README
¶
Go: key/value store, redis
key/value store
A key-value store stores data with key-value pair using data structures like dictionary, map, or hash. It work much different than traditional SQL database, or relational database, so it's often called NoSQL database. None is better than the other. If you have relation-less data and need fast-retrieval by providing the key, the key-value database is a better choice. If you deal with data sets, each of which relates to another in complicated ways, the relational-database is the right choice.
The simplest way is to use your file systems as a key-value storage:
package main
import (
"crypto/sha512"
"encoding/hex"
"fmt"
"io/ioutil"
"log"
"os"
"strings"
)
func exist(fpath string) bool {
// Does a directory exist
st, err := os.Stat(fpath)
if err != nil {
return false
}
if st.IsDir() {
return true
}
if _, err := os.Stat(fpath); err != nil {
if strings.Contains(err.Error(), "no such file") {
return false
}
}
return true
}
func getHash(bt []byte) string {
if bt == nil {
return ""
}
h := sha512.New()
h.Write(bt)
sha512Hash := hex.EncodeToString(h.Sum(nil))
return sha512Hash
}
func main() {
var events = []string{
"Hello World!",
"Hello World!",
"different",
}
for _, event := range events {
eventHash := getHash([]byte(event))
if !exist(eventHash) {
if err := ioutil.WriteFile(eventHash, nil, 0644); err != nil {
log.Fatal(err)
}
fmt.Println("Saved", event, "with", eventHash)
} else {
fmt.Println("Found duplicate events:", event)
}
}
}
/*
Saved Hello World! with 861844d6704e8573fec34d967e20bcfef3d424cf48be04e6dc08f2bd58c729743371015ead891cc3cf1c9d34b49264b510751b1ff9e537937bc46b5d6ff4ecc8
Found duplicate events: Hello World!
Saved different with 49d5b8799558e22d3890d03b56a6c7a46faa1a7d216c2df22507396242ab3540e2317b870882b2384d707254333a8439fd3ca191e93293f745786ff78ef069f8
*/
redis
Redis is an open source, BSD licensed, advanced key-value cache and store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets, sorted sets, bitmaps, hyperloglogs.
package main
import (
"fmt"
"log"
"github.com/garyburd/redigo/redis"
)
func main() {
c, err := redis.Dial("tcp", ":6379")
if err != nil {
log.Fatal(err)
}
defer c.Close()
// SET command only lets you have one value for the key
c.Do("SET", "MY_KEY", "MY_VALUE")
// HSET lets you have multiple fields and values
c.Do("HSET", "myhash", "field1", "Hello")
// myhash = { field1 : "Hello" }
val1, err := redis.String(c.Do("GET", "MY_KEY"))
if err != nil {
fmt.Println("key not found")
}
fmt.Println(val1)
// MY_VALUE
val2, err := redis.String(c.Do("HGET", "myhash", "field1"))
if err != nil {
fmt.Println("key not found")
}
fmt.Println(val2)
// Hello
}
Directories