Hackage :: [Package]

cql-io: Cassandra CQL client.

[ database, library, mpl ] [ Propose Tags ] [ Report a vulnerability ]

CQL Cassandra driver supporting native protocol versions 3 and 4.

This library uses the cql library which implements Cassandra's CQL protocol and complements it with the neccessary I/O operations. The feature-set includes:

  • Node discovery. The driver discovers nodes automatically from a small set of bootstrap nodes.

  • Customisable load-balancing policies. In addition to pre-built LB policies such as round-robin, users of this library can provide their own policies if desired. The policy API is rich enough to support token aware routing policies.

  • Support for connection streams. Requests can be multiplexed over a few connections.

  • Customisable retry settings. Support for default retry settings as well as local overrides per query.

  • Prepared queries. Prepared queries are an optimisation which parse and prepare a query only once on Cassandra nodes but execute it many times with different concrete values.

  • TLS support. Client to node communication can optionally use transport layer security (using HsOpenSSL).

[Skip to Readme]

library cql-io

Modules

[Last Documentation]

  • Database
    • CQL
      • Database.CQL.IO
        • Database.CQL.IO.Hexdump

library cql-io:cql-io-lib

Modules

[Last Documentation]

  • Database
    • CQL
      • IO
        • Database.CQL.IO.Batch
        • Database.CQL.IO.Client
        • Cluster
          • Database.CQL.IO.Cluster.Discovery
          • Database.CQL.IO.Cluster.Host
          • Database.CQL.IO.Cluster.Policies
        • Database.CQL.IO.Connection
          • Database.CQL.IO.Connection.Settings
          • Database.CQL.IO.Connection.Socket
        • Database.CQL.IO.Exception
        • Database.CQL.IO.Hexdump
        • Database.CQL.IO.Jobs
        • Database.CQL.IO.Log
        • Database.CQL.IO.Pool
        • Database.CQL.IO.PrepQuery
        • Database.CQL.IO.Protocol
        • Database.CQL.IO.Replication
        • Database.CQL.IO.Settings
        • Database.CQL.IO.Signal
        • Database.CQL.IO.Sync
        • Database.CQL.IO.Tickets
        • Database.CQL.IO.Timeouts

Downloads

Versions [RSS] 0.9.6, 0.9.7, 0.10.1, 0.12.0, 0.12.1, 0.12.2, 0.13.0, 0.13.1, 0.13.2, 0.14.1, 0.14.2, 0.14.3, 0.14.4, 0.14.5, 0.15.2, 0.16.0, 1.0.0, 1.0.1, 1.0.1.1, 1.1.0, 1.1.1, 2.0.0
Change log CHANGELOG
Dependencies async (>=2.2 && <2.3), attoparsec (>=0.14 && <1), auto-update (>=0.1 && <0.3), base (>=4.9 && <5), bluefin (>=0.0.15 && <0.18), bytestring (>=0.10 && <0.13), containers (>=0.6.6 && <0.9), cql (>=4.1 && <4.2), cql-io, crypton (>=1.0 && <1.1), data-default-class (>=0.2 && <0.3), exceptions (>=0.4 && <0.11), hashable (>=1.2 && <1.6), HsOpenSSL (>=0.11 && <0.12), iproute (>=1.3 && <1.8), lens (>=4.4 && <5.4), mtl (>=2.1 && <2.4), mwc-random (>=0.13 && <0.16), network (>=2.4 && <3.3), persist (>=1.0 && <1.1), random-shuffle (>=0.0.4 && <0.1), retry (>=0.7 && <0.10), semigroups (>=0.15 && <0.21), semver (>=0.4.0.1 && <1), stm (>=2.5.1 && <2.6), text (>=0.11 && <2.2), time (>=1.4 && <1.16), transformers (>=0.6.0.2 && <0.7), unliftio-core (>=0.1.1 && <0.3), unordered-containers (>=0.2 && <0.3), uuid (>=1.2.6 && <1.4), vector (>=0.10 && <0.14) [details]
License MPL-2.0
Copyright (C) 2014-2016 Toralf Wittner, 2025 Kyle Butt
Author Toralf Wittner
Maintainer Kyle Butt <kyle@iteratee.net>
Category Database
Home page https://github.com/iteratee/cql-io
Bug tracker https://github.com/iteratee/cql-io/issues
Source repo head: git clone https://github.com/iteratee/cql-io
Uploaded by KyleButt at 2025-10-17T00:26:22Z
Distributions LTSHaskell:1.1.1
Reverse Dependencies 2 direct, 0 indirect [details]
Downloads 16072 total (73 in the last 30 days)
Rating 2.0 (votes: 1) [estimated by Bayesian average]
Your Rating
  • λ
  • λ
  • λ
Status Docs not available [build log]
All reported builds failed as of 2025-10-17 [all 2 reports]

Readme for cql-io-2.0.0

[back to package description]

CQL Cassandra driver

This library uses the cql library which implements Cassandra's CQL protocol and complements it with the neccessary I/O operations. The feature-set includes:

Node discovery

The driver discovers nodes automatically from a small set of bootstrap nodes.

Customisable load-balancing policies

In addition to pre-built LB policies such as round-robin, users of this library can provide their own policies if desired.

Support for connection streams

Requests can be multiplexed over a few connections.

Customisable retry settings

Support for default retry settings as well as local overrides per query.

Prepared queries

Prepared queries are an optimisation which parse and prepare a query only once on Cassandra nodes but execute it many times with different concrete values.

TLS support

Client to node communication can optionally use transport layer security (using HsOpenSSL).

Testing

The tests assume that a CQL cluster is available and running. The host should either be available at localhost, or the environment variable CASSANDRA_HOST. To spin up a single host for a simple test, you can do the following:

docker run --rm -ti --cpus 4 --memory 8G --name cql-io-cassandra \
  -p ::1:9042:9042 -v /tmp/cql-io-test-data:/var/lib/cassandra \
  --env MAX_HEAP_SIZE=1536M --env NEW_HEAP_SIZE=256M cassandra:5.0.5-jammy

License

See LICENSE.

Cassandra Logo License

Copyright © 2018 Apache Software Foundation

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at https://www.apache.org/licenses/LICENSE-2.0. Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.