com.lancedb.lance.file

Class LanceFileReader

java.lang.Object

com.lancedb.lance.file.LanceFileReader

All Implemented Interfaces:

AutoCloseable

public class LanceFileReader
extends Object
implements AutoCloseable

Method Summary

Modifier and Type	Method and Description
void	close() Close the LanceFileReader
long	numRows() Get the number of rows in the Lance file
static LanceFileReader	open(String path, org.apache.arrow.memory.BufferAllocator allocator) Open a LanceFileReader from a file URI
static LanceFileReader	open(String path, Map<String,String> storageOptions, org.apache.arrow.memory.BufferAllocator allocator) Open a LanceFileReader from a file URI
org.apache.arrow.vector.ipc.ArrowReader	readAll(List<String> projectedNames, List<Range> ranges, int batchSize) Read all rows from the Lance file
org.apache.arrow.vector.types.pojo.Schema	schema() Get the schema of the Lance file

Methods inherited from class java.lang.Object

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

Method Detail

open

public static LanceFileReader open(String path,
                                   org.apache.arrow.memory.BufferAllocator allocator)
                            throws IOException

Open a LanceFileReader from a file URI

Parameters:

path - the URI to the Lance file

allocator - the Arrow BufferAllocator to use for the reader

Returns:

a new LanceFileReader

Throws:

IOException

open

public static LanceFileReader open(String path,
                                   Map<String,String> storageOptions,
                                   org.apache.arrow.memory.BufferAllocator allocator)
                            throws IOException

Open a LanceFileReader from a file URI

Parameters:

path - the URI to the Lance file

storageOptions - optional storage options for the Lance file

allocator - the Arrow BufferAllocator to use for the reader

Returns:

a new LanceFileReader

Throws:

IOException

close

public void close()
           throws Exception

Close the LanceFileReader

This method must be called to release resources when the reader is no longer needed.

Specified by:

close in interface AutoCloseable

Throws:

Exception

numRows

public long numRows()
             throws IOException

Get the number of rows in the Lance file

Returns:

the number of rows in the Lance file

Throws:

IOException

schema

public org.apache.arrow.vector.types.pojo.Schema schema()

Get the schema of the Lance file

Returns:

the schema of the Lance file

readAll

public org.apache.arrow.vector.ipc.ArrowReader readAll(@Nullable
                                                       List<String> projectedNames,
                                                       @Nullable
                                                       List<Range> ranges,
                                                       int batchSize)
                                                throws IOException

Read all rows from the Lance file

Parameters:

batchSize - the maximum number of rows to read in a single batch

projectedNames - optional list of column names to project; if null, all columns are read

ranges - optional array of ranges to read; if null, all rows are read.

Returns:

an ArrowReader for the Lance file

Throws:

IOException