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  1. Apache Drill
  2. DRILL-4735

Count(dir0) on parquet returns 0 result

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      Description

      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:

      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
      

      Here is part of the explain plan for the count(dir0) and count(dir1) in the same select:

      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
      

      Notice that in the first case, "org.apache.drill.exec.store.pojo.PojoRecordReader" is used.

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              • Assignee:
                arina Arina Ielchiieva
                Reporter:
                knguyen Krystal
                Reviewer:
                Jinfeng Ni
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                  Updated:
                  Resolved: