Incubation

ParquetWriter writes data into Parquet files.

The component supports file compression, writing to local files, remote files and writing to output port.

The output port writing supports both discrete and stream write modes.

ParquetWriter does not propagate metadata.

The component has no metadata template.

The component auto-generates a Parquet schema from the metadata on input port.

The Parquet format attributes Row group size and Page size influence how the data is organized inside the output Parquet file. These attributes can be fine-tuned to optimize output file size or write performance, more details can be found in the Apache Parquet documentation.

The component holds up to Row group size in heap memory at once.

The component always overwrites existing target files. Appending to an existing file is not supported.

Parquet Schema

The component attribute Parquet schema can be used for customization of CloverDX to Parquet data type conversion. The customization is done in a Parquet schema mapping dialog, shown in Figure 65.1, Parquet file schema dialog.

In this dialog, you can see all the metadata fields, their types and a target Parquet type. This is an abstraction above Parquet primitive and logical types (as described in Apache Parquet documentation). The mapping of Parquet types to primitive and logical types is described in table Parquet Types. The Parquet type selection offers only those types compatible with the specific CloverDX field data type.

Figure 65.1. Parquet file schema dialog

The implicit auto-mapped types are shown in grey italic font, in contrast to manually mapped types, shown in black. If the metadata contains a field with an unsupported data type (e.g. a map), it is shown as Unsupported also in the mapping dialog and the Parquet type selection is disabled.

The Parquet schema is stored as a JSON in the job XML. This allows for better readability of the mapping and tracking of changes.

Table 65.6. Parquet Types

Parquet Type	Primitive Type	Logical Type	Properties
String	BYTE_ARRAY	STRING
Enum	BYTE_ARRAY	ENUM
Integer	INT32 (width <= 32) INT64 (width == 64)	INT(width, signed)	width (8/16/32/64)
Decimal	INT32 (1 <= precision <= 9) INT64 (10 <= precision <= 18) BYTE_ARRAY (19 <= precision)	DECIMAL	precision (>=0) scale (>=0)
Date	INT32	DATE
Time	INT32 (precision == millis) INT64 (precision == micros/nanos)	TIME	precision (millis/micros/nanos) utcAdjustment (true/false)
Timestamp	INT64	TIMESTAMP	precision (millis/micros/nanos) utcAdjustment (true/false)
Interval	FIXED_LEN_BYTE_ARRAY	INTERVAL
BSON	BYTE_ARRAY	BSON
JSON	BYTE_ARRAY	JSON
Double	DOUBLE
Boolean	BOOLEAN
Binary	BYTE_ARRAY

Writing of nested types (lists and maps) are not supported.

The unsigned INT types and the INT96 primitive type are not supported.

The UUID logical type is not supported.

Partitioning (by value, or by record count) is not supported.