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main.go
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main.go
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package main
import (
"github.com/nutsdb/nutsdb"
"io/ioutil"
"log"
"os"
)
var (
db *nutsdb.DB
bucket string
err error
)
func init() {
fileDir := "/tmp/nutsdb_example"
files, _ := ioutil.ReadDir(fileDir)
for _, f := range files {
name := f.Name()
if name != "" {
err := os.RemoveAll(fileDir + "/" + name)
if err != nil {
panic(err)
}
}
}
db, _ = nutsdb.Open(
nutsdb.DefaultOptions,
nutsdb.WithDir(fileDir),
nutsdb.WithSegmentSize(1024*1024), // 1MB
)
if err != nil {
panic(err)
}
bucket = "bucketForString"
if err := db.Update(func(tx *nutsdb.Tx) error {
return tx.NewBucket(nutsdb.DataStructureBTree, bucket)
}); err != nil {
log.Fatal(err)
}
}
func main() {
// If we use tx.GetRange on a non-exist key, it will throw an error about key not found
getRange("non-exist", 0, 0) // key not found
put("key", "This is a test value")
// If we use tx.GetRange with a pair of start and end which start is greater than end, it will throw an error.
getRange("key", 5, 3) // start is greater than end
// When start < end but start is greater than the size of value, it will return an empty value.
getRange("key", 100, 120) // got value: ''
// When start is less than the size of value, but end is greater. It will use value[start:] as its return.
getRange("key", 10, 100) // got value: 'test value'
// When end is less than the size of value. It will use value[start:end+1] as its return. This is same with Redis.
getRange("key", 10, 13) // got value: 'test'
}
func put(key, value string) {
if err := db.Update(func(tx *nutsdb.Tx) error {
return tx.Put(bucket, []byte(key), []byte(value), nutsdb.Persistent)
}); err != nil {
log.Println(err)
}
}
func getRange(key string, start, end int) {
if err := db.View(func(tx *nutsdb.Tx) error {
value, err := tx.GetRange(bucket, []byte(key), start, end)
if err != nil {
return err
}
log.Printf("got value: '%s'", string(value))
return nil
}); err != nil {
log.Println(err)
}
}