uk.ac.starlink.parquet

Class InputColumns

java.lang.Object

uk.ac.starlink.parquet.InputColumns

public class InputColumns
extends java.lang.Object

Provides InputColumn instances that know how to read parquet column data.

Since:

24 Feb 2021

Field Summary

Fields

Modifier and Type	Field and Description
static byte	BAD_BYTE
static int	BAD_INT
static long	BAD_LONG
static short	BAD_SHORT

Method Summary

Modifier and Type	Method and Description
static InputColumn<?>	createInputColumn(MessageType schema, java.lang.String[] path) Returns an InputColumn for reading a given column from a parquet file.
static InputColumn<java.lang.String>	createUnsupportedColumn(ColumnDescriptor cdesc) Returns an InputColumn instance that is unable to read any data from the parquet file, presumably because of an unsupported data type.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BAD_BYTE

public static final byte BAD_BYTE

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Constant Field Values

BAD_SHORT

public static final short BAD_SHORT

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Constant Field Values

BAD_INT

public static final int BAD_INT

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Constant Field Values

BAD_LONG

public static final long BAD_LONG

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Constant Field Values

Method Detail

createInputColumn

public static InputColumn<?> createInputColumn(MessageType schema,
                                               java.lang.String[] path)

Returns an InputColumn for reading a given column from a parquet file.

Parameters:

schema - table schema

path - table column identifier

Returns:

input column reader, or null if the column type is not supported

createUnsupportedColumn

public static InputColumn<java.lang.String> createUnsupportedColumn(ColumnDescriptor cdesc)

Returns an InputColumn instance that is unable to read any data from the parquet file, presumably because of an unsupported data type. The column has a type of String, but always returns null values.

Parameters:

cdesc - parquet column descriptor

Returns:

dummy column