[PARQUET-2026] Allow empty row in parquet file

• Type: Task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.12.0
• Fix Version/s: 1.14.0
• Component/s: parquet-mr
• Labels: Drill empty-file
• Assignee: Unassigned
• Reporter: Vitalii Diravka
• Created: 13/Apr/21 06:10
• Updated: 12/Apr/23 01:48

Description

PARQUET-1851 starts abandon to write parquet files with schema (meta information), but with 0 rows, aka empty files.
In result it prevent to store empty tables in DRILL by using parquet files, for example:

CREATE TABLE dfs.tmp.%s AS SELECT * FROM cp.`employee.json` WHERE 1=0

CREATE TABLE dfs.tmp.%s AS select * from dfs.`parquet/alltypes_required.parquet` where `col_int` = 0

create table dfs.tmp.%s as select * from dfs.`parquet/empty/complex/empty_complex.parquet`

So PARQUET-1851 breaks the following test cases:

TestUntypedNull.testParquetTableCreation   TestParquetWriterEmptyFiles.testComplexEmptyFileSchema   TestParquetWriterEmptyFiles.testWriteEmptyFile   TestParquetWriterEmptyFiles.testWriteEmptyFileWithSchema   TestParquetWriterEmptyFiles.testWriteEmptySchemaChange TestMetastoreCommands.testAnalyzeEmptyRequiredParquetTable  TestMetastoreCommands.testSelectEmptyRequiredParquetTable

 I suggest to use warning in the process of creating empty parquet files or create alternative endBlock for backward compatibility with other tools:

Issue Links

• is broken by: PARQUET-1851 ParquetMetadataConveter throws NPE in an Iceberg unit test
• Is contained by: DRILL-7825 Error: SYSTEM ERROR: RuntimeException: Unknown logical type <LogicalType UUID:UUIDType()>
• Is contained by: DRILL-7907 Replace ParquetFileWriter in Drill with parquet version
• is required by: DRILL-7825 Error: SYSTEM ERROR: RuntimeException: Unknown logical type <LogicalType UUID:UUIDType()>