com.datastax.driver.core

Interface ContinuousPagingSession

All Superinterfaces:

AutoCloseable, Closeable, Session

All Known Implementing Classes:

AbstractSession

public interface ContinuousPagingSession
extends Session

A session that has the ability to execute continuous paging queries.

This interface exists solely for backward compatibility purposes, because adding the methods directly to Session would have broken clients that implemented it. In practice, any session returned by the driver is also a continuous paging session, and can be safely casted.

This will be merged in the parent interface in the next major version.

Nested Class Summary

Nested classes/interfaces inherited from interface com.datastax.driver.core.Session

Session.State

Method Summary

Modifier and Type	Method and Description
ContinuousPagingResult	executeContinuously(Statement statement, ContinuousPagingOptions options) Convenience method to execute a continuous query in a synchronous context.
ListenableFuture<AsyncContinuousPagingResult>	executeContinuouslyAsync(Statement statement, ContinuousPagingOptions options) Executes the provided query with continuous paging.

Methods inherited from interface com.datastax.driver.core.Session

close, closeAsync, execute, execute, execute, execute, executeAsync, executeAsync, executeAsync, executeAsync, getCluster, getLoggedKeyspace, getState, init, initAsync, isClosed, prepare, prepare, prepareAsync, prepareAsync

Method Detail

executeContinuouslyAsync

ListenableFuture<AsyncContinuousPagingResult> executeContinuouslyAsync(Statement statement,
                                                                       ContinuousPagingOptions options)

Executes the provided query with continuous paging.

The server will push all requested pages asynchronously, according to the options passed in as a parameter. The client should consume all pages as quickly as possible, to avoid blocking the server for too long. The server will adjust the rate according to the client speed, but it will give up if the client does not consume any pages in a period of time equal to the read request timeout.

This functionality is typically used by tools that want to retrieve the entire data set as quickly as possible, typically for analytics queries. Such tools should also make sure to contact a replica directly, by setting a routing key or token in the statement, so that the server can further optimize ConsistencyLevel.ONE queries by reading data from local disk and keeping iterators open across pages. This optimization is only available if the coordinator is a replica and the consistency level is ONE. If this is not the case, the coordinator will retrieve pages one by one from replicas. Note that when the optimization kicks in (range query at ONE performed directly on a replica), the snitch is bypassed and the coordinator will always chose itself as a replica. Therefore, other functionality such as probabilistic read repair and speculative retry is also not available when contacting a replica at ONE.

Parameters:

statement - the CQL query to execute (that can be any Statement).

options - the query options (this can't be null).

Returns:

a future to the first asynchronous result.

executeContinuously

ContinuousPagingResult executeContinuously(Statement statement,
                                           ContinuousPagingOptions options)

Convenience method to execute a continuous query in a synchronous context.

This method calls executeContinuouslyAsync(Statement, ContinuousPagingOptions) internally, and takes care of chaining the successive results into a convenient iterable, provided that you always access the result from the same thread.

Parameters:

statement - the CQL query to execute (that can be any Statement).

options - the query options (this can't be null).

Returns:

a synchronous iterable on the results.