The following matrix shows the versions of Go and Cassandra that are tested with the integration test suite as part of the CI build:
Go/Cassandra
2.1.x
2.2.x
3.x.x
1.17
yes
yes
yes
1.18
yes
yes
yes
Gocql has been tested in production against many different versions of Cassandra. Due to limits in our CI setup we only test against the latest 3 major releases, which coincide with the official support from the Apache project.
Sunsetting Model
In general, the gocql team will focus on supporting the current and previous versions of Go. gocql may still work with older versions of Go, but official support for these versions will have been sunset.
Installation
go get github.com/gocql/gocql
Features
Modern Cassandra client using the native transport
Automatic type conversions between Cassandra and Go
Support for all common types including sets, lists and maps
Custom types can implement a Marshaler and Unmarshaler interface
Strict type conversions without any loss of precision
Built-In support for UUIDs (version 1 and 4)
Support for logged, unlogged and counter batches
Cluster management
Automatic reconnect on connection failures with exponential falloff
Round robin distribution of queries to different hosts
Round robin distribution of queries to different connections on a host
Each connection can execute up to n concurrent queries (whereby n is the limit set by the protocol version the client chooses to use)
Optional automatic discovery of nodes
Policy based connection pool with token aware and round-robin policy implementations
Support for password authentication
Iteration over paged results with configurable page size
An API to access the schema metadata of a given keyspace
Performance
While the driver strives to be highly performant, there are cases where it is difficult to test and verify. The driver is built
with maintainability and code readability in mind first and then performance and features, as such every now and then performance
may degrade, if this occurs please report and issue and it will be looked at and remedied. The only time the driver copies data from
its read buffer is when it Unmarshal's data into supplied types.
Some tips for getting more performance from the driver:
Use the TokenAware policy
Use many goroutines when doing inserts, the driver is asynchronous but provides a synchronous API, it can execute many queries concurrently
Tune query page size
Reading data from the network to unmarshal will incur a large amount of allocations, this can adversely affect the garbage collector, tune GOGC
Close iterators after use to recycle byte buffers
Important Default Keyspace Changes
gocql no longer supports executing "use " statements to simplify the library. The user still has the
ability to define the default keyspace for connections but now the keyspace can only be defined before a
session is created. Queries can still access keyspaces by indicating the keyspace in the query:
There are various ways to bind application level data structures to CQL statements:
You can write the data binding by hand, as outlined in the Tweet example. This provides you with the greatest flexibility, but it does mean that you need to keep your application code in sync with your Cassandra schema.
You can dynamically marshal an entire query result into an []map[string]interface{} using the SliceMap() API. This returns a slice of row maps keyed by CQL column names. This method requires no special interaction with the gocql API, but it does require your application to be able to deal with a key value view of your data.
As a refinement on the SliceMap() API you can also call MapScan() which returns map[string]interface{} instances in a row by row fashion.
The Bind() API provides a client app with a low level mechanism to introspect query meta data and extract appropriate field values from application level data structures.
The gocqlx package is an idiomatic extension to gocql that provides usability features. With gocqlx you can bind the query parameters from maps and structs, use named query parameters (:identifier) and scan the query results into structs and slices. It comes with a fluent and flexible CQL query builder that supports full CQL spec, including BATCH statements and custom functions.
Building on top of the gocql driver, cqlr adds the ability to auto-bind a CQL iterator to a struct or to bind a struct to an INSERT statement.
Another external project that layers on top of gocql is cqlc which generates gocql compliant code from your Cassandra schema so that you can write type safe CQL statements in Go with a natural query syntax.
gocassa is an external project that layers on top of gocql to provide convenient query building and data binding.
gocqltable provides an ORM-style convenience layer to make CRUD operations with gocql easier.
Ecosystem
The following community maintained tools are known to integrate with gocql:
gocqlx is a gocql extension that automates data binding, adds named queries support, provides flexible query builders and plays well with gocql.
journey is a migration tool with Cassandra support.
cqlr adds the ability to auto-bind a CQL iterator to a struct or to bind a struct to an INSERT statement.
cqlc generates gocql compliant code from your Cassandra schema so that you can write type safe CQL statements in Go with a natural query syntax.
gocassa provides query building, adds data binding, and provides easy-to-use "recipe" tables for common query use-cases.
gocqltable is a wrapper around gocql that aims to simplify common operations.
gockle provides simple, mockable interfaces that wrap gocql types
scylladb is a fast Apache Cassandra-compatible NoSQL database
go-cql-driver is an CQL driver conforming to the built-in database/sql interface. It is good for simple use cases where the database/sql interface is wanted. The CQL driver is a wrapper around this project.
Other Projects
gocqldriver is the predecessor of gocql based on Go's database/sql package. This project isn't maintained anymore, because Cassandra wasn't a good fit for the traditional database/sql API. Use this package instead.
SEO
For some reason, when you Google golang cassandra, this project doesn't feature very highly in the result list. But if you Google go cassandra, then we're a bit higher up the list. So this is note to try to convince Google that golang is an alias for Go.
License
Copyright (c) 2012-2016 The gocql Authors. All rights reserved.
Use of this source code is governed by a BSD-style
license that can be found in the LICENSE file.
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