com.datastax.driver.core

Class Metadata

java.lang.Object

com.datastax.driver.core.Metadata

public class Metadata
extends Object

Keeps metadata on the connected cluster, including known nodes and schema definitions.

Method Summary

Modifier and Type	Method and Description
boolean	checkSchemaAgreement() Checks whether hosts that are currently up agree on the schema definition.
String	exportSchemaAsString() Returns a String containing CQL queries representing the schema of this cluster.
Set<Host>	getAllHosts() Returns the known hosts of this cluster.
String	getClusterName() The Cassandra name for the cluster connect to.
KeyspaceMetadata	getKeyspace(String keyspace) Returns the metadata of a keyspace given its name.
List<KeyspaceMetadata>	getKeyspaces() Returns a list of all the defined keyspaces.
String	getPartitioner() The partitioner in use as reported by the Cassandra nodes.
Set<Host>	getReplicas(String keyspace, ByteBuffer partitionKey) Returns the set of hosts that are replica for a given partition key.
Set<Host>	getReplicas(String keyspace, TokenRange range) Returns the set of hosts that are replica for a given token range.
Set<TokenRange>	getTokenRanges() Returns the token ranges that define data distribution in the ring.
Set<TokenRange>	getTokenRanges(String keyspace, Host host) Returns the token ranges that are replicated on the given host, for the given keyspace.
Token	newToken(String tokenStr) Builds a new Token from its string representation, according to the partitioner reported by the Cassandra nodes.
TokenRange	newTokenRange(Token start, Token end) Builds a new TokenRange.
TupleType	newTupleType(DataType... types) Creates a tuple type given a list of types.
static String	quote(String id) Quote a keyspace, table or column identifier to make it case sensitive.

Methods inherited from class java.lang.Object

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

Method Detail

quote

public static String quote(String id)

Quote a keyspace, table or column identifier to make it case sensitive.

CQL identifiers, including keyspace, table and column ones, are case insensitive by default. Case sensitive identifiers can however be provided by enclosing the identifier in double quotes (see the CQL documentation for details). If you are using case sensitive identifiers, this method can be used to enclose such identifier in double quotes, making it case sensitive.

Parameters:

id - the keyspace or table identifier.

Returns:

id enclosed in double-quotes, for use in methods like getReplicas(java.lang.String, java.nio.ByteBuffer), getKeyspace(java.lang.String), KeyspaceMetadata.getTable(java.lang.String) or even Cluster.connect(String).

getTokenRanges

public Set<TokenRange> getTokenRanges()

Returns the token ranges that define data distribution in the ring.

Note that this information is refreshed asynchronously by the control connection, when schema or ring topology changes. It might occasionally be stale.

Returns:

the token ranges.

getTokenRanges

public Set<TokenRange> getTokenRanges(String keyspace,
                                      Host host)

Returns the token ranges that are replicated on the given host, for the given keyspace.

Note that this information is refreshed asynchronously by the control connection, when schema or ring topology changes. It might occasionally be stale (or even empty).

Parameters:

keyspace - the name of the keyspace to get token ranges for.

host - the host.

Returns:

the (immutable) set of token ranges for host as known by the driver.

getReplicas

public Set<Host> getReplicas(String keyspace,
                             ByteBuffer partitionKey)

Returns the set of hosts that are replica for a given partition key.

Note that this information is refreshed asynchronously by the control connection, when schema or ring topology changes. It might occasionally be stale (or even empty).

Parameters:

keyspace - the name of the keyspace to get replicas for.

partitionKey - the partition key for which to find the set of replica.

Returns:

the (immutable) set of replicas for partitionKey as known by the driver.

getReplicas

public Set<Host> getReplicas(String keyspace,
                             TokenRange range)

Returns the set of hosts that are replica for a given token range.

Note that this information is refreshed asynchronously by the control connection, when schema or ring topology changes. It might occasionally be stale (or even empty).

Parameters:

keyspace - the name of the keyspace to get replicas for.

range - the token range.

Returns:

the (immutable) set of replicas for range as known by the driver.

getClusterName

public String getClusterName()

The Cassandra name for the cluster connect to.

Returns:

the Cassandra name for the cluster connect to.

getPartitioner

public String getPartitioner()

The partitioner in use as reported by the Cassandra nodes.

Returns:

the partitioner in use as reported by the Cassandra nodes.

getAllHosts

public Set<Host> getAllHosts()

Returns the known hosts of this cluster.

Returns:

A set will all the know host of this cluster.

checkSchemaAgreement

public boolean checkSchemaAgreement()

Checks whether hosts that are currently up agree on the schema definition.

This method performs a one-time check only, without any form of retry; therefore Cluster.Builder.withMaxSchemaAgreementWaitSeconds(int) does not apply in this case.

Returns:

true if all hosts agree on the schema; false if they don't agree, or if the check could not be performed (for example, if the control connection is down).

getKeyspace

public KeyspaceMetadata getKeyspace(String keyspace)

Returns the metadata of a keyspace given its name.

Parameters:

keyspace - the name of the keyspace for which metadata should be returned.

Returns:

the metadata of the requested keyspace or null if keyspace is not a known keyspace.

getKeyspaces

public List<KeyspaceMetadata> getKeyspaces()

Returns a list of all the defined keyspaces.

Returns:

a list of all the defined keyspaces.

exportSchemaAsString

public String exportSchemaAsString()

Returns a String containing CQL queries representing the schema of this cluster. In other words, this method returns the queries that would allow to recreate the schema of this cluster. Note that the returned String is formatted to be human readable (for some definition of human readable at least).

Returns:

the CQL queries representing this cluster schema as a {code String}.

newTupleType

public TupleType newTupleType(DataType... types)

Creates a tuple type given a list of types.

Parameters:

types - the types for the tuple type.

Returns:

the newly created tuple type.

newToken

public Token newToken(String tokenStr)

Builds a new Token from its string representation, according to the partitioner reported by the Cassandra nodes.

Parameters:

tokenStr - the string representation.

Returns:

the token.

newTokenRange

public TokenRange newTokenRange(Token start,
                                Token end)

Builds a new TokenRange.

Parameters:

start - the start token.

end - the end token.

Returns:

the range.