kv

KeyValue "kv"

Simple key-value interface backed by multiple backends (multiple sql engines through gorm, pure golang through badger DB; cloud scale through google datastore).

This is not meant for the high performance applications but rather quick prototyping for cases where simple get/upsert/del/iterate in enough to get started. The different backends are meants for various scaling scenarios and deployment needs.

Status

WIP/Experiment. Should not be used. (limited tests, poor code quality, fragile interfaces, etc)

PRs are welcome.

Usage

import "github.com/zatte/kv"

func main(){
  ctx  := context.Background()
  // gorm / sqlite3 in memory, limited transactional support. Not great for testing
  // db, err := kv.New("sqlite3:///file%3A%3Amemory%3A%3Fcache%3Dshared&mode=rwc")

  // gorm / sqlite3 in memory, limited transactional support. Not great for testing
  // db, err := kv.New("psql://user:password@host:port/database")
  // db, err := kv.New("mysql", "mysql://user:password@/dbname?charset=utf8&parseTime=True&loc=Local")
  // db, err := kv.New("mssql", "mssql://username:password@localhost:1433?database=dbname")

  // Badger DB In memory
  // db, err := kv.New("badger:///?memory=true")

  // Badger DB by path
  // db, err := kv.New("badger:///./badger.testing.db")

  // datastore, local emulator for testing / development
  // db, err := kv.New("datastore://" + os.Getenv("DATASTORE_PROJECT_ID"))

  // datastore based on project id
  // db, err := kv.New("datastore://google-cloud-project-id")

  db, err := kv.New("badger:///?memory=true")

  // Put, Get, Del
  err := db.Put(ctx, []byte("key"), []byte("value"))
  key, err := db.Get(ctx, []byte("key"))
  err := db.Delete(ctx, []byte("key"))
  
  // Create a transaction
  tx, err := db.NewTransaction(ctx, false) // read only transactions. Not supported by all backends but some. 
  defer tx.Discard()

  // Same as above: Put, Get, Del
  err := tx.Put(ctx, []byte("key"), []byte("value"))
  key, err := tx.Get(ctx, []byte("key"))
  err := tx.Delete(ctx, []byte("key"))

  // but transactions can also be have iterators 
  it, err := tx.Seek(ctx, []byte("inclusvie_start_key_utf8_sort_order"))
  defer it.Close()

  for key, val, err := it.Next(); err == nil; key, val, err = it.Next() {
    // process keys and values in order.
  }
}

Testing

Doesn't perform integration testing with external databaes except datastore.

gcloud beta emulators datastore start & 
$(gcloud beta emulators datastore env-init)
go test

TODO

• Add Create (failure on existing keys)
• Add Backend Redis
• Improve errors (atm all errors are ErrNotFound)
• Improve docs
• Integration testing with
• • MySQL
• • Postgres
• • MsSQL

License

Copyright 2020 Mikael Rapp, github.com/zatte

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

http://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.