com.amazon.redshift.core

Interface ResultHandler

All Known Implementing Classes:

BatchResultHandler, RedshiftResultSet.CursorResultHandler, RedshiftStatementImpl.StatementResultHandler, ResultHandlerBase, ResultHandlerDelegate

public interface ResultHandler

Callback interface for passing query results from the protocol-specific layer to the protocol-independent JDBC implementation code.

In general, a single query execution will consist of a number of calls to handleResultRows, handleCommandStatus, handleWarning, and handleError, followed by a single call to handleCompletion when query execution is complete. If the caller wants to throw SQLException, this can be done in handleCompletion.

Each executed query ends with a call to handleResultRows, handleCommandStatus, or handleError. If an error occurs, subsequent queries won't generate callbacks.

Author:

Oliver Jowett (oliver@opencloud.com)

Method Summary

Modifier and Type	Method and Description
SQLException	getException() Returns the first encountered exception.
SQLWarning	getWarning() Returns the first encountered warning.
void	handleCommandStatus(String status, long updateCount, long insertOID) Called when a query that did not return a resultset completes.
void	handleCompletion() Called before a QueryExecutor method returns.
void	handleError(SQLException error) Called when an error occurs.
void	handleResultRows(Query fromQuery, Field[] fields, List<Tuple> tuples, ResultCursor cursor, RedshiftRowsBlockingQueue<Tuple> queueTuples, int[] rowCount, Thread ringBufferThread) Called when result rows are received from a query.
void	handleWarning(SQLWarning warning) Called when a warning is emitted.
void	secureProgress() Callback for batch statements.
void	setStatementStateIdleFromInQuery() Set statement state on completion of the Ring buffer thread.
void	setStatementStateInQueryFromIdle() Set statement state on start from IDLE to IN_QUERY, in case Ring Buffer thread reset the new query state as IDLE.
boolean	wantsScrollableResultSet() Check the statement type

Method Detail

handleResultRows

void handleResultRows(Query fromQuery,
                      Field[] fields,
                      List<Tuple> tuples,
                      ResultCursor cursor,
                      RedshiftRowsBlockingQueue<Tuple> queueTuples,
                      int[] rowCount,
                      Thread ringBufferThread)

Called when result rows are received from a query.

Parameters:

fromQuery - the underlying query that generated these results; this may not be very specific (e.g. it may be a query that includes multiple statements).

fields - column metadata for the resultset; might be null if Query.QUERY_NO_METADATA was specified.

tuples - the actual data. If this is set then queueTuples will be null.

cursor - a cursor to use to fetch additional data; null if no further results are present.

queueTuples - the actual data in a blocking queue. If this is set then tuples will be null.

rowCount - number of rows fetched from the socket.

ringBufferThread - a thread to fetch rows in the limited rows buffer.

handleCommandStatus

void handleCommandStatus(String status,
                         long updateCount,
                         long insertOID)

Called when a query that did not return a resultset completes.

Parameters:

status - the command status string (e.g. "SELECT") returned by the backend

updateCount - the number of rows affected by an INSERT, UPDATE, DELETE, FETCH, or MOVE command; -1 if not available.

insertOID - for a single-row INSERT query, the OID of the newly inserted row; 0 if not available.

handleWarning

void handleWarning(SQLWarning warning)

Called when a warning is emitted.

Parameters:

warning - the warning that occurred.

handleError

void handleError(SQLException error)

Called when an error occurs. Subsequent queries are abandoned; in general the only calls between a handleError call and a subsequent handleCompletion call are handleError or handleWarning.

Parameters:

error - the error that occurred

handleCompletion

void handleCompletion()
               throws SQLException

Called before a QueryExecutor method returns. This method may throw a SQLException if desired; if it does, the QueryExecutor method will propagate that exception to the original caller.

Throws:

SQLException - if the handler wishes the original method to throw an exception.

secureProgress

void secureProgress()

Callback for batch statements. In case batch statement is executed in autocommit==true mode, the executor might commit "as it this it is best", so the result handler should track which statements are executed successfully and which are not.

getException

SQLException getException()

Returns the first encountered exception. The rest are chained via SQLException.setNextException(SQLException)

Returns:

the first encountered exception

getWarning

SQLWarning getWarning()

Returns the first encountered warning. The rest are chained via SQLException.setNextException(SQLException)

Returns:

the first encountered warning

setStatementStateIdleFromInQuery

void setStatementStateIdleFromInQuery()

Set statement state on completion of the Ring buffer thread.

setStatementStateInQueryFromIdle

void setStatementStateInQueryFromIdle()

Set statement state on start from IDLE to IN_QUERY, in case Ring Buffer thread reset the new query state as IDLE.

wantsScrollableResultSet

boolean wantsScrollableResultSet()

Check the statement type

Returns:

true if scrollable, false for forward only.