Reference configuration

The following is a copy of the reference.conf file matching the version of this documentation. It is packaged in the java-driver-core JAR artifact, and used at runtime to provide the default values for all configuration options (in the sources, it can be found under core/src/main/resources).

See the configuration page for more explanations.

# Reference configuration for the DataStax Java driver for Apache Cassandra®.
#
# Unless you use a custom mechanism to load your configuration (see
# SessionBuilder.withConfigLoader), all the values declared here will be used as defaults. You can
# place your own `application.conf` in the classpath to override them.
#
# Options are classified into two categories:
# - basic: what is most likely to be customized first when kickstarting a new application.
# - advanced: more elaborate tuning options, or "expert"-level customizations.
#
# This file is in HOCON format, see https://github.com/typesafehub/config/blob/master/HOCON.md.
datastax-java-driver {

  # BASIC OPTIONS ----------------------------------------------------------------------------------

  # The contact points to use for the initial connection to the cluster.
  #
  # These are addresses of Cassandra nodes that the driver uses to discover the cluster topology.
  # Only one contact point is required (the driver will retrieve the address of the other nodes
  # automatically), but it is usually a good idea to provide more than one contact point, because if
  # that single contact point is unavailable, the driver cannot initialize itself correctly.
  #
  # This must be a list of strings with each contact point specified as "host:port". If the host is
  # a DNS name that resolves to multiple A-records, all the corresponding addresses will be used. Do
  # not use "localhost" as the host name (since it resolves to both IPv4 and IPv6 addresses on some
  # platforms).
  #
  # Note that Cassandra 3 and below requires all nodes in a cluster to share the same port (see
  # CASSANDRA-7544).
  #
  # Contact points can also be provided programmatically when you build a cluster instance. If both
  # are specified, they will be merged. If both are absent, the driver will default to
  # 127.0.0.1:9042.
  #
  # Required: no
  # Modifiable at runtime: no
  # Overridable in a profile: no
  // basic.contact-points = [ "127.0.0.1:9042", "127.0.0.2:9042" ]

  # A name that uniquely identifies the driver instance created from this configuration. This is
  # used as a prefix for log messages and metrics.
  #
  # If this option is absent, the driver will generate an identifier composed of the letter 's'
  # followed by an incrementing counter. If you provide a different value, try to keep it short to
  # keep the logs readable. Also, make sure it is unique: reusing the same value will not break the
  # driver, but it will mix up the logs and metrics.
  #
  # Required: no
  # Modifiable at runtime: no
  # Overridable in a profile: no
  // basic.session-name = my_session

  # The name of the keyspace that the session should initially be connected to.
  #
  # This expects the same format as in a CQL query: case-sensitive names must be quoted (note that
  # the quotes must be escaped in HOCON format). For example:
  #    session-keyspace = case_insensitive_name
  #    session-keyspace = \"CaseSensitiveName\"
  #
  # If this option is absent, the session won't be connected to any keyspace, and you'll have to
  # either qualify table names in your queries, or use the per-query keyspace feature available in
  # Cassandra 4 and above (see Request.getKeyspace()).
  #
  # This can also be provided programatically in CqlSessionBuilder.
  #
  # Required: no
  # Modifiable at runtime: no
  # Overridable in a profile: no
  // basic.session-keyspace = my_keyspace

  # How often the driver tries to reload the configuration.
  #
  # To disable periodic reloading, set this to 0.
  #
  # Required: yes (unless you pass a different ConfigLoader to the session builder).
  # Modifiable at runtime: yes, the new value will be used after the next time the configuration
  #   gets reloaded.
  # Overridable in a profile: no
  basic.config-reload-interval = 5 minutes

  basic.request {
    # How long the driver waits for a request to complete. This is a global limit on the duration of
    # a session.execute() call, including any internal retries the driver might do.
    #
    # By default, this value is set pretty high to ensure that DDL queries don't time out, in order
    # to provide the best experience for new users trying the driver with the out-of-the-box
    # configuration.
    # For any serious deployment, we recommend that you use separate configuration profiles for DDL
    # and DML; you can then set the DML timeout much lower (down to a few milliseconds if needed).
    #
    # Note that, because timeouts are scheduled on the driver's timer thread, the duration specified
    # here must be greater than the timer tick duration defined by the
    # advanced.netty.timer.tick-duration setting (see below). If that is not the case, timeouts will
    # not be triggered as timely as desired.
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for requests issued after the change.
    # Overridable in a profile: yes
    timeout = 2 seconds

    # The consistency level.
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for requests issued after the change.
    # Overridable in a profile: yes
    consistency = LOCAL_ONE

    # The page size. This controls how many rows will be retrieved simultaneously in a single
    # network roundtrip (the goal being to avoid loading too many results in memory at the same
    # time). If there are more results, additional requests will be used to retrieve them (either
    # automatically if you iterate with the sync API, or explicitly with the async API's
    # fetchNextPage method).
    # If the value is 0 or negative, it will be ignored and the request will not be paged.
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for requests issued after the change.
    # Overridable in a profile: yes
    page-size = 5000

    # The serial consistency level.
    # The allowed values are SERIAL and LOCAL_SERIAL.
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for requests issued after the change.
    # Overridable in a profile: yes
    serial-consistency = SERIAL

    # The default idempotence of a request, that will be used for all `Request` instances where
    # `isIdempotent()` returns null.
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for requests issued after the change.
    # Overridable in a profile: yes
    default-idempotence = false
  }

  # The policy that decides the "query plan" for each query; that is, which nodes to try as
  # coordinators, and in which order.
  #
  # Required: yes
  # Modifiable at runtime: no (but custom implementations may elect to watch configuration changes
  #   and allow child options to be changed at runtime).
  # Overridable in a profile: yes. Note that the driver creates as few instances as possible: if a
  #   named profile inherits from the default profile, or if two sibling profiles have the exact
  #   same configuration, they will share a single policy instance at runtime.
  #   If there are multiple load balancing policies in a single driver instance, they work together
  #   in the following way:
  #   - each request gets a query plan from its profile's policy (or the default policy if the
  #     request has no profile, or the profile does not override the policy).
  #   - when the policies assign distances to nodes, the driver uses the closest assigned distance
  #     for any given node.
  basic.load-balancing-policy {
    # The class of the policy. If it is not qualified, the driver assumes that it resides in the
    # package com.datastax.oss.driver.internal.core.loadbalancing.
    #
    # The driver provides a single implementation out of the box: DefaultLoadBalancingPolicy.
    #
    # You can also specify a custom class that implements LoadBalancingPolicy and has a public
    # constructor with two arguments: the DriverContext and a String representing the profile name.
    class = DefaultLoadBalancingPolicy

    # The datacenter that is considered "local": the default policy will only include nodes from
    # this datacenter in its query plans.
    #
    # This option can only be absent if you specified no contact points: in that case, the driver
    # defaults to 127.0.0.1:9042, and that node's datacenter is used as the local datacenter.
    #
    # As soon as you provide contact points (either through the configuration or through the cluster
    # builder), you must define the local datacenter explicitly, and initialization will fail if
    # this property is absent. In addition, all contact points should be from this datacenter;
    # warnings will be logged for nodes that are from a different one.
    #
    # This can also be specified programmatically with SessionBuilder.withLocalDatacenter. If both
    # are specified, the programmatic value takes precedence.
    // local-datacenter = datacenter1

    # A custom filter to include/exclude nodes.
    #
    # This option is not required; if present, it must be the fully-qualified name of a class that
    # implements `java.util.function.Predicate<Node>`, and has a public constructor taking a single
    # `DriverContext` argument.
    #
    # Alternatively, you can pass an instance of your filter to
    # CqlSession.builder().withNodeFilter(). In that case, this option will be ignored.
    #
    # The predicate's `test(Node)` method will be invoked each time the policy processes a
    # topology or state change: if it returns false, the node will be set at distance IGNORED
    # (meaning the driver won't ever connect to it), and never included in any query plan.
    // filter.class=
  }


  # ADVANCED OPTIONS -------------------------------------------------------------------------------

  advanced.connection {
    # The timeout to use for internal queries that run as part of the initialization process, just
    # after we open a connection. If this timeout fires, the initialization of the connection will
    # fail. If this is the first connection ever, the driver will fail to initialize as well,
    # otherwise it will retry the connection later.
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for connections created after the
    #   change.
    # Overridable in a profile: no
    init-query-timeout = 500 milliseconds

    # The timeout to use when the driver changes the keyspace on a connection at runtime (this
    # happens when the client issues a `USE ...` query, and all connections belonging to the current
    # session need to be updated).
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for connections created after the
    #   change.
    # Overridable in a profile: no
    set-keyspace-timeout = ${datastax-java-driver.advanced.connection.init-query-timeout}

    # The driver maintains a connection pool to each node, according to the distance assigned to it
    # by the load balancing policy. If the distance is IGNORED, no connections are maintained.
    pool {
      local {
        # The number of connections in the pool.
        #
        # Required: yes
        # Modifiable at runtime: yes; when the change is detected, all active pools will be notified
        #   and will adjust their size.
        # Overridable in a profile: no
        size = 1
      }
      remote {
        size = 1
      }
    }

    # The maximum number of requests that can be executed concurrently on a connection. This must be
    # between 1 and 32768.
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for connections created after the
    #   change.
    # Overridable in a profile: no
    max-requests-per-connection = 1024

    # The maximum number of "orphaned" requests before a connection gets closed automatically.
    #
    # Sometimes the driver writes to a node but stops listening for a response (for example if the
    # request timed out, or was completed by another node). But we can't safely reuse the stream id
    # on this connection until we know for sure that the server is done with it. Therefore the id is
    # marked as "orphaned" until we get a response from the node.
    #
    # If the response never comes (or is lost because of a network issue), orphaned ids can
    # accumulate over time, eventually affecting the connection's throughput. So we monitor them
    # and close the connection above a given threshold (the pool will replace it).
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for connections created after the
    #   change.
    # Overridable in a profile: no
    max-orphan-requests = 24576

    # Whether to log non-fatal errors when the driver tries to open a new connection.
    #
    # This error as recoverable, as the driver will try to reconnect according to the reconnection
    # policy. Therefore some users see them as unnecessary clutter in the logs. On the other hand,
    # those logs can be handy to debug a misbehaving node.
    #
    # Note that some type of errors are always logged, regardless of this option:
    # - protocol version mismatches (the node gets forced down)
    # - when the cluster name in system.local doesn't match the other nodes (the node gets forced
    #   down)
    # - authentication errors (will be retried)
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for connections created after the
    #   change.
    # Overridable in a profile: no
    warn-on-init-error = true
  }

  # Whether to schedule reconnection attempts if all contact points are unreachable on the first
  # initialization attempt.
  #
  # If this is true, the driver will retry according to the reconnection policy. The
  # `SessionBuilder.build()` call -- or the future returned by `SessionBuilder.buildAsync()` --
  # won't complete until a contact point has been reached.
  #
  # If this is false and no contact points are available, the driver will fail with an
  # AllNodesFailedException.
  #
  # Required: yes
  # Modifiable at runtime: no
  # Overridable in a profile: no
  advanced.reconnect-on-init = false

  # The policy that controls how often the driver tries to re-establish connections to down nodes.
  #
  # Required: yes
  # Modifiable at runtime: no (but custom implementations may elect to watch configuration changes
  #   and allow child options to be changed at runtime).
  # Overridable in a profile: no
  advanced.reconnection-policy {
    # The class of the policy. If it is not qualified, the driver assumes that it resides in the
    # package com.datastax.oss.driver.internal.core.connection.
    #
    # The driver provides two implementations out of the box: ExponentialReconnectionPolicy and
    # ConstantReconnectionPolicy.
    #
    # You can also specify a custom class that implements ReconnectionPolicy and has a public
    # constructor with a DriverContext argument.
    class = ExponentialReconnectionPolicy

    # ExponentialReconnectionPolicy starts with the base delay, and doubles it after each failed
    # reconnection attempt, up to the maximum delay (after that it stays constant).
    #
    # ConstantReconnectionPolicy only uses the base-delay value, the interval never changes.
    base-delay = 1 second
    max-delay = 60 seconds
  }

  # The policy that controls if the driver retries requests that have failed on one node.
  #
  # Required: yes
  # Modifiable at runtime: no (but custom implementations may elect to watch configuration changes
  #   and allow child options to be changed at runtime).
  # Overridable in a profile: yes. Note that the driver creates as few instances as possible: if a
  #   named profile inherits from the default profile, or if two sibling profiles have the exact
  #   same configuration, they will share a single policy instance at runtime.
  advanced.retry-policy {
    # The class of the policy. If it is not qualified, the driver assumes that it resides in the
    # package com.datastax.oss.driver.internal.core.retry.
    #
    # The driver provides a single implementation out of the box: DefaultRetryPolicy.
    #
    # You can also specify a custom class that implements RetryPolicy and has a public constructor
    # with two arguments: the DriverContext and a String representing the profile name.
    class = DefaultRetryPolicy
  }

  # The policy that controls if the driver pre-emptively tries other nodes if a node takes too long
  # to respond.
  #
  # Required: yes
  # Modifiable at runtime: no (but custom implementations may elect to watch configuration changes
  #   and allow child options to be changed at runtime).
  # Overridable in a profile: yes. Note that the driver creates as few instances as possible: if a
  #   named profile inherits from the default profile, or if two sibling profiles have the exact
  #   same configuration, they will share a single policy instance at runtime.
  advanced.speculative-execution-policy {
    # The class of the policy. If it is not qualified, the driver assumes that it resides in the
    # package com.datastax.oss.driver.internal.core.specex.
    #
    # The following implementations are available out of the box:
    # - NoSpeculativeExecutionPolicy: never schedule any speculative execution
    # - ConstantSpeculativeExecutionPolicy: schedule executions based on constant delays. This
    #   requires the `max-executions` and `delay` options below.
    #
    # You can also specify a custom class that implements SpeculativeExecutionPolicy and has a
    # public constructor with two arguments: the DriverContext and a String representing the
    # profile name.
    class = NoSpeculativeExecutionPolicy

    # The maximum number of executions (including the initial, non-speculative execution).
    # This must be at least one.
    // max-executions = 3

    # The delay between each execution. 0 is allowed, and will result in all executions being sent
    # simultaneously when the request starts.
    #
    # Note that sub-millisecond precision is not supported, any excess precision information will be
    # dropped; in particular, delays of less than 1 millisecond are equivalent to 0.
    #
    # Also note that, because speculative executions are scheduled on the driver's timer thread,
    # the duration specified here must be greater than the timer tick duration defined by the
    # advanced.netty.timer.tick-duration setting (see below). If that is not the case, speculative
    # executions will not be triggered as timely as desired.
    #
    # This must be positive or 0.
    // delay = 100 milliseconds
  }

  # The component that handles authentication on each new connection.
  #
  # Required: no. If the 'class' child option is absent, no authentication will occur.
  # Modifiable at runtime: no
  # Overridable in a profile: no
  advanced.auth-provider {
    # The class of the provider. If it is not qualified, the driver assumes that it resides in the
    # package com.datastax.oss.driver.internal.core.auth.
    #
    # The driver provides a single implementation out of the box: PlainTextAuthProvider, that uses
    # plain-text credentials. It requires the `username` and `password` options below.
    #
    # You can also specify a custom class that implements AuthProvider and has a public
    # constructor with a DriverContext argument.
    // class = PlainTextAuthProvider

    # Sample configuration for the plain-text provider:
    // username = cassandra
    // password = cassandra
  }

  # The SSL engine factory that will initialize an SSL engine for each new connection to a server.
  #
  # Required: no. If the 'class' child option is absent, SSL won't be activated.
  # Modifiable at runtime: no
  # Overridable in a profile: no
  advanced.ssl-engine-factory {
    # The class of the factory. If it is not qualified, the driver assumes that it resides in the
    # package com.datastax.oss.driver.internal.core.ssl.
    #
    # The driver provides a single implementation out of the box: DefaultSslEngineFactory, that uses
    # the JDK's built-in SSL implementation.
    #
    # You can also specify a custom class that implements SslEngineFactory and has a public
    # constructor with a DriverContext argument.
    // class = DefaultSslEngineFactory

    # Sample configuration for the default SSL factory:
    # The cipher suites to enable when creating an SSLEngine for a connection.
    # This property is optional. If it is not present, the driver won't explicitly enable cipher
    # suites on the engine, which according to the JDK documentations results in "a minimum quality
    # of service".
    // cipher-suites = [ "TLS_RSA_WITH_AES_128_CBC_SHA", "TLS_RSA_WITH_AES_256_CBC_SHA" ]

    # Whether or not to require validation that the hostname of the server certificate's common
    # name matches the hostname of the server being connected to. If not set, defaults to true.
    // hostname-validation = true

    # The locations and passwords used to access truststore and keystore contents.
    # These properties are optional. If either truststore-path or keystore-path are specified,
    # the driver builds an SSLContext from these files.  If neither option is specified, the
    # default SSLContext is used, which is based on system property configuration.
    // truststore-path = /path/to/client.truststore
    // truststore-password = password123
    // keystore-path = /path/to/client.keystore
    // keystore-password = password123
  }

  # The generator that assigns a microsecond timestamp to each request.
  #
  # Required: yes
  # Modifiable at runtime: no (but custom implementations may elect to watch configuration changes
  #   and allow child options to be changed at runtime).
  # Overridable in a profile: yes. Note that the driver creates as few instances as possible: if a
  #   named profile inherits from the default profile, or if two sibling profiles have the exact
  #   same configuration, they will share a single generator instance at runtime.
  advanced.timestamp-generator {
    # The class of the generator. If it is not qualified, the driver assumes that it resides in the
    # package com.datastax.oss.driver.internal.core.time.
    #
    # The driver provides the following implementations out of the box:
    # - AtomicTimestampGenerator: timestamps are guaranteed to be unique across all client threads.
    # - ThreadLocalTimestampGenerator: timestamps that are guaranteed to be unique within each
    #   thread only.
    # - ServerSideTimestampGenerator: do not generate timestamps, let the server assign them.
    #
    # You can also specify a custom class that implements TimestampGenerator and has a public
    # constructor with two arguments: the DriverContext and a String representing the profile name.
    class = AtomicTimestampGenerator

    # To guarantee that queries are applied on the server in the same order as the client issued
    # them, timestamps must be strictly increasing. But this means that, if the driver sends more
    # than one query per microsecond, timestamps will drift in the future. While this could happen
    # occasionally under high load, it should not be a regular occurrence. Therefore the built-in
    # implementations log a warning to detect potential issues.
    drift-warning {
      # How far in the future timestamps are allowed to drift before the warning is logged.
      # If it is undefined or set to 0, warnings are disabled.
      threshold = 1 second

      # How often the warning will be logged if timestamps keep drifting above the threshold.
      interval = 10 seconds
    }

    # Whether to force the driver to use Java's millisecond-precision system clock.
    # If this is false, the driver will try to access the microsecond-precision OS clock via native
    # calls (and fallback to the Java one if the native calls fail).
    # Unless you explicitly want to avoid native calls, there's no reason to change this.
    force-java-clock = false
  }

  # A session-wide component that tracks the outcome of requests.
  #
  # Required: yes
  # Modifiable at runtime: no (but custom implementations may elect to watch configuration changes
  #   and allow child options to be changed at runtime).
  # Overridable in a profile: no
  advanced.request-tracker {
    # The class of the tracker. If it is not qualified, the driver assumes that it resides in the
    # package com.datastax.oss.driver.internal.core.tracker.
    #
    # The driver provides the following implementations out of the box:
    # - NoopRequestTracker: does nothing.
    # - RequestLogger: logs requests (see the parameters below).
    #
    # You can also specify a custom class that implements RequestTracker and has a public
    # constructor with a DriverContext argument.
    class = NoopRequestTracker

    # Parameters for RequestLogger. All of them can be overridden in a profile, and changed at
    # runtime (the new values will be taken into account for requests logged after the change).
    logs {
      # Whether to log successful requests.
      // success.enabled = true

      slow {
        # The threshold to classify a successful request as "slow". If this is unset, all successful
        # requests will be considered as normal.
        // threshold = 1 second

        # Whether to log slow requests.
        // enabled = true
      }

      # Whether to log failed requests.
      // error.enabled = true

      # The maximum length of the query string in the log message. If it is longer than that, it
      # will be truncated.
      // max-query-length = 500

      # Whether to log bound values in addition to the query string.
      // show-values = true

      # The maximum length for bound values in the log message. If the formatted representation of a
      # value is longer than that, it will be truncated.
      // max-value-length = 50

      # The maximum number of bound values to log. If a request has more values, the list of values
      # will be truncated.
      // max-values = 50

      # Whether to log stack traces for failed queries. If this is disabled, the log will just
      # include the exception's string representation (generally the class name and message).
      // show-stack-traces = true
    }
  }

  # A session-wide component that controls the rate at which requests are executed.
  #
  # Implementations vary, but throttlers generally track a metric that represents the level of
  # utilization of the session, and prevent new requests from starting when that metric exceeds a
  # threshold. Pending requests may be enqueued and retried later.
  #
  # From the public API's point of view, this process is mostly transparent: any time that the
  # request is throttled is included in the session.execute() or session.executeAsync() call.
  # Similarly, the request timeout encompasses throttling: the timeout starts ticking before the
  # throttler has started processing the request; a request may time out while it is still in the
  # throttler's queue, before the driver has even tried to send it to a node.
  #
  # The only visible effect is that a request may fail with a RequestThrottlingException, if the
  # throttler has determined that it can neither allow the request to proceed now, nor enqueue it;
  # this indicates that your session is overloaded.
  #
  # Required: yes
  # Modifiable at runtime: no (but custom implementations may elect to watch configuration changes
  #   and allow child options to be changed at runtime).
  # Overridable in a profile: no
  advanced.throttler {
    # The class of the throttler. If it is not qualified, the driver assumes that it resides in
    # the package com.datastax.oss.driver.internal.core.session.throttling.
    #
    # The driver provides the following implementations out of the box:
    #
    # - PassThroughRequestThrottler: does not perform any kind of throttling, all requests are
    #   allowed to proceed immediately. Required options: none.
    #
    # - ConcurrencyLimitingRequestThrottler: limits the number of requests that can be executed in
    #   parallel. Required options: max-concurrent-requests, max-queue-size.
    #
    # - RateLimitingRequestThrottler: limits the request rate per second. Required options:
    #   max-requests-per-second, max-queue-size, drain-interval.
    #
    # You can also specify a custom class that implements RequestThrottler and has a public
    # constructor with a DriverContext argument.
    class = PassThroughRequestThrottler

    # The maximum number of requests that can be enqueued when the throttling threshold is exceeded.
    # Beyond that size, requests will fail with a RequestThrottlingException.
    // max-queue-size = 10000

    # The maximum number of requests that are allowed to execute in parallel.
    # Only used by ConcurrencyLimitingRequestThrottler.
    // max-concurrent-requests = 10000

    # The maximum allowed request rate.
    # Only used by RateLimitingRequestThrottler.
    // max-requests-per-second = 10000

    # How often the throttler attempts to dequeue requests. This is the only way for rate-based
    # throttling, because the completion of an active request does not necessarily free a "slot" for
    # a queued one (the rate might still be too high).
    #
    # You want to set this high enough that each attempt will process multiple entries in the queue,
    # but not delay requests too much. A few milliseconds is probably a happy medium.
    #
    # Only used by RateLimitingRequestThrottler.
    // drain-interval = 10 milliseconds
  }

  # A session-wide component that listens for node state changes. If it is not qualified, the driver
  # assumes that it resides in the package com.datastax.oss.driver.internal.core.metadata.
  #
  # The driver provides a single no-op implementation out of the box: NoopNodeStateListener.
  #
  # You can also specify a custom class that implements NodeStateListener and has a public
  # constructor with a DriverContext argument.
  #
  # Alternatively, you can pass an instance of your listener programmatically with
  # CqlSession.builder().withNodeStateListener(). In that case, this option will be ignored.
  #
  # Required: unless a listener has been provided programmatically
  # Modifiable at runtime: no (but custom implementations may elect to watch configuration changes
  #   and allow child options to be changed at runtime).
  # Overridable in a profile: no
  advanced.node-state-listener.class = NoopNodeStateListener

  # A session-wide component that listens for node state changes. If it is not qualified, the driver
  # assumes that it resides in the package com.datastax.oss.driver.internal.core.metadata.schema.
  #
  # The driver provides a single no-op implementation out of the box: NoopSchemaChangeListener.
  #
  # You can also specify a custom class that implements SchemaChangeListener and has a public
  # constructor with a DriverContext argument.
  #
  # Alternatively, you can pass an instance of your listener programmatically with
  # CqlSession.builder().withSchemaChangeListener(). In that case, this option will be ignored.
  #
  # Required: unless a listener has been provided programmatically
  # Modifiable at runtime: no (but custom implementations may elect to watch configuration changes
  #   and allow child options to be changed at runtime).
  # Overridable in a profile: no
  advanced.schema-change-listener.class = NoopSchemaChangeListener

  # The address translator to use to convert the addresses sent by Cassandra nodes into ones that
  # the driver uses to connect.
  # This is only needed if the nodes are not directly reachable from the driver (for example, the
  # driver is in a different network region and needs to use a public IP, or it connects through a
  # proxy).
  #
  # Required: yes
  # Modifiable at runtime: no
  # Overridable in a profile: no
  advanced.address-translator {
    # The class of the translator. If it is not qualified, the driver assumes that it resides in
    # the package com.datastax.oss.driver.internal.core.addresstranslation.
    #
    # The driver provides the following implementations out of the box:
    # - PassThroughAddressTranslator: returns all addresses unchanged
    #
    # You can also specify a custom class that implements AddressTranslator and has a public
    # constructor with a DriverContext argument.
    class = PassThroughAddressTranslator
  }

  # Whether to resolve the addresses passed to `basic.contact-points`.
  #
  # If this is true, addresses are created with `InetSocketAddress(String, int)`: the host name will
  # be resolved the first time, and the driver will use the resolved IP address for all subsequent
  # connection attempts.
  #
  # If this is false, addresses are created with `InetSocketAddress.createUnresolved()`: the host
  # name will be resolved again every time the driver opens a new connection. This is useful for
  # containerized environments where DNS records are more likely to change over time (note that the
  # JVM and OS have their own DNS caching mechanisms, so you might need additional configuration
  # beyond the driver).
  #
  # This option only applies to the contact points specified in the configuration. It has no effect
  # on:
  # - programmatic contact points passed to SessionBuilder.addContactPoints: these addresses are
  #   built outside of the driver, so it is your responsibility to provide unresolved instances.
  # - dynamically discovered peers: the driver relies on Cassandra system tables, which expose raw
  #   IP addresses. Use a custom address translator to convert them to unresolved addresses (if
  #   you're in a containerized environment, you probably already need address translation anyway).
  #
  # Required: no (defaults to true)
  # Modifiable at runtime: no
  # Overridable in a profile: no
  advanced.resolve-contact-points = true

  advanced.protocol {
    # The native protocol version to use.
    #
    # If this option is absent, the driver looks up the versions of the nodes at startup (by default
    # in system.peers.release_version), and chooses the highest common protocol version.
    # For example, if you have a mixed cluster with Apache Cassandra 2.1 nodes (protocol v3) and
    # Apache Cassandra 3.0 nodes (protocol v3 and v4), then protocol v3 is chosen. If the nodes
    # don't have a common protocol version, initialization fails.
    #
    # If this option is set, then the given version will be used for all connections, without any
    # negotiation or downgrading. If any of the contact points doesn't support it, that contact
    # point will be skipped.
    #
    # Once the protocol version is set, it can't change for the rest of the driver's lifetime; if
    # an incompatible node joins the cluster later, connection will fail and the driver will force
    # it down (i.e. never try to connect to it again).
    #
    # You can check the actual version at runtime with Cluster.getContext().getProtocolVersion().
    #
    # Required: no
    # Modifiable at runtime: no
    # Overridable in a profile: no
    // version = V4

    # The name of the algorithm used to compress protocol frames.
    #
    # The possible values are:
    # - lz4: requires net.jpountz.lz4:lz4 in the classpath.
    # - snappy: requires org.xerial.snappy:snappy-java in the classpath.
    #
    # The driver depends on the compression libraries, but they are optional. Make sure you
    # redeclare an explicit dependency in your project. Refer to the driver's POM or manual for the
    # exact version.
    #
    # Required: no. If the option is absent, protocol frames are not compressed.
    # Modifiable at runtime: no
    # Overridable in a profile: no
    // compression = lz4

    # The maximum length of the frames supported by the driver. Beyond that limit, requests will
    # fail with an exception
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for connections created after the
    #   change.
    # Overridable in a profile: no
    max-frame-length = 256 MB
  }

  advanced.request {
    # Whether a warning is logged when a request (such as a CQL `USE ...`) changes the active
    # keyspace.
    # Switching keyspace at runtime is highly discouraged, because it is inherently unsafe (other
    # requests expecting the old keyspace might be running concurrently), and may cause statements
    # prepared before the change to fail.
    # It should only be done in very specific use cases where there is only a single client thread
    # executing synchronous queries (such as a cqlsh-like interpreter). In other cases, clients
    # should prefix table names in their queries instead.
    #
    # Note that CASSANDRA-10145 (scheduled for C* 4.0) will introduce a per-request keyspace option
    # as a workaround to this issue.
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for keyspace switches occurring after
    #   the change.
    # Overridable in a profile: no
    warn-if-set-keyspace = true

    # If tracing is enabled for a query, this controls how the trace is fetched.
    trace {
      # How many times the driver will attempt to fetch the query if it is not ready yet.
      #
      # Required: yes
      # Modifiable at runtime: yes, the new value will be used for traces fetched after the change.
      # Overridable in a profile: yes
      attempts = 5

      # The interval between each attempt.
      #
      # Required: yes
      # Modifiable at runtime: yes, the new value will be used for traces fetched after the change.
      # Overridable in a profile: yes
      interval = 3 milliseconds

      # The consistency level to use for trace queries.
      # Note that the default replication strategy for the system_traces keyspace is SimpleStrategy
      # with RF=2, therefore LOCAL_ONE might not work if the local DC has no replicas for a given
      # trace id.
      #
      # Required: yes
      # Modifiable at runtime: yes, the new value will be used for traces fetched after the change.
      # Overridable in a profile: yes
      consistency = ONE
    }

    # Whether logging of server warnings generated during query execution should be disabled by the
    # driver. All server generated warnings will be available programmatically via the ExecutionInfo
    # object on the executed statement's ResultSet. If set to "false", this will prevent the driver
    # from logging these warnings.
    #
    # NOTE: The log formatting for these warning messages will reuse the options defined for
    # advanced.request-tracker.
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for query warnings received after the change.
    # Overridable in a profile: yes
    log-warnings = true
  }

  advanced.metrics {
    # The session-level metrics (all disabled by default).
    #
    # Required: yes
    # Modifiable at runtime: no
    # Overridable in a profile: no
    session {
      enabled = [
        # The number and rate of bytes sent for the entire session (exposed as a Meter).
        // bytes-sent,

        # The number and rate of bytes received for the entire session (exposed as a Meter).
        // bytes-received

        # The number of nodes to which the driver has at least one active connection (exposed as a
        # Gauge<Integer>).
        // connected-nodes,

        # The throughput and latency percentiles of CQL requests (exposed as a Timer).
        #
        # This corresponds to the overall duration of the session.execute() call, including any
        # retry.
        // cql-requests,

        # The number of CQL requests that timed out -- that is, the session.execute() call failed
        # with a DriverTimeoutException (exposed as a Counter).
        // cql-client-timeouts,

        # The size of the driver-side cache of CQL prepared statements.
        #
        # The cache uses weak values eviction, so this represents the number of PreparedStatement
        # instances that your application has created, and is still holding a reference to. Note
        # that the returned value is approximate.
        // cql-prepared-cache-size,

        # How long requests are being throttled (exposed as a Timer).
        #
        # This is the time between the start of the session.execute() call, and the moment when
        # the throttler allows the request to proceed.
        // throttling.delay,

        # The size of the throttling queue (exposed as a Gauge<Integer>).
        #
        # This is the number of requests that the throttler is currently delaying in order to
        # preserve its SLA. This metric only works with the built-in concurrency- and rate-based
        # throttlers; in other cases, it will always be 0.
        // throttling.queue-size,

        # The number of times a request was rejected with a RequestThrottlingException (exposed as
        # a Counter)
        // throttling.errors,
      ]

      # Extra configuration (for the metrics that need it)

      # Required: if the 'cql-requests' metric is enabled
      # Modifiable at runtime: no
      # Overridable in a profile: no
      cql-requests {
        # The largest latency that we expect to record.
        #
        # This should be slightly higher than request.timeout (in theory, readings can't be higher
        # than the timeout, but there might be a small overhead due to internal scheduling).
        #
        # This is used to scale internal data structures. If a higher recording is encountered at
        # runtime, it is discarded and a warning is logged.
        highest-latency = 3 seconds

        # The number of significant decimal digits to which internal structures will maintain
        # value resolution and separation (for example, 3 means that recordings up to 1 second
        # will be recorded with a resolution of 1 millisecond or better).
        #
        # This must be between 0 and 5. If the value is out of range, it defaults to 3 and a
        # warning is logged.
        significant-digits = 3

        # The interval at which percentile data is refreshed.
        #
        # The driver records latency data in a "live" histogram, and serves results from a cached
        # snapshot. Each time the snapshot gets older than the interval, the two are switched.
        # Note that this switch happens upon fetching the metrics, so if you never fetch the
        # recording interval might grow higher (that shouldn't be an issue in a production
        # environment because you would typically have a metrics reporter that exports to a
        # monitoring tool at a regular interval).
        #
        # In practice, this means that if you set this to 5 minutes, you're looking at data from a
        # 5-minute interval in the past, that is at most 5 minutes old. If you fetch the metrics
        # at a faster pace, you will observe the same data for 5 minutes until the interval
        # expires.
        #
        # Note that this does not apply to the total count and rates (those are updated in real
        # time).
        refresh-interval = 5 minutes
      }

      # Required: if the 'throttling.delay' metric is enabled
      # Modifiable at runtime: no
      # Overridable in a profile: no
      throttling.delay {
        highest-latency = 3 seconds
        significant-digits = 3
        refresh-interval = 5 minutes
      }
    }
    # The node-level metrics (all disabled by default).
    #
    # Required: yes
    # Modifiable at runtime: no
    # Overridable in a profile: no
    node {
      enabled = [
        # The number of connections open to this node for regular requests (exposed as a
        # Gauge<Integer>).
        #
        # This includes the control connection (which uses at most one extra connection to a
        # random node in the cluster).
        // pool.open-connections,

        # The number of stream ids available on the connections to this node (exposed as a
        # Gauge<Integer>).
        #
        # Stream ids are used to multiplex requests on each connection, so this is an indication
        # of how many more requests the node could handle concurrently before becoming saturated
        # (note that this is a driver-side only consideration, there might be other limitations on
        # the server that prevent reaching that theoretical limit).
        // pool.available-streams,

        # The number of requests currently executing on the connections to this node (exposed as a
        # Gauge<Integer>). This includes orphaned streams.
        // pool.in-flight,

        # The number of "orphaned" stream ids on the connections to this node (exposed as a
        # Gauge<Integer>).
        #
        # See the description of the connection.max-orphan-requests option for more details.
        // pool.orphaned-streams,

        # The number and rate of bytes sent to this node (exposed as a Meter).
        // bytes-sent,

        # The number and rate of bytes received from this node (exposed as a Meter).
        // bytes-received,

        # The throughput and latency percentiles of individual CQL messages sent to this node as
        # part of an overall request (exposed as a Timer).
        #
        # Note that this does not necessarily correspond to the overall duration of the
        # session.execute() call, since the driver might query multiple nodes because of retries
        # and speculative executions. Therefore a single "request" (as seen from a client of the
        # driver) can be composed of more than one of the "messages" measured by this metric.
        #
        # Therefore this metric is intended as an insight into the performance of this particular
        # node. For statistics on overall request completion, use the session-level cql-requests.
        // cql-messages,

        # The number of times the driver failed to send a request to this node (exposed as a
        # Counter).
        #
        # In those case we know the request didn't even reach the coordinator, so they are retried
        # on the next node automatically (without going through the retry policy).
        // errors.request.unsent,

        # The number of times a request was aborted before the driver even received a response
        # from this node (exposed as a Counter).
        #
        # This can happen in two cases: if the connection was closed due to an external event
        # (such as a network error or heartbeat failure); or if there was an unexpected error
        # while decoding the response (this can only be a driver bug).
        // errors.request.aborted,

        # The number of times this node replied with a WRITE_TIMEOUT error (exposed as a Counter).
        #
        # Whether this error is rethrown directly to the client, rethrown or ignored is determined
        # by the RetryPolicy.
        // errors.request.write-timeouts,

        # The number of times this node replied with a READ_TIMEOUT error (exposed as a Counter).
        #
        # Whether this error is rethrown directly to the client, rethrown or ignored is determined
        # by the RetryPolicy.
        // errors.request.read-timeouts,

        # The number of times this node replied with an UNAVAILABLE error (exposed as a Counter).
        #
        # Whether this error is rethrown directly to the client, rethrown or ignored is determined
        # by the RetryPolicy.
        // errors.request.unavailables,

        # The number of times this node replied with an error that doesn't fall under other
        # 'errors.*' metrics (exposed as a Counter).
        // errors.request.others,

        # The total number of errors on this node that caused the RetryPolicy to trigger a retry
        # (exposed as a Counter).
        #
        # This is a sum of all the other retries.* metrics.
        // retries.total,

        # The number of errors on this node that caused the RetryPolicy to trigger a retry, broken
        # down by error type (exposed as Counters).
        // retries.aborted,
        // retries.read-timeout,
        // retries.write-timeout,
        // retries.unavailable,
        // retries.other,

        # The total number of errors on this node that were ignored by the RetryPolicy (exposed as
        # a Counter).
        #
        # This is a sum of all the other ignores.* metrics.
        // ignores.total,

        # The number of errors on this node that were ignored by the RetryPolicy, broken down by
        # error type (exposed as Counters).
        // ignores.aborted,
        // ignores.read-timeout,
        // ignores.write-timeout,
        // ignores.unavailable,
        // ignores.other,

        # The number of speculative executions triggered by a slow response from this node
        # (exposed as a Counter).
        // speculative-executions,

        # The number of errors encountered while trying to establish a connection to this node
        # (exposed as a Counter).
        #
        # Connection errors are not a fatal issue for the driver, failed connections will be
        # retried periodically according to the reconnection policy. You can choose whether or not
        # to log those errors at WARN level with the connection.warn-on-init-error option.
        #
        # Authentication errors are not included in this counter, they are tracked separately in
        # errors.connection.auth.
        // errors.connection.init,

        # The number of authentication errors encountered while trying to establish a connection
        # to this node (exposed as a Counter).
        # Authentication errors are also logged at WARN level.
        // errors.connection.auth,
      ]

      # See cql-requests in the `session` section
      #
      # Required: if the 'cql-messages' metric is enabled
      # Modifiable at runtime: no
      # Overridable in a profile: no
      cql-messages {
        highest-latency = 3 seconds
        significant-digits = 3
        refresh-interval = 5 minutes
      }
    }
  }

  advanced.socket {
    # Whether or not to disable the Nagle algorithm.
    #
    # By default, this option is set to true (Nagle disabled), because the driver has its own
    # internal message coalescing algorithm.
    #
    # See java.net.StandardSocketOptions.TCP_NODELAY.
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for connections created after the
    #   change.
    # Overridable in a profile: no
    tcp-no-delay = true

    # All other socket options are unset by default. The actual value depends on the underlying
    # Netty transport:
    # - NIO uses the defaults from java.net.Socket (refer to the javadocs of
    #   java.net.StandardSocketOptions for each option).
    # - Epoll delegates to the underlying file descriptor, which uses the O/S defaults.

    # Whether or not to enable TCP keep-alive probes.
    #
    # See java.net.StandardSocketOptions.SO_KEEPALIVE.
    #
    # Required: no
    # Modifiable at runtime: yes, the new value will be used for connections created after the
    #   change.
    # Overridable in a profile: no
    //keep-alive = false

    # Whether or not to allow address reuse.
    #
    # See java.net.StandardSocketOptions.SO_REUSEADDR.
    #
    # Required: no
    # Modifiable at runtime: yes, the new value will be used for connections created after the
    #   change.
    # Overridable in a profile: no
    //reuse-address = true

    # Sets the linger interval.
    #
    # If the value is zero or greater, then it represents a timeout value, in seconds;
    # if the value is negative, it means that this option is disabled.
    #
    # See java.net.StandardSocketOptions.SO_LINGER.
    #
    # Required: no
    # Modifiable at runtime: yes, the new value will be used for connections created after the
    #   change.
    # Overridable in a profile: no
    //linger-interval = 0

    # Sets a hint to the size of the underlying buffers for incoming network I/O.
    #
    # See java.net.StandardSocketOptions.SO_RCVBUF.
    #
    # Required: no
    # Modifiable at runtime: yes, the new value will be used for connections created after the
    #   change.
    # Overridable in a profile: no
    //receive-buffer-size = 65535

    # Sets a hint to the size of the underlying buffers for outgoing network I/O.
    #
    # See java.net.StandardSocketOptions.SO_SNDBUF.
    #
    # Required: no
    # Modifiable at runtime: yes, the new value will be used for connections created after the
    #   change.
    # Overridable in a profile: no
    //send-buffer-size = 65535
  }

  advanced.heartbeat {
    # The heartbeat interval. If a connection stays idle for that duration (no reads), the driver
    # sends a dummy message on it to make sure it's still alive. If not, the connection is trashed
    # and replaced.
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for connections created after the
    #   change.
    # Overridable in a profile: no
    interval = 30 seconds

    # How long the driver waits for the response to a heartbeat. If this timeout fires, the
    # heartbeat is considered failed.
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for connections created after the
    #   change.
    # Overridable in a profile: no
    timeout = ${datastax-java-driver.advanced.connection.init-query-timeout}
  }

  advanced.metadata {
    # Topology events are external signals that inform the driver of the state of Cassandra nodes
    # (by default, they correspond to gossip events received on the control connection).
    # The debouncer helps smoothen out oscillations if conflicting events are sent out in short
    # bursts.
    # Debouncing may be disabled by setting the window to 0 or max-events to 1 (this is not
    # recommended).
    topology-event-debouncer {
      # How long the driver waits to propagate an event. If another event is received within that
      # time, the window is reset and a batch of accumulated events will be delivered.
      #
      # Required: yes
      # Modifiable at runtime: no
      # Overridable in a profile: no
      window = 1 second

      # The maximum number of events that can accumulate. If this count is reached, the events are
      # delivered immediately and the time window is reset. This avoids holding events indefinitely
      # if the window keeps getting reset.
      #
      # Required: yes
      # Modifiable at runtime: no
      # Overridable in a profile: no
      max-events = 20
    }

    # Options relating to schema metadata (Cluster.getMetadata.getKeyspaces).
    # This metadata is exposed by the driver for informational purposes, and is also necessary for
    # token-aware routing.
    schema {
      # Whether schema metadata is enabled.
      # If this is false, the schema will remain empty, or to the last known value.
      #
      # Required: yes
      # Modifiable at runtime: yes, the new value will be used for refreshes issued after the
      #   change. It can also be overridden programmatically via Cluster.setSchemaMetadataEnabled.
      # Overridable in a profile: no
      enabled = true

      # The list of keyspaces for which schema and token metadata should be maintained. If this
      # property is absent or empty, all existing keyspaces are processed.
      #
      # Required: no
      # Modifiable at runtime: yes, the new value will be used for refreshes issued after the
      #   change.
      # Overridable in a profile: no
      // refreshed-keyspaces = [ "ks1", "ks2" ]

      # The timeout for the requests to the schema tables.
      #
      # Required: yes
      # Modifiable at runtime: yes, the new value will be used for refreshes issued after the
      #   change.
      # Overridable in a profile: no
      request-timeout = ${datastax-java-driver.basic.request.timeout}

      # The page size for the requests to the schema tables.
      #
      # Required: yes
      # Modifiable at runtime: yes, the new value will be used for refreshes issued after the
      #   change.
      # Overridable in a profile: no
      request-page-size = ${datastax-java-driver.basic.request.page-size}

      # Protects against bursts of schema updates (for example when a client issues a sequence of
      # DDL queries), by coalescing them into a single update.
      # Debouncing may be disabled by setting the window to 0 or max-events to 1 (this is highly
      # discouraged for schema refreshes).
      debouncer {
        # How long the driver waits to apply a refresh. If another refresh is requested within that
        # time, the window is reset and a single refresh will be triggered when it ends.
        #
        # Required: yes
        # Modifiable at runtime: no
        # Overridable in a profile: no
        window = 1 second

        # The maximum number of refreshes that can accumulate. If this count is reached, a refresh
        # is done immediately and the window is reset.
        #
        # Required: yes
        # Modifiable at runtime: no
        # Overridable in a profile: no
        max-events = 20
      }
    }

    # Whether token metadata (Cluster.getMetadata.getTokenMap) is enabled.
    # This metadata is exposed by the driver for informational purposes, and is also necessary for
    # token-aware routing.
    # If this is false, it will remain empty, or to the last known value. Note that its computation
    # requires information about the schema; therefore if schema metadata is disabled or filtered to
    # a subset of keyspaces, the token map will be incomplete, regardless of the value of this
    # property.
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for refreshes issued after the change.
    # Overridable in a profile: no
    token-map.enabled = true
  }

  advanced.control-connection {
    # How long the driver waits for responses to control queries (e.g. fetching the list of nodes,
    # refreshing the schema).
    #
    # Required: yes
    # Modifiable at runtime: no
    # Overridable in a profile: no
    timeout = ${datastax-java-driver.advanced.connection.init-query-timeout}

    # Due to the distributed nature of Cassandra, schema changes made on one node might not be
    # immediately visible to others. Under certain circumstances, the driver waits until all nodes
    # agree on a common schema version (namely: before a schema refresh, before repreparing all
    # queries on a newly up node, and before completing a successful schema-altering query). To do
    # so, it queries system tables to find out the schema version of all nodes that are currently
    # UP. If all the versions match, the check succeeds, otherwise it is retried periodically, until
    # a given timeout.
    #
    # A schema agreement failure is not fatal, but it might produce unexpected results (for example,
    # getting an "unconfigured table" error for a table that you created right before, just because
    # the two queries went to different coordinators).
    #
    # Note that schema agreement never succeeds in a mixed-version cluster (it would be challenging
    # because the way the schema version is computed varies across server versions); the assumption
    # is that schema updates are unlikely to happen during a rolling upgrade anyway.
    schema-agreement {
      # The interval between each attempt.
      # Required: yes
      # Modifiable at runtime: yes, the new value will be used for checks issued after the change.
      # Overridable in a profile: no
      interval = 200 milliseconds

      # The timeout after which schema agreement fails.
      # If this is set to 0, schema agreement is skipped and will always fail.
      #
      # Required: yes
      # Modifiable at runtime: yes, the new value will be used for checks issued after the change.
      # Overridable in a profile: no
      timeout = 10 seconds

      # Whether to log a warning if schema agreement fails.
      # You might want to change this if you've set the timeout to 0.
      #
      # Required: yes
      # Modifiable at runtime: yes, the new value will be used for checks issued after the change.
      # Overridable in a profile: no
      warn-on-failure = true
    }
  }

  advanced.prepared-statements {
    # Whether `Session.prepare` calls should be sent to all nodes in the cluster.
    #
    # A request to prepare is handled in two steps:
    # 1) send to a single node first (to rule out simple errors like malformed queries).
    # 2) if step 1 succeeds, re-send to all other active nodes (i.e. not ignored by the load
    # balancing policy).
    # This option controls whether step 2 is executed.
    #
    # The reason why you might want to disable it is to optimize network usage if you have a large
    # number of clients preparing the same set of statements at startup. If your load balancing
    # policy distributes queries randomly, each client will pick a different host to prepare its
    # statements, and on the whole each host has a good chance of having been hit by at least one
    # client for each statement.
    # On the other hand, if that assumption turns out to be wrong and one host hasn't prepared a
    # given statement, it needs to be re-prepared on the fly the first time it gets executed; this
    # causes a performance penalty (one extra roundtrip to resend the query to prepare, and another
    # to retry the execution).
    #
    # Required: yes
    # Modifiable at runtime: yes, the new value will be used for prepares issued after the change.
    # Overridable in a profile: yes
    prepare-on-all-nodes = true

    # How the driver replicates prepared statements on a node that just came back up or joined the
    # cluster.
    reprepare-on-up {
      # Whether the driver tries to prepare on new nodes at all.
      #
      # The reason why you might want to disable it is to optimize reconnection time when you
      # believe nodes often get marked down because of temporary network issues, rather than the
      # node really crashing. In that case, the node still has prepared statements in its cache when
      # the driver reconnects, so re-preparing is redundant.
      #
      # On the other hand, if that assumption turns out to be wrong and the node had really
      # restarted, its prepared statement cache is empty (before CASSANDRA-8831), and statements
      # need to be re-prepared on the fly the first time they get executed; this causes a
      # performance penalty (one extra roundtrip to resend the query to prepare, and another to
      # retry the execution).
      #
      # Required: yes
      # Modifiable at runtime: yes, the new value will be used for nodes that come back up after the
      #   change.
      # Overridable in a profile: no
      enabled = true

      # Whether to check `system.prepared_statements` on the target node before repreparing.
      #
      # This table exists since CASSANDRA-8831 (merged in 3.10). It stores the statements already
      # prepared on the node, and preserves them across restarts.
      #
      # Checking the table first avoids repreparing unnecessarily, but the cost of the query is not
      # always worth the improvement, especially if the number of statements is low.
      #
      # If the table does not exist, or the query fails for any other reason, the error is ignored
      # and the driver proceeds to reprepare statements according to the other parameters.
      #
      # Required: yes
      # Modifiable at runtime: yes, the new value will be used for nodes that come back up after the
      #   change.
      # Overridable in a profile: no
      check-system-table = false

      # The maximum number of statements that should be reprepared. 0 or a negative value means no
      # limit.
      #
      # Required: yes
      # Modifiable at runtime: yes, the new value will be used for nodes that come back up after the
      #   change.
      # Overridable in a profile: no
      max-statements = 0

      # The maximum number of concurrent requests when repreparing.
      #
      # Required: yes
      # Modifiable at runtime: yes, the new value will be used for nodes that come back up after the
      #   change.
      # Overridable in a profile: no
      max-parallelism = 100

      # The request timeout. This applies both to querying the system.prepared_statements table (if
      # relevant), and the prepare requests themselves.
      #
      # Required: yes
      # Modifiable at runtime: yes, the new value will be used for nodes that come back up after the
      #   change.
      # Overridable in a profile: no
      timeout = ${datastax-java-driver.advanced.connection.init-query-timeout}
    }
  }

  # Options related to the Netty event loop groups used internally by the driver.
  advanced.netty {
    # The event loop group used for I/O operations (reading and writing to Cassandra nodes).
    # By default, threads in this group are named after the session name, "-io-" and an incrementing
    # counter, for example "s0-io-0".
    io-group {
      # The number of threads.
      # If this is set to 0, the driver will use `Runtime.getRuntime().availableProcessors() * 2`.
      #
      # Required: yes
      # Modifiable at runtime: no
      # Overridable in a profile: no
      size = 0

      # The options to shut down the event loop group gracefully when the driver closes. If a task
      # gets submitted during the quiet period, it is accepted and the quiet period starts over.
      # The timeout limits the overall shutdown time.
      #
      # Required: yes
      # Modifiable at runtime: no
      # Overridable in a profile: no
      shutdown {quiet-period = 2, timeout = 15, unit = SECONDS}
    }
    # The event loop group used for admin tasks not related to request I/O (handle cluster events,
    # refresh metadata, schedule reconnections, etc.)
    # By default, threads in this group are named after the session name, "-admin-" and an
    # incrementing counter, for example "s0-admin-0".
    admin-group {
      size = 2

      shutdown {quiet-period = 2, timeout = 15, unit = SECONDS}
    }
    # The timer used for scheduling request timeouts and speculative executions
    # By default, this thread is named after the session name and "-timer-0", for example
    # "s0-timer-0".
    timer {
      # The timer tick duration.
      # This is how frequent the timer should wake up to check for timed-out tasks or speculative
      # executions. Lower resolution (i.e. longer durations) will leave more CPU cycles for running
      # I/O operations at the cost of precision of exactly when a request timeout will expire or a
      # speculative execution will run. Higher resolution (i.e. shorter durations) will result in
      # more precise request timeouts and speculative execution scheduling, but at the cost of CPU
      # cycles taken from I/O operations, which could lead to lower overall I/O throughput.
      #
      # The default value is 100 milliseconds, which is a comfortable value for most use cases.
      # However if you are using more agressive timeouts or speculative execution delays, then you
      # should lower the timer tick duration as well, so that its value is always equal to or lesser
      # than the timeout duration and/or speculative execution delay you intend to use.
      #
      # Note for Windows users: avoid setting this to aggressive values, that is, anything under 100
      # milliseconds; doing so is known to cause extreme CPU usage. Also, the tick duration must be
      # a multiple of 10 under Windows; if that is not the case, it will be automatically rounded
      # down to the nearest multiple of 10 (e.g. 99 milliseconds will be rounded down to 90
      # milliseconds).
      #
      # Required: yes
      # Modifiable at runtime: no
      # Overridable in a profile: no
      tick-duration = 100 milliseconds

      # Number of ticks in a Timer wheel. The underlying implementation uses Netty's
      # HashedWheelTimer, which uses hashes to arrange the timeouts. This effectively controls the
      # size of the timer wheel.
      #
      # Required: yes
      # Modifiable at runtime: no
      # Overridable in a profile: no
      ticks-per-wheel = 2048
    }
  }

  # The component that coalesces writes on the connections.
  # This is exposed mainly to facilitate tuning during development. You shouldn't have to adjust
  # this.
  advanced.coalescer {
    # How many times the coalescer is allowed to reschedule itself when it did no work.
    #
    # Required: yes
    # Modifiable at runtime: no
    # Overridable in a profile: no
    max-runs-with-no-work = 5

    # The reschedule interval.
    #
    # Required: yes
    # Modifiable at runtime: no
    # Overridable in a profile: no
    reschedule-interval = 10 microseconds
  }

  profiles {
    # This is where your custom profiles go, for example:
    # olap {
    #   basic.request.timeout = 5 seconds
    # }
  }
}