class Metadata

Constructor

new

Metadata

(ClientOptions options, ControlConnection controlConnection)

Represents cluster and schema information. The metadata class acts as a internal state of the driver.

Parameters:
Name Type Description
options ClientOptions
controlConnection ControlConnection

Control connection used to retrieve information.

Methods

clearPrepared

()

Clears the internal state related to the prepared statements. Following calls to the Client using the prepare flag will re-prepare the statements.

getAggregate

(String keyspaceName, String name, Array<String> or Array<{code, info}> signature, [function callback])

Gets a definition of CQL aggregate for a given name and signature.

If a callback is provided, the callback is invoked when the metadata retrieval completes. Otherwise, it returns a Promise.

When trying to retrieve the same aggregate definition concurrently, it will query once and invoke all callbacks with the retrieved information.

Parameters:
Name Type Description
keyspaceName String

Name of the keyspace
name String

Name of the aggregate
signature Array<String> or Array<{code, info}>

Array of types of the parameters.
callback optional function

The callback with the err as a first parameter and the Aggregate as second parameter.

getAggregates

(String keyspaceName, String name, [function callback])

Gets the definition of CQL aggregate for a given name.

If a callback is provided, the callback is invoked when the metadata retrieval completes. Otherwise, it returns a Promise.

When trying to retrieve the same aggregates definition concurrently, it will query once and invoke all callbacks with the retrieved information.

Parameters:
Name Type Description
keyspaceName String

Name of the keyspace
name String

Name of the Function
callback optional function

The callback with the err as a first parameter and the array of Aggregate as second parameter.

getFunction

(String keyspaceName, String name, Array<String> or Array<{code, info}> signature, [function callback])

Gets a definition of CQL function for a given name and signature.

If a callback is provided, the callback is invoked when the metadata retrieval completes. Otherwise, it returns a Promise.

When trying to retrieve the same function definition concurrently, it will query once and invoke all callbacks with the retrieved information.

Parameters:
Name Type Description
keyspaceName String

Name of the keyspace
name String

Name of the Function
signature Array<String> or Array<{code, info}>

Array of types of the parameters.
callback optional function

The callback with the err as a first parameter and the SchemaFunction as second parameter.

getFunctions

(String keyspaceName, String name, [function callback])

Gets the definition of CQL functions for a given name.

If a callback is provided, the callback is invoked when the metadata retrieval completes. Otherwise, it returns a Promise.

When trying to retrieve the same function definition concurrently, it will query once and invoke all callbacks with the retrieved information.

Parameters:
Name Type Description
keyspaceName String

Name of the keyspace.
name String

Name of the Function.
callback optional function

The callback with the err as a first parameter and the array of SchemaFunction as second parameter.

getMaterializedView

(String keyspaceName, String name, [function callback])

Gets the definition of a CQL materialized view for a given name.

If a callback is provided, the callback is invoked when the metadata retrieval completes. Otherwise, it returns a Promise.

Note that, unlike the rest of the Metadata methods, this method does not cache the result for following calls, as the current version of the Cassandra native protocol does not support schema change events for materialized views. Each call to this method will produce one or more queries to the cluster.

Parameters:
Name Type Description
keyspaceName String

Name of the keyspace
name String

Name of the materialized view
callback optional function

The callback with the err as a first parameter and the MaterializedView as second parameter.

getReplicas

(String keyspaceName, Buffer, Token or TokenRange token)

Gets the host list representing the replicas that contain the given partition key, token or token range.

It uses the pre-loaded keyspace metadata to retrieve the replicas for a token for a given keyspace. When the keyspace metadata has not been loaded, it returns null.

Parameters:
Name Type Description
keyspaceName String
token Buffer, Token or TokenRange

Can be Buffer (serialized partition key), Token or TokenRange
Returns:
Type Description
Array

getTable

(String keyspaceName, String name, [function callback])

Gets the definition of a table.

If a callback is provided, the callback is invoked when the metadata retrieval completes. Otherwise, it returns a Promise.

When trying to retrieve the same table definition concurrently, it will query once and invoke all callbacks with the retrieved information.

Parameters:
Name Type Description
keyspaceName String

Name of the keyspace.
name String

Name of the Table.
callback optional function

The callback with the err as a first parameter and the TableMetadata as second parameter.

getTokenRanges

()

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

Returns:
Type Description
Set<TokenRange>

The ranges of the ring.

getTokenRangesForHost

(String keyspaceName, Host host)

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

Parameters:
Name Type Description
keyspaceName String

The name of the keyspace to get ranges for.
host Host

The host.
Returns:
Type Description
Set<TokenRange> or null

Ranges for the keyspace on this host or null if keyspace isn’t found.

getTrace

(Uuid traceId, [Number consistency], [function callback])

Gets the trace session generated by Cassandra when query tracing is enabled for the query. The trace itself is stored in Cassandra in the sessions and events table in the system_traces keyspace and can be retrieve manually using the trace identifier.

If a callback is provided, the callback is invoked when the metadata retrieval completes. Otherwise, it returns a Promise.

Parameters:
Name Type Description
traceId Uuid

Identifier of the trace session.
consistency optional Number

The consistency level to obtain the trace.
callback optional function

The callback with the err as first parameter and the query trace as second parameter.

getUdt

(String keyspaceName, String name, [function callback])

Gets the definition of an user-defined type.

If a callback is provided, the callback is invoked when the metadata retrieval completes. Otherwise, it returns a Promise.

When trying to retrieve the same UDT definition concurrently, it will query once and invoke all callbacks with the retrieved information.

Parameters:
Name Type Description
keyspaceName String

Name of the keyspace.
name String

Name of the UDT.
callback optional function

The callback to invoke when retrieval completes.

newToken

(Array<Buffer>, Buffer or String components)

Constructs a Token from the input buffer(s) or string input. If a string is passed in it is assumed this matches the token representation reported by cassandra.

Parameters:
Name Type Description
components Array<Buffer>, Buffer or String
Returns:
Type Description
Token

constructed token from the input buffer.

newTokenRange

(Token start, Token end)

Constructs a TokenRange from the given start and end tokens.

Parameters:
Name Type Description
start Token
end Token
Returns:
Type Description

TokenRange build range spanning from start (exclusive) to end (inclusive).

refreshKeyspace

(String name, [function callback])

Gets the keyspace metadata information and updates the internal state of the driver.

If a callback is provided, the callback is invoked when the keyspaces metadata refresh completes. Otherwise, it returns a Promise.

Parameters:
Name Type Description
name String

Name of the keyspace.
callback optional function

Optional callback.

refreshKeyspaces

([Boolean or function waitReconnect], [function callback])

Gets the metadata information of all the keyspaces and updates the internal state of the driver.

If a callback is provided, the callback is invoked when the keyspace metadata refresh completes. Otherwise, it returns a Promise.

Parameters:
Name Type Description
waitReconnect optional Boolean or function

Determines if it should wait for reconnection in case the control connection is not connected at the moment. Default: true.
callback optional function

Optional callback.