Package com.databricks.jdbc.api.impl.thrift

Class StreamingColumnarResult

java.lang.Object

com.databricks.jdbc.api.impl.thrift.StreamingColumnarResult

All Implemented Interfaces:

IExecutionResult

public class StreamingColumnarResult
extends Object
implements IExecutionResult

High-throughput streaming implementation for Thrift columnar results.

Uses ThriftStreamingProvider for proactive batch prefetching, achieving throughput comparable to eager loading while maintaining the memory benefits of lazy loading.

Key features:

• Background prefetch thread fetches batches ahead of consumption
• Sliding window limits memory usage to a configurable number of batches
• Non-blocking iteration when prefetch keeps up with consumption
• Maintains correct row ordering through sequential fetch
• Type-safe: Uses generic ThriftStreamingProvider<ColumnarRowView>

This implementation replaces LazyThriftResult for improved throughput while maintaining the same IExecutionResult interface.

Constructor Summary

Constructors

Constructor	Description
StreamingColumnarResult(TFetchResultsResp initialResponse, IDatabricksStatementInternal statement, IDatabricksSession session)	Creates a new StreamingColumnarResult.

Method Summary

Modifier and Type	Method	Description
void	close()	Closes this result and releases associated resources.
int	getBatchesInMemory()	Gets the number of batches currently in memory.
long	getChunkCount()	Gets the chunk count.
long	getCurrentRow()	Gets the current row index (0-based).
Object	getObject(int columnIndex)	Gets the value at the specified column index for the current row.
long	getRowCount()	Gets the number of rows in the current batch.
long	getTotalRowsFetched()	Gets the total number of rows fetched from the server so far.
boolean	hasNext()	Checks if there are more rows available without advancing the cursor.
boolean	isCompletelyFetched()	Checks if all data has been fetched from the server.
boolean	next()	Moves the cursor to the next row.

Methods inherited from class java.lang.Object

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

Constructor Detail

StreamingColumnarResult

public StreamingColumnarResult(TFetchResultsResp initialResponse,
                               IDatabricksStatementInternal statement,
                               IDatabricksSession session)
                        throws DatabricksSQLException

Creates a new StreamingColumnarResult.

Configuration values (maxBatchesInMemory, timeout) are read from the session's connection context.

Parameters:

initialResponse - The initial Thrift response containing the first batch

statement - The statement that generated this result

session - The session for fetching additional batches

Throws:

DatabricksSQLException - if initialization fails

Method Detail

getObject

public Object getObject(int columnIndex)
                 throws DatabricksSQLException

Gets the value at the specified column index for the current row.

Specified by:

getObject in interface IExecutionResult

Parameters:

columnIndex - the zero-based column index

Returns:

the value at the specified column

Throws:

DatabricksSQLException - if access fails

getCurrentRow

public long getCurrentRow()

Gets the current row index (0-based). Returns -1 if before the first row.

Specified by:

getCurrentRow in interface IExecutionResult

Returns:

the current row index

next

public boolean next()
             throws DatabricksSQLException

Moves the cursor to the next row. Fetches additional batches from server if needed.

Specified by:

next in interface IExecutionResult

Returns:

true if there is a next row, false if at the end

Throws:

DatabricksSQLException - if an error occurs

hasNext

public boolean hasNext()

Checks if there are more rows available without advancing the cursor.

Specified by:

hasNext in interface IExecutionResult

Returns:

true if there are more rows, false otherwise

close

public void close()

Closes this result and releases associated resources.

Specified by:

close in interface IExecutionResult

getRowCount

public long getRowCount()

Gets the number of rows in the current batch.

Specified by:

getRowCount in interface IExecutionResult

Returns:

the number of rows in the current batch

getChunkCount

public long getChunkCount()

Gets the chunk count. Always returns 0 for thrift columnar results (chunks are an Arrow concept).

Specified by:

getChunkCount in interface IExecutionResult

Returns:

0

getTotalRowsFetched

public long getTotalRowsFetched()

Gets the total number of rows fetched from the server so far.

Returns:

the total rows fetched

isCompletelyFetched

public boolean isCompletelyFetched()

Checks if all data has been fetched from the server.

Returns:

true if end of stream reached

getBatchesInMemory

public int getBatchesInMemory()

Gets the number of batches currently in memory.

Returns:

the batch count in memory