com.datastax.oss.driver.api.core.cql

Interface PagingState

public interface PagingState

A safe wrapper around the paging state of a query.

This class performs additional checks to fail fast if the paging state is not reused on the same query, and it provides utility methods for conversion to/from strings and byte arrays.

The serialized form returned by toBytes() and Object.toString() is an opaque sequence of bytes. Note however that it is not cryptographically secure: the contents are not encrypted and the checks are performed with a simple MD5 checksum. If you need stronger guarantees, you should build your own wrapper around ExecutionInfo.getPagingState().

Method Summary

Modifier and Type	Method and Description
static PagingState	fromBytes(byte[] bytes) Parses an instance from a byte array previously generated with toBytes().
static PagingState	fromString(String string) Parses an instance from a string previously generated with toString().
ByteBuffer	getRawPagingState() Returns the underlying "unsafe" paging state (the equivalent of ExecutionInfo.getPagingState()).
default boolean	matches(Statement<?> statement) Checks if this paging state can be safely reused for the given statement.
boolean	matches(Statement<?> statement, Session session) Alternative to matches(Statement) that specifies the session the statement will be executed with.
byte[]	toBytes() Returns a representation of this object as a byte array.

Method Detail

fromString

@NonNull
static PagingState fromString(@NonNull
                                       String string)

Parses an instance from a string previously generated with toString().

fromBytes

@NonNull
static PagingState fromBytes(byte[] bytes)

Parses an instance from a byte array previously generated with toBytes().

toBytes

byte[] toBytes()

Returns a representation of this object as a byte array.

matches

default boolean matches(@NonNull
                        Statement<?> statement)

Checks if this paging state can be safely reused for the given statement. Specifically, the query string and any bound values must match.

Note that, if statement is a SimpleStatement with bound values, those values must be encoded in order to perform the check. This method uses the default codec registry and default protocol version. This might fail if you use custom codecs; in that case, use matches(Statement, Session) instead.

If statement is a BoundStatement, it is always safe to call this method.

matches

boolean matches(@NonNull
                Statement<?> statement,
                @Nullable
                Session session)

Alternative to matches(Statement) that specifies the session the statement will be executed with. You only need this for simple statements, and if you use custom codecs. Bound statements already know which session they are attached to.

getRawPagingState

@NonNull
ByteBuffer getRawPagingState()

Returns the underlying "unsafe" paging state (the equivalent of ExecutionInfo.getPagingState()).