StatementWrapper (DataStax Java Driver for Apache Cassandra

java.lang.Object
- com.datastax.driver.core.Statement
- - com.datastax.driver.core.StatementWrapper

public abstract class StatementWrapper
extends Statement

Base class for custom Statement implementations that wrap another statement.

This is intended for use with a custom RetryPolicy, LoadBalancingPolicy or SpeculativeExecutionPolicy. The client code can wrap a statement to "mark" it, or add information that will lead to special handling in the policy.

Example:


 // Define your own subclass
 public class MyCustomStatement extends StatementWrapper {
     public MyCustomStatement(Statement wrapped) {
         super(wrapped);
     }
 }

 // In your load balancing policy, add a special case for that new type
 public class MyLoadBalancingPolicy implements LoadBalancingPolicy {
     public Iterator<Host> newQueryPlan(String loggedKeyspace, Statement statement) {
         if (statement instanceof MyCustomStatement) {
             // return specially crafted plan
         } else {
             // return default plan
         }
     }
 }

 // The client wraps whenever it wants to trigger the special plan
 Statement s = new SimpleStatement("...");
 session.execute(s);                         // will use default plan
 session.execute(new MyCustomStatement(s));  // will use special plan

Field Summary
- Fields inherited from class com.datastax.driver.core.Statement
  idempotent, NULL_PAYLOAD_VALUE

Constructor Summary

Constructors
Modifier Constructor and Description

protected StatementWrapper(Statement wrapped)
Builds a new instance.

Constructors
Modifier	Constructor and Description
`protected`	`StatementWrapper(Statement wrapped)` Builds a new instance.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`Statement`	`disableTracing()` Disables tracing for this query.
`Statement`	`enableTracing()` Enables tracing for this query.
`ConsistencyLevel`	`getConsistencyLevel()` The consistency level for this query.
`long`	`getDefaultTimestamp()` The default timestamp for this query.
`int`	`getFetchSize()` The fetch size for this query.
`Host`	`getHost()`
`String`	`getKeyspace()` Returns the keyspace this query operates on.
`Map<String,ByteBuffer>`	`getOutgoingPayload()` Returns this statement's outgoing payload.
`ByteBuffer`	`getPagingState()`
`int`	`getReadTimeoutMillis()` Return the per-host read timeout that was set for this statement.
`RetryPolicy`	`getRetryPolicy()` Returns the retry policy sets for this query, if any.
`ByteBuffer`	`getRoutingKey(ProtocolVersion protocolVersion, CodecRegistry codecRegistry)` Returns the routing key (in binary raw form) to use for token aware routing of this query.
`ConsistencyLevel`	`getSerialConsistencyLevel()` The serial consistency level for this query.
`Boolean`	`isIdempotent()` Whether this statement is idempotent, i.e.
`boolean`	`isIdempotentWithDefault(QueryOptions queryOptions)`
`boolean`	`isTracing()` Returns whether tracing is enabled for this query or not.
`int`	`requestSizeInBytes(ProtocolVersion protocolVersion, CodecRegistry codecRegistry)` Returns the number of bytes required to encode this statement.
`Statement`	`setConsistencyLevel(ConsistencyLevel consistency)` Sets the consistency level for the query.
`Statement`	`setDefaultTimestamp(long defaultTimestamp)` Sets the default timestamp for this query (in microseconds since the epoch).
`Statement`	`setFetchSize(int fetchSize)` Sets the query fetch size.
`Statement`	`setHost(Host host)` Sets the `Host` that should handle this query.
`Statement`	`setIdempotent(boolean idempotent)` Sets whether this statement is idempotent.
`Statement`	`setOutgoingPayload(Map<String,ByteBuffer> payload)` Set the given outgoing payload on this statement.
`Statement`	`setPagingState(PagingState pagingState)` Sets the paging state.
`Statement`	`setPagingState(PagingState pagingState, CodecRegistry codecRegistry)` Sets the paging state.
`Statement`	`setPagingStateUnsafe(byte[] pagingState)` Sets the paging state.
`Statement`	`setReadTimeoutMillis(int readTimeoutMillis)` Overrides the default per-host read timeout (`SocketOptions.getReadTimeoutMillis()`) for this statement.
`Statement`	`setRetryPolicy(RetryPolicy policy)` Sets the retry policy to use for this query.
`Statement`	`setSerialConsistencyLevel(ConsistencyLevel serialConsistency)` Sets the serial consistency level for the query.

Methods inherited from class com.datastax.driver.core.Statement
isBatchIdempotent

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - StatementWrapper
```
protected StatementWrapper(Statement wrapped)
```
    Builds a new instance.
    
    Parameters:
    
    wrapped - the wrapped statement.
- Method Detail
  - setConsistencyLevel
```
public Statement setConsistencyLevel(ConsistencyLevel consistency)
```
    Description copied from class: Statement
    
    Sets the consistency level for the query.
    
    Overrides:
    
    setConsistencyLevel in class Statement
    
    Parameters:
    
    consistency - the consistency level to set.
    
    Returns:
    
    this Statement object.
  - getConsistencyLevel
```
public ConsistencyLevel getConsistencyLevel()
```
    Description copied from class: Statement
    
    The consistency level for this query.
    
    Overrides:
    
    getConsistencyLevel in class Statement
    
    Returns:
    
    the consistency level for this query, or null if no consistency level has been specified (through setConsistencyLevel). In the latter case, the default consistency level will be used.
  - setSerialConsistencyLevel
```
public Statement setSerialConsistencyLevel(ConsistencyLevel serialConsistency)
```
    Description copied from class: Statement
    
    Sets the serial consistency level for the query.
    The serial consistency level is only used by conditional updates (INSERT, UPDATE or DELETE statements with an IF condition). For those, the serial consistency level defines the consistency level of the serial phase (or "paxos" phase) while the normal consistency level defines the consistency for the "learn" phase, i.e. what type of reads will be guaranteed to see the update right away. For instance, if a conditional write has a regular consistency of QUORUM (and is successful), then a QUORUM read is guaranteed to see that write. But if the regular consistency of that write is ANY, then only a read with a consistency of SERIAL is guaranteed to see it (even a read with consistency ALL is not guaranteed to be enough).
    The serial consistency can only be one of ConsistencyLevel.SERIAL or ConsistencyLevel.LOCAL_SERIAL. While ConsistencyLevel.SERIAL guarantees full linearizability (with other SERIAL updates), ConsistencyLevel.LOCAL_SERIAL only guarantees it in the local data center.
    The serial consistency level is ignored for any query that is not a conditional update (serial reads should use the regular consistency level for instance).
    
    Overrides:
    
    setSerialConsistencyLevel in class Statement
    
    Parameters:
    
    serialConsistency - the serial consistency level to set.
    
    Returns:
    
    this Statement object.
  - getSerialConsistencyLevel
```
public ConsistencyLevel getSerialConsistencyLevel()
```
    Description copied from class: Statement
    
    The serial consistency level for this query.
    See Statement.setSerialConsistencyLevel(ConsistencyLevel) for more detail on the serial consistency level.
    
    Overrides:
    
    getSerialConsistencyLevel in class Statement
    
    Returns:
    
    the serial consistency level for this query, or null if no serial consistency level has been specified (through Statement.setSerialConsistencyLevel(ConsistencyLevel)). In the latter case, the default serial consistency level will be used.
  - enableTracing
```
public Statement enableTracing()
```
    Description copied from class: Statement
    
    Enables tracing for this query.
    By default (that is unless you call this method), tracing is not enabled.
    
    Overrides:
    
    enableTracing in class Statement
    
    Returns:
    
    this Statement object.
  - disableTracing
```
public Statement disableTracing()
```
    Description copied from class: Statement
    
    Disables tracing for this query.
    
    Overrides:
    
    disableTracing in class Statement
    
    Returns:
    
    this Statement object.
  - isTracing
```
public boolean isTracing()
```
    Description copied from class: Statement
    
    Returns whether tracing is enabled for this query or not.
    
    Overrides:
    
    isTracing in class Statement
    
    Returns:
    
    true if this query has tracing enabled, false otherwise.
  - getRoutingKey
```
public ByteBuffer getRoutingKey(ProtocolVersion protocolVersion,
                                CodecRegistry codecRegistry)
```
    Description copied from class: Statement
    
    Returns the routing key (in binary raw form) to use for token aware routing of this query.
    The routing key is optional in that implementers are free to return null. The routing key is an hint used for token-aware routing (see TokenAwarePolicy), and if provided should correspond to the binary value for the query partition key. However, not providing a routing key never causes a query to fail and if the load balancing policy used is not token aware, then the routing key can be safely ignored.
    
    Specified by:
    
    getRoutingKey in class Statement
    
    Parameters:
    
    protocolVersion - the protocol version that will be used if the actual implementation needs to serialize something to compute the key.
    
    codecRegistry - the codec registry that will be used if the actual implementation needs to serialize something to compute this key.
    
    Returns:
    
    the routing key for this query or null.
  - getKeyspace
```
public String getKeyspace()
```
    Description copied from class: Statement
    
    Returns the keyspace this query operates on.
    Note that not all query specify on which keyspace they operate on, and so this method can always return null. Firstly, some queries do not operate inside a keyspace: keyspace creation, USE queries, user creation, etc. Secondly, even query that operate within a keyspace do not have to specify said keyspace directly, in which case the currently logged in keyspace (the one set through a USE query (or through the use of Cluster.connect(String))). Lastly, as for the routing key, this keyspace information is only a hint for token-aware routing (since replica placement depend on the replication strategy in use which is a per-keyspace property) and having this method return null (or even a bogus keyspace name) will never cause the query to fail.
    
    Specified by:
    
    getKeyspace in class Statement
    
    Returns:
    
    the keyspace this query operate on if relevant or null.
  - setRetryPolicy
```
public Statement setRetryPolicy(RetryPolicy policy)
```
    Description copied from class: Statement
    
    Sets the retry policy to use for this query.
    The default retry policy, if this method is not called, is the one returned by Policies.getRetryPolicy() in the cluster configuration. This method is thus only useful in case you want to punctually override the default policy for this request.
    
    Overrides:
    
    setRetryPolicy in class Statement
    
    Parameters:
    
    policy - the retry policy to use for this query.
    
    Returns:
    
    this Statement object.
  - getRetryPolicy
```
public RetryPolicy getRetryPolicy()
```
    Description copied from class: Statement
    
    Returns the retry policy sets for this query, if any.
    
    Overrides:
    
    getRetryPolicy in class Statement
    
    Returns:
    
    the retry policy sets specifically for this query or null if no query specific retry policy has been set through Statement.setRetryPolicy(com.datastax.driver.core.policies.RetryPolicy) (in which case the Cluster retry policy will apply if necessary).
  - setFetchSize
```
public Statement setFetchSize(int fetchSize)
```
    Description copied from class: Statement
    
    Sets the query fetch size.
    The fetch size controls how much resulting rows will be retrieved simultaneously (the goal being to avoid loading too much results in memory for queries yielding large results). Please note that while value as low as 1 can be used, it is *highly* discouraged to use such a low value in practice as it will yield very poor performance. If in doubt, leaving the default is probably a good idea.
    Only SELECT queries only ever make use of this setting.
    Note that unlike other configuration, when this statement is prepared BoundStatements created off of PreparedStatement do not inherit this configuration.
    Note: Paging is not supported with the native protocol version 1. If you call this method with fetchSize > 0 and fetchSize != Integer.MAX_VALUE and the protocol version is in use (i.e. if you've force version 1 through Cluster.Builder.withProtocolVersion(com.datastax.driver.core.ProtocolVersion) or you use Cassandra 1.2), you will get UnsupportedProtocolVersionException when submitting this statement for execution.
    
    Overrides:
    
    setFetchSize in class Statement
    
    Parameters:
    
    fetchSize - the fetch size to use. If fetchSize &lte; 0, the default fetch size will be used. To disable paging of the result set, use fetchSize == Integer.MAX_VALUE.
    
    Returns:
    
    this Statement object.
  - getFetchSize
```
public int getFetchSize()
```
    Description copied from class: Statement
    
    The fetch size for this query.
    
    Overrides:
    
    getFetchSize in class Statement
    
    Returns:
    
    the fetch size for this query. If that value is less or equal to 0 (the default unless Statement.setFetchSize(int) is used), the default fetch size will be used.
  - setDefaultTimestamp
```
public Statement setDefaultTimestamp(long defaultTimestamp)
```
    Description copied from class: Statement
    Sets the default timestamp for this query (in microseconds since the epoch).
    This feature is only available when version V3 or higher of the native protocol is in use. With earlier versions, calling this method has no effect.
    The actual timestamp that will be used for this query is, in order of preference:
    - the timestamp specified directly in the CQL query string (using the USING TIMESTAMP syntax);
    - the timestamp specified through this method, if different from Long.MIN_VALUE;
    - the timestamp returned by the TimestampGenerator currently in use, if different from Long.MIN_VALUE.
    If none of these apply, no timestamp will be sent with the query and Cassandra will generate a server-side one (similar to the pre-V3 behavior).
    Note that unlike other configuration, when this statement is prepared BoundStatements created off of PreparedStatement do not inherit this configuration.
    Overrides:
    
    setDefaultTimestamp in class Statement
    
    Parameters:
    
    defaultTimestamp - the default timestamp for this query (must be strictly positive).
    
    Returns:
    
    this Statement object.
    
    See Also:
    
    Cluster.Builder.withTimestampGenerator(TimestampGenerator)
  - getDefaultTimestamp
```
public long getDefaultTimestamp()
```
    Description copied from class: Statement
    
    The default timestamp for this query.
    
    Overrides:
    
    getDefaultTimestamp in class Statement
    
    Returns:
    
    the default timestamp (in microseconds since the epoch).
  - setReadTimeoutMillis
```
public Statement setReadTimeoutMillis(int readTimeoutMillis)
```
    Description copied from class: Statement
    
    Overrides the default per-host read timeout (SocketOptions.getReadTimeoutMillis()) for this statement.
    You should override this only for statements for which the coordinator may allow a longer server-side timeout (for example aggregation queries).
    Note that unlike other configuration, when this statement is prepared BoundStatements created off of PreparedStatement do not inherit this configuration.
    
    Overrides:
    
    setReadTimeoutMillis in class Statement
    
    Parameters:
    
    readTimeoutMillis - the timeout to set. Negative values are not allowed. If it is 0, the read timeout will be disabled for this statement.
    
    Returns:
    
    this Statement object.
  - getReadTimeoutMillis
```
public int getReadTimeoutMillis()
```
    Description copied from class: Statement
    
    Return the per-host read timeout that was set for this statement.
    
    Overrides:
    
    getReadTimeoutMillis in class Statement
    
    Returns:
    
    the timeout. Note that a negative value means that the default SocketOptions.getReadTimeoutMillis() will be used.
  - setPagingState
```
public Statement setPagingState(PagingState pagingState,
                                CodecRegistry codecRegistry)
```
    Description copied from class: Statement
    Sets the paging state.
    This will cause the next execution of this statement to fetch results from a given page, rather than restarting from the beginning.
    You get the paging state from a previous execution of the statement (see ExecutionInfo.getPagingState(). This is typically used to iterate in a "stateless" manner (e.g. across HTTP requests):
```
 Statement st = new SimpleStatement("your query");
 ResultSet rs = session.execute(st.setFetchSize(20));
 int available = rs.getAvailableWithoutFetching();
 for (int i = 0; i < available; i++) {
     Row row = rs.one();
     // Do something with row (e.g. display it to the user...)
 }
 // Get state and serialize as string or byte[] to store it for the next execution
 // (e.g. pass it as a parameter in the "next page" URI)
 PagingState pagingState = rs.getExecutionInfo().getPagingState();
 String savedState = pagingState.toString();

 // Next execution:
 // Get serialized state back (e.g. get URI parameter)
 String savedState = ...
 Statement st = new SimpleStatement("your query");
 st.setPagingState(PagingState.fromString(savedState));
 ResultSet rs = session.execute(st.setFetchSize(20));
 int available = rs.getAvailableWithoutFetching();
 for (int i = 0; i < available; i++) {
     ...
 }
 
```
    The paging state can only be reused between perfectly identical statements (same query string, same bound parameters). Altering the contents of the paging state or trying to set it on a different statement will cause this method to fail.
    Note that, due to internal implementation details, the paging state is not portable across native protocol versions (see the online documentation for more explanations about the native protocol). This means that PagingState instances generated with an old version won't work with a higher version. If that is a problem for you, consider using the "unsafe" API (see Statement.setPagingStateUnsafe(byte[])).
    Overrides:
    
    setPagingState in class Statement
    
    Parameters:
    
    pagingState - the paging state to set, or null to remove any state that was previously set on this statement.
    
    codecRegistry - the codec registry that will be used if this method needs to serialize the statement's values in order to check that the paging state matches.
    
    Returns:
    
    this Statement object.
    
    See Also:
    
    Statement.setPagingState(PagingState)
  - setPagingState
```
public Statement setPagingState(PagingState pagingState)
```
    Description copied from class: Statement
    Sets the paging state.
    This method calls Statement.setPagingState(PagingState, CodecRegistry) with CodecRegistry.DEFAULT_INSTANCE. Whether you should use this or the other variant depends on the type of statement this is called on:
    - for a BoundStatement, the codec registry isn't actually needed, so it's always safe to use this method;
    - for a SimpleStatement or BuiltStatement, you can use this method if you use no custom codecs, or if your custom codecs are registered with the default registry. Otherwise, use the other method and provide the registry that contains your codecs.
    Overrides:
    
    setPagingState in class Statement
    
    Parameters:
    
    pagingState - the paging state to set, or null to remove any state that was previously set on this statement.
  - setPagingStateUnsafe
```
public Statement setPagingStateUnsafe(byte[] pagingState)
```
    Description copied from class: Statement
    
    Sets the paging state.
    Contrary to Statement.setPagingState(PagingState), this method takes the "raw" form of the paging state (previously extracted with ExecutionInfo.getPagingStateUnsafe(). It won't validate that this statement matches the one that the paging state was extracted from. If the paging state was altered in any way, you will get unpredictable behavior from Cassandra (ranging from wrong results to a query failure). If you decide to use this variant, it is strongly recommended to add your own validation (for example, signing the raw state with a private key).
    
    Overrides:
    
    setPagingStateUnsafe in class Statement
    
    Parameters:
    
    pagingState - the paging state to set, or null to remove any state that was previously set on this statement.
    
    Returns:
    
    this Statement object.
  - getPagingState
```
public ByteBuffer getPagingState()
```
  - setIdempotent
```
public Statement setIdempotent(boolean idempotent)
```
    Description copied from class: Statement
    
    Sets whether this statement is idempotent.
    See Statement.isIdempotent() for more explanations about this property.
    
    Overrides:
    
    setIdempotent in class Statement
    
    Parameters:
    
    idempotent - the new value.
    
    Returns:
    
    this Statement object.
  - isIdempotent
```
public Boolean isIdempotent()
```
    Description copied from class: Statement
    Whether this statement is idempotent, i.e. whether it can be applied multiple times without changing the result beyond the initial application.
    If a statement is not idempotent, the driver will ensure that it never gets executed more than once, which means:
    - avoiding retries on write timeouts or request errors;
    - never scheduling speculative executions.
    (this behavior is implemented in the driver internals, the corresponding policies will not even be invoked).
    Note that this method can return null, in which case the driver will default to QueryOptions.getDefaultIdempotence().
    By default, this method returns null for all statements, except for
    - BuiltStatement - value will be inferred from the query: if it updates counters, prepends/appends to a list, or uses a function call or QueryBuilder.raw(String) anywhere in an inserted value, the result will be false; otherwise it will be true.
    - Batch and BatchStatement:
      
      If any statement in batch has isIdempotent() false - return false
      If no statements with isIdempotent() false, but some have isIdempotent() null - return null
      Otherwise - return true
    In all cases, calling Statement.setIdempotent(boolean) forces a value that overrides calculated value.
    Note that when a statement is prepared (Session.prepare(String)), its idempotence flag will be propagated to all PreparedStatements created from it.
    Overrides:
    
    isIdempotent in class Statement
    
    Returns:
    
    whether this statement is idempotent, or null to use QueryOptions.getDefaultIdempotence().
  - isIdempotentWithDefault
```
public boolean isIdempotentWithDefault(QueryOptions queryOptions)
```
  - getOutgoingPayload
```
public Map<String,ByteBuffer> getOutgoingPayload()
```
    Description copied from class: Statement
    
    Returns this statement's outgoing payload. Each time this statement is executed, this payload will be included in the query request.
    This method returns null if no payload has been set, otherwise it always returns immutable maps.
    This feature is only available with ProtocolVersion.V4 or above. Trying to include custom payloads in requests sent by the driver under lower protocol versions will result in an UnsupportedFeatureException (wrapped in a NoHostAvailableException).
    
    Overrides:
    
    getOutgoingPayload in class Statement
    
    Returns:
    
    the outgoing payload to include with this statement, or null if no payload has been set.
  - setOutgoingPayload
```
public Statement setOutgoingPayload(Map<String,ByteBuffer> payload)
```
    Description copied from class: Statement
    
    Set the given outgoing payload on this statement. Each time this statement is executed, this payload will be included in the query request.
    This method makes a defensive copy of the given map, but its values remain inherently mutable. Care should be taken not to modify the original map once it is passed to this method.
    This feature is only available with ProtocolVersion.V4 or above. Trying to include custom payloads in requests sent by the driver under lower protocol versions will result in an UnsupportedFeatureException (wrapped in a NoHostAvailableException).
    
    Overrides:
    
    setOutgoingPayload in class Statement
    
    Parameters:
    
    payload - the outgoing payload to include with this statement, or null to clear any previously entered payload.
    
    Returns:
    
    this Statement object.
  - requestSizeInBytes
```
public int requestSizeInBytes(ProtocolVersion protocolVersion,
                              CodecRegistry codecRegistry)
```
    Description copied from class: Statement
    
    Returns the number of bytes required to encode this statement.
    The calculated size may be overestimated by a few bytes, but is never underestimated. If the size cannot be calculated, this method returns -1.
    Note that the returned value is not cached, but instead recomputed at every method call.
    
    Overrides:
    
    requestSizeInBytes in class Statement
    
    Returns:
    
    the number of bytes required to encode this statement.
  - getHost
```
public Host getHost()
```
    Overrides:
    
    getHost in class Statement
    
    Returns:
    
    The host configured on this statement, or null if none is configured.
    
    See Also:
    
    Statement.setHost(Host)
  - setHost
```
public Statement setHost(Host host)
```
    Description copied from class: Statement
    Sets the Host that should handle this query.
    In the general case, use of this method is heavily discouraged and should only be used in the following cases:
    1. Querying node-local tables, such as tables in the system and system_views keyspaces.
    2. Applying a series of schema changes, where it may be advantageous to execute schema changes in sequence on the same node.
    Configuring a specific host causes the configured LoadBalancingPolicy to be completely bypassed. However, if the load balancing policy dictates that the host is at distance HostDistance.IGNORED or there is no active connectivity to the host, the request will fail with a NoHostAvailableException.
    Note that unlike other configuration, when this statement is prepared BoundStatements created off of PreparedStatement do not inherit this configuration.
    Overrides:
    
    setHost in class Statement
    
    Parameters:
    
    host - The host that should be used to handle executions of this statement or null to delegate to the configured load balancing policy.
    
    Returns:
    
    this Statement object.

Class StatementWrapper

Field Summary

Fields inherited from class com.datastax.driver.core.Statement

Constructor Summary

Method Summary

Methods inherited from class com.datastax.driver.core.Statement

Methods inherited from class java.lang.Object

Constructor Detail

StatementWrapper

Method Detail

setConsistencyLevel

getConsistencyLevel

setSerialConsistencyLevel

getSerialConsistencyLevel

enableTracing

disableTracing

isTracing

getRoutingKey

getKeyspace

setRetryPolicy

getRetryPolicy

setFetchSize

getFetchSize

setDefaultTimestamp

getDefaultTimestamp

setReadTimeoutMillis

getReadTimeoutMillis

setPagingState

setPagingState

setPagingStateUnsafe

getPagingState

setIdempotent

isIdempotent

isIdempotentWithDefault

getOutgoingPayload

setOutgoingPayload

requestSizeInBytes

getHost

setHost