instaclustr/gocql

Package gocql implements a fast and robust Cassandra client for theGo programming language.Project Website: https://gocql.github.io/API documentation: https://godoc.org/github.com/gocql/gocqlDiscussions: https://groups.google.com/forum/#!forum/gocqlSupported VersionsThe following matrix shows the versions of Go and Cassandra that are tested with the integration test suite as part of the CI build:Go/Cassandra2.1.x2.2.x3.0.x1.8yesyesyes1.9yesyesyesGocql 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 ModelIn 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.Installationgo get github.com/gocql/gocqlFeaturesModern Cassandra client using the native transportAutomatic type conversions between Cassandra and GoSupport for all common types including sets, lists and mapsCustom types can implement a Marshaler and Unmarshaler interfaceStrict type conversions without any loss of precisionBuilt-In support for UUIDs (version 1 and 4)Support for logged, unlogged and counter batchesCluster managementAutomatic reconnect on connection failures with exponential falloffRound robin distribution of queries to different hostsRound robin distribution of queries to different connections on a hostEach 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 nodesPolicy based connection pool with token aware and round-robin policy implementationsSupport for password authenticationIteration over paged results with configurable page sizeSupport for TLS/SSLOptional frame compression (using snappy)Automatic query preparationSupport for query tracingSupport for Cassandra 2.1+ binary protocol version 3Support for up to 32768 streamsSupport for tuple typesSupport for client side timestamps by defaultSupport for UDTs via a custom marshaller or struct tagsSupport for Cassandra 3.0+ binary protocol version 4An API to access the schema metadata of a given keyspacePerformanceWhile the driver strives to be highly performant, there are cases where it is difficult to test and verify. The driver is builtwith maintainability and code readability in mind first and then performance and features, as such every now and then performancemay degrade, if this occurs please report and issue and it will be looked at and remedied. The only time the driver copies data fromits read buffer is when it Unmarshal's data into supplied types.Some tips for getting more performance from the driver:Use the TokenAware policyUse many goroutines when doing inserts, the driver is asynchronous but provides a synchronous API, it can execute many queries concurrentlyTune query page sizeReading data from the network to unmarshal will incur a large amount of allocations, this can adversely affect the garbage collector, tune GOGCClose iterators after use to recycle byte buffersImportant Default Keyspace Changesgocql no longer supports executing "use " statements to simplify the library. The user still has theability to define the default keyspace for connections but now the keyspace can only be defined before asession is created. Queries can still access keyspaces by indicating the keyspace in the query:SELECT * FROM example2.table;Example of correct usage: cluster := gocql.NewCluster("192.168.1.1", "192.168.1.2", "192.168.1.3") cluster.Keyspace = "example" ... session, err := cluster.CreateSession()Example of incorrect usage: cluster := gocql.NewCluster("192.168.1.1", "192.168.1.2", "192.168.1.3") cluster.Keyspace = "example" ... session, err := cluster.CreateSession() if err = session.Query("use example2").Exec(); err != nil { log.Fatal(err) }This will result in an err being returned from the session.Query line as the user is trying to execute a "use"statement.Example/* Before you execute the program, Launch `cqlsh` and execute:create keyspace example with replication = { 'class' : 'SimpleStrategy', 'replication_factor' : 1 };create table example.tweet(timeline text, id UUID, text text, PRIMARY KEY(id));create index on example.tweet(timeline);*/package mainimport ( "fmt" "log" "github.com/gocql/gocql")func main() { // connect to the cluster cluster := gocql.NewCluster("192.168.1.1", "192.168.1.2", "192.168.1.3") cluster.Keyspace = "example" cluster.Consistency = gocql.Quorum session, _ := cluster.CreateSession() defer session.Close() // insert a tweet if err := session.Query(`INSERT INTO tweet (timeline, id, text) VALUES (?, ?, ?)`, "me", gocql.TimeUUID(), "hello world").Exec(); err != nil { log.Fatal(err) } var id gocql.UUID var text string /* Search for a specific set of records whose 'timeline' column matches * the value 'me'. The secondary index that we created earlier will be * used for optimizing the search */ if err := session.Query(`SELECT id, text FROM tweet WHERE timeline = ? LIMIT 1`, "me").Consistency(gocql.One).Scan(&id, &text); err != nil { log.Fatal(err) } fmt.Println("Tweet:", id, text) // list all tweets iter := session.Query(`SELECT id, text FROM tweet WHERE timeline = ?`, "me").Iter() for iter.Scan(&id, &text) { fmt.Println("Tweet:", id, text) } if err := iter.Close(); err != nil { log.Fatal(err) }}Data BindingThere 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.EcosystemThe 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.negronicql is gocql middleware for Negroni.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 typesscylladb is a fast Apache Cassandra-compatible NoSQL databaseOther Projectsgocqldriver 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.SEOFor 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.LicenseCopyright (c) 2012-2016 The gocql Authors. All rights reserved.Use of this source code is governed by a BSD-stylelicense that can be found in the LICENSE file.Further InformationSee Alex Lourie's blog "Query Idempotence in GoCql driver"