcount
= 20.0, cumulative cost = {20.0 rows, 20.0 cpu, 0.0 io, 0.0 network, 0.0
memory}, id = 1345
00-02 Project(EXPR$0=[$0]) : rowType = RecordType(BIGINT EXPR$0):
rowcount = 20.0, cumulative cost = {20.0 rows, 20.0 cpu, 0.0 io, 0.0 network,
0.0 memory}, id = 1344
00-03
Scan(groupscan=[org.apache.drill.exec.store.pojo.PojoRecordReader@3da85d3b[columns
= null, isStarQuery = false, isSkipQuery = false]]) : rowType =
RecordType(BIGINT count): rowcount = 20.0, cumulative cost = {20.0 rows, 20.0
cpu, 0.0 io, 0.0 network, 0.0 memory}, id = 1343
{code}
Here is part of the explain plan for the count(dir0) and count(dir1) in the
same select:
{code}
00-00 Screen : rowType = RecordType(BIGINT EXPR$0, BIGINT EXPR$1): rowcount
= 60.0, cumulative cost = {1206.0 rows, 15606.0 cpu, 0.0 io, 0.0 network, 0.0
memory}, id = 1623
00-01 Project(EXPR$0=[$0], EXPR$1=[$1]) : rowType = RecordType(BIGINT
EXPR$0, BIGINT EXPR$1): rowcount = 60.0, cumulative cost = {1200.0 rows,
15600.0 cpu, 0.0 io, 0.0 network, 0.0 memory}, id = 1622
00-02 StreamAgg(group=[{}], EXPR$0=[COUNT($0)], EXPR$1=[COUNT($1)]) :
rowType = RecordType(BIGINT EXPR$0, BIGINT EXPR$1): rowcount = 60.0, cumulative
cost = {1200.0 rows, 15600.0 cpu, 0.0 io, 0.0 network, 0.0 memory}, id = 1621
00-03 Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath
[path=maprfs:/drill/testdata/min_max_dir/1999/Apr/voter20.parquet/0_0_0.parquet],
ReadEntryWithPath
[path=maprfs:/drill/testdata/min_max_dir/1999/MAR/voter15.parquet/0_0_0.parquet],
ReadEntryWithPath
[path=maprfs:/drill/testdata/min_max_dir/1985/jan/voter5.parquet/0_0_0.parquet],
ReadEntryWithPath
[path=maprfs:/drill/testdata/min_max_dir/1985/apr/voter60.parquet/0_0_0.parquet],...,
ReadEntryWithPath
[path=maprfs:/drill/testdata/min_max_dir/2014/jul/voter35.parquet/0_0_0.parquet]],
selectionRoot=maprfs:/drill/testdata/min_max_dir, numFiles=16,
usedMetadataFile=false, columns=[`dir0`, `dir1`]]]) : rowType = RecordType(ANY
dir0, ANY dir1): rowcount = 600.0, cumulative cost = {600.0 rows, 1200.0 cpu,
0.0 io, 0.0 network, 0.0 memory}, id = 1620
{code}
Notice that in the first case,
"org.apache.drill.exec.store.pojo.PojoRecordReader" is used.
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