SQL Driver: Cassandra

Driver name cassandra.

Driver for Apache Cassandra CQL server.

To compile support for this driver, you need to have DataStax C/C++ driver and headers installed.

Supported Options

`connect_timeout`

Default: 5s
Values: time (milliseconds)

Connection timeout.

`dbname`

Alias for keyspace.

`debug_queries`

Default: no
Values: boolean

Whether to log CQL queries.

Note

This setting behaves differently than other boolean settings. The feature is enabled by presence of the keyword in connect string, so to disable this feature, you must remove the keyword completely.

`delete_consistency`

Default: local-quorum
Values: consistency

Write consistency when deleting from the database.

`delete_fallback_consistency`

Default: local-quorum
Values: consistency

Write consistency when deleting from the database fails with primary consistency.

`execution_retry_interval`

Default: 0
Values: time (milliseconds)
See Also: https://docs.datastax.com/en/developer/java-driver/latest/manual/core/speculative_execution/index.html

If the driver supports speculative execution policy, configures constant speculative execution policy.

`execution_retry_times`

Default: 0
Values: time (milliseconds)
See Also: https://docs.datastax.com/en/developer/java-driver/latest/manual/core/speculative_execution/index.html

If the driver supports speculative execution policy, configures constant speculative execution policy.

`heartbeat_interval`

Default: 5s
Values: time

How often to send keepalive packets to cassandra nodes.

`host`

Values: string

Host or IP address to connect. Can appear multiple times.

`idle_timeout`

Default: 0
Values: time (milliseconds)

How long to idle before disconnecting.

`keyspace`

Values: string

Specifies the keyspace name to use.

`latency_aware_routing`

Default: no
Values: boolean

When turned on, latency-aware routing tracks the latency of queries to avoid sending new queries to poorly performing Cassandra nodes.

Note

The feature is enabled by presence of the keyword in connect string, so to disable this feature, you must remove the keyword completely.

`log_level`

Default: warn
Values: critical, error, warn, info, debug, trace

Driver log level.

`log_retries`

Default: no
Values: boolean
Added: 2.4.0

Whether to log about failed requests that are retried (which may or may not succeed after the retry).

Note

This setting behaves differently than other boolean settings.

The feature is enabled by presence of the keyword in connect string, so to disable this feature, you must remove the keyword completely.

`metrics`

Values: string
See Also: Cassandra Metrics

Path where to write JSON metrics.

`num_threads`

Default: <driver dependent>
Values: unsigned integer

Set number of IO threads to handle query requests.

`page_size`

Default: -1
Values: unsigned integer

When a query returns many rows, it can be sometimes inefficient to return them as a single response message. Instead, the driver can break the results into pages which get returned as they are needed.

This setting controls the size of each page.

Set to -1 to disable.

`password`

Values: string

Password for authentication.

`port`

Default: 9042
Values: unsigned integer

CQL port to use.

`read_consistency`

Default: local-quorum
Values: consistency

Read consistency.

`read_fallback_consistency`

Default: local-quorum
Values: consistency

Read consistency if primary consistency fails.

`request_timeout`

Default: 60s
Values: time (milliseconds)

How long to wait for a query to finish.

`ssl_ca`

Values: string

Path to SSL certificate authority file to use to validate peer certificate.

`ssl_cert_file`

Values: string

Path to a certificate file to use for authenticating against the remote server.

`ssl_private_key_file`

Values: string

Path to private key matching ssl_cert_file to use for authenticating against the remote server.

`ssl_verify`

Default: none
Values: none, cert, cert-ip

Configure the peer certificate validation method.

Options:

Method	Description
`none`	Disables validation.
`cert`	Validate that the certificate is valid.
`cert-ip`	Validate that the certificate is valid and has Common Name or Subject Alternate Name for the IP address.

`user`

Values: string

Username for authentication.

`version`

Default: <depends on driver version>
Values: 3, 4, 5

Cassandra protocol version to use. It is good idea to specify this to avoid warnings about version handshake if the driver supports a higher protocol version than the server.

Note

If you want to use server-side prepared statements, you need to use at least 4.

`warn_timeout`

Default: 5s
Values: time (milliseconds)

Emit warning if query takes longer than this.

`write_consistency`

Default: local-quorum
Values: consistency

Write consistency when updating or inserting to the database.

`write_fallback_consistency`

Default: local-quorum
Values: consistency

Write consistency when updating or inserting to the database fails with primary consistency.

Cassandra Consistency

Consistency levels in Cassandra can be configured to manage availability versus data accuracy.

Read Consistency

`any`

Note

Not supported for reads.

`local-serial`

Allows reading the current (and possibly uncommitted) state of data without proposing a new addition or update.

If a SERIAL read finds an uncommitted transaction in progress, it will commit the transaction as part of the read.

Local serial is confined to datacenter.

`serial`

Allows reading the current (and possibly uncommitted) state of data without proposing a new addition or update.

If a SERIAL read finds an uncommitted transaction in progress, it will commit the transaction as part of the read.

`one`

Returns a response from the closest replica, as determined by the snitch.

`two`

Returns the most recent data from two of the closest replicas.

`three`

Returns the most recent data from three of the closest replicas.

`local-quorum`

Returns the record after a quorum of replicas in the current datacenter as the coordinator has reported.

`quorum`

Returns the record after a quorum of replicas from all datacenters has responded.

`each-quorum`

Note

Not supported for reads.

`all`

Returns the record after all replicas have responded. The read operation will fail if a replica does not respond.

Write/Delete Consistency

`any`

At least one node must succeed in the operation.

`local-serial`

Note

Not supported for writes.

`serial`

Note

Not supported for writes.

`one`

Operation must be at least in commit log and one memory table of one replica.

`two`

Operation must be at least in commit log and one memory table of two replicas.

`three`

Operation must be at least in commit log and one memory table of three replicas.

`local-quorum`

A write must be written to the commit log and memory table on a quorum of replica nodes in the same datacenter as the coordinator.

`quorum`

A write must be written to the commit log and memory table on a quorum of replica nodes across all datacenters.

`each-quorum`

A write must be written to the commit log and memory table on a quorum of replica nodes in each datacenter.

`all`

A write must be written to the commit log and memtable on all replica nodes in the cluster for that partition.

Cassandra Metrics

This describes the format of the JSON output produced when the metrics configuration option is activated.

Source: https://docs.datastax.com/en/developer/cpp-driver/latest/api/struct.CassMetrics/index.html

Details

json

{
    "Requests": {
        # Minimum in microseconds
        "min": [Number: integer],
        # Maximum in microseconds
        "max": [Number: integer],
        # Mean in microseconds
        "mean": [Number: integer],
        # Standard deviation in microseconds
        "stddev": [Number: integer],
        # Median in microseconds
        "median": [Number: integer],
        # 75th percentile in microseconds
        "percentile_75th": [Number: integer],
        # 95th percentile in microseconds
        "percentile_95th": [Number: integer],
        # 98th percentile in microseconds
        "percentile_98th": [Number: integer],
        # 99th percentile in microseconds
        "percentile_99th": [Number: integer],
        # 99.9th percentile in microseconds
        "percentile_999th": [Number: integer],
        # Mean rate in requests per second
        "mean_rate": [Number: fraction],
        # 1 minute rate in requests per second
        "one_minute_rate": [Number: fraction],
        # 5 minute rate in requests per second
        "five_minute_rate": [Number: fraction],
        # 15 minute rate in requests per second
        "fifteen_minute_rate": [Number: fraction]
    },
    "stats": {
        # The total number of connections
        "total_connections": [Number: integer],
        # The number of connections available to take requests
        "available_connections": [Number: integer],
        # Occurrences when requests exceeded a pool's water mark
        "exceeded_pending_requests_water_mark": [Number: integer],
        # Occurrences when number of bytes exceeded a connection's water mark
        "exceeded_write_bytes_water_mark": [Number: integer]
    },
    "queries": {
        # Number of queries sent to Cassandra
        "sent": [Number: integer],
        # Number of successful responses
        "recv_ok": [Number: integer],
        # Number of requests that couldn’t be sent, because the local
        # Cassandra driver’s queue was full.
        "recv_err_queue_full": [Number: integer],
        # Number of requests that didn’t succeed because the Cassandra
        # driver couldn’t connect to the server.
        "recv_err_no_hosts": [Number: integer],
        # Number of requests that didn’t succeed because the Cassandra
        # driver timed out while waiting for response from server.
        "recv_err_client_timeout": [Number: integer],
        # Number of requests that didn’t succeed because the Cassandra
        # server reported a timeout communicating with other nodes.
        "recv_err_server_timeout": [Number: integer],
        # Number of requests which couldn’t succeed, because not enough
        # Cassandra nodes were available for the consistency level.
        "recv_err_server_unavailable": [Number: integer]
        # Number of requests which couldn’t succeed for other reasons.
        "recv_err_other": [Number: integer]
    },
    "errors": {
        # Occurrences of a connection timeout
        "connection_timeouts": [Number: integer],
        # [No description provided]
         "pending_request_timeouts": [Number: integer],
        # Occurrences of requests that timed out waiting for a connection
        "request_timeouts": [Number: integer]
    }
}

Databases

Mechanisms

Formats

Extensions

SQL Driver: Cassandra ​

Supported Options ​

connect_timeout ​

dbname ​

debug_queries ​

delete_consistency ​

delete_fallback_consistency ​

execution_retry_interval ​

execution_retry_times ​

heartbeat_interval ​

host ​

idle_timeout ​

keyspace ​

latency_aware_routing ​

log_level ​

log_retries ​

metrics ​

num_threads ​

page_size ​

password ​

port ​

read_consistency ​

read_fallback_consistency ​

request_timeout ​

ssl_ca ​

ssl_cert_file ​

ssl_private_key_file ​

ssl_verify ​

user ​

version ​

warn_timeout ​

write_consistency ​

write_fallback_consistency ​

Cassandra Consistency ​

Read Consistency ​

any ​

local-serial ​

serial ​

one ​

two ​

three ​

local-quorum ​

quorum ​

each-quorum ​

all ​

Write/Delete Consistency ​

any ​

local-serial ​

serial ​

one ​

two ​

three ​

local-quorum ​

quorum ​

each-quorum ​

all ​

Cassandra Metrics ​

SQL Driver: Cassandra

Supported Options

`connect_timeout`

`dbname`

`debug_queries`

`delete_consistency`

`delete_fallback_consistency`

`execution_retry_interval`

`execution_retry_times`

`heartbeat_interval`

`host`

`idle_timeout`

`keyspace`

`latency_aware_routing`

`log_level`

`log_retries`

`metrics`

`num_threads`

`page_size`

`password`

`port`

`read_consistency`

`read_fallback_consistency`

`request_timeout`

`ssl_ca`

`ssl_cert_file`

`ssl_private_key_file`

`ssl_verify`

`user`

`version`

`warn_timeout`

`write_consistency`

`write_fallback_consistency`

Cassandra Consistency

Read Consistency

`any`

`local-serial`

`serial`

`one`

`two`

`three`

`local-quorum`

`quorum`

`each-quorum`

`all`

Write/Delete Consistency

`any`

`local-serial`

`serial`

`one`

`two`

`three`

`local-quorum`

`quorum`

`each-quorum`

`all`

Cassandra Metrics