org.apache.druid.frame.write

Class FrameWriterUtils

java.lang.Object

org.apache.druid.frame.write.FrameWriterUtils

public class FrameWriterUtils
extends Object

Utility methods used by FrameWriter implementations.

Field Summary

Fields

Modifier and Type	Field and Description
static byte	NULL_STRING_MARKER
static byte[]	NULL_STRING_MARKER_ARRAY
static String	RESERVED_FIELD_PREFIX

Constructor Summary

Constructors

Constructor and Description
FrameWriterUtils()

Method Summary

Modifier and Type	Method and Description
static void	copyByteBufferToMemory(ByteBuffer src, org.apache.datasketches.memory.WritableMemory dst, long dstPosition, int len, boolean allowNullBytes) Copies "len" bytes from src.position() to "dstPosition" in "memory".
static Set<String>	findDisallowedFieldNames(RowSignature signature) Checks the provided signature for any disallowed field names.
static List<ByteBuffer>	getUtf8ByteBuffersFromStringArraySelector(ColumnValueSelector selector) Retrieves UTF-8 byte buffers from a ColumnValueSelector, which is expected to be the kind of selector you get for an ARRAY<STRING> column.
static List<ByteBuffer>	getUtf8ByteBuffersFromStringSelector(DimensionSelector selector, boolean multiValue) Retrieves UTF-8 byte buffers from a DimensionSelector, which is expected to be the kind of selector you get for an STRING column.
static RowSignature	replaceUnknownTypesWithNestedColumns(RowSignature rowSignature)
static void	verifySortColumns(List<KeyColumn> keyColumns, RowSignature signature) Verifies whether the provided sortColumns are all sortable, and are a prefix of the signature.
static long	writeFrameHeader(org.apache.datasketches.memory.WritableMemory memory, long startPosition, FrameType frameType, long totalSize, int numRows, int numRegions, boolean permuted) Writes a frame header to a memory locations.

Methods inherited from class java.lang.Object

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

Field Detail

NULL_STRING_MARKER

public static final byte NULL_STRING_MARKER

See Also:

Constant Field Values

NULL_STRING_MARKER_ARRAY

public static final byte[] NULL_STRING_MARKER_ARRAY

RESERVED_FIELD_PREFIX

public static final String RESERVED_FIELD_PREFIX

See Also:

Constant Field Values

Constructor Detail

FrameWriterUtils

public FrameWriterUtils()

Method Detail

writeFrameHeader

public static long writeFrameHeader(org.apache.datasketches.memory.WritableMemory memory,
                                    long startPosition,
                                    FrameType frameType,
                                    long totalSize,
                                    int numRows,
                                    int numRegions,
                                    boolean permuted)

Writes a frame header to a memory locations.

getUtf8ByteBuffersFromStringSelector

public static List<ByteBuffer> getUtf8ByteBuffersFromStringSelector(DimensionSelector selector,
                                                                    boolean multiValue)

Retrieves UTF-8 byte buffers from a DimensionSelector, which is expected to be the kind of selector you get for an STRING column. Null strings are returned as NULL_STRING_MARKER_ARRAY.

Parameters:

selector - the selector

multiValue - if true, return an array that corresponds exactly to DimensionSelector.getRow(). if false, always return a single-valued array. In particular, this means [] is returned as [NULL_STRING_MARKER_ARRAY].

getUtf8ByteBuffersFromStringArraySelector

public static List<ByteBuffer> getUtf8ByteBuffersFromStringArraySelector(ColumnValueSelector selector)

Retrieves UTF-8 byte buffers from a ColumnValueSelector, which is expected to be the kind of selector you get for an ARRAY<STRING> column. Null strings are returned as NULL_STRING_MARKER_ARRAY.

findDisallowedFieldNames

public static Set<String> findDisallowedFieldNames(RowSignature signature)

Checks the provided signature for any disallowed field names. Returns any that are found.

verifySortColumns

public static void verifySortColumns(List<KeyColumn> keyColumns,
                                     RowSignature signature)

Verifies whether the provided sortColumns are all sortable, and are a prefix of the signature. This is required because it allows us to treat the sort key as a chunk of bytes. Exits quietly if the sort columns are OK. Throws an exception if there is a problem.

Throws:

IllegalArgumentException - if there is a problem

copyByteBufferToMemory

public static void copyByteBufferToMemory(ByteBuffer src,
                                          org.apache.datasketches.memory.WritableMemory dst,
                                          long dstPosition,
                                          int len,
                                          boolean allowNullBytes)

Copies "len" bytes from src.position() to "dstPosition" in "memory". Does not update the position of src.

Throws:

InvalidNullByteException - if "allowNullBytes" is false and a null byte is encountered

replaceUnknownTypesWithNestedColumns

public static RowSignature replaceUnknownTypesWithNestedColumns(RowSignature rowSignature)