108 lines
2.3 KiB
Markdown
108 lines
2.3 KiB
Markdown
This is an implementation of the [LevelDB key/value database](http:code.google.com/p/leveldb) in the [Go programming language](http:golang.org).
|
|
|
|
[](https://travis-ci.org/syndtr/goleveldb)
|
|
|
|
Installation
|
|
-----------
|
|
|
|
go get github.com/syndtr/goleveldb/leveldb
|
|
|
|
Requirements
|
|
-----------
|
|
|
|
* Need at least `go1.4` or newer.
|
|
|
|
Usage
|
|
-----------
|
|
|
|
Create or open a database:
|
|
```go
|
|
// The returned DB instance is safe for concurrent use. Which mean that all
|
|
// DB's methods may be called concurrently from multiple goroutine.
|
|
db, err := leveldb.OpenFile("path/to/db", nil)
|
|
...
|
|
defer db.Close()
|
|
...
|
|
```
|
|
Read or modify the database content:
|
|
```go
|
|
// Remember that the contents of the returned slice should not be modified.
|
|
data, err := db.Get([]byte("key"), nil)
|
|
...
|
|
err = db.Put([]byte("key"), []byte("value"), nil)
|
|
...
|
|
err = db.Delete([]byte("key"), nil)
|
|
...
|
|
```
|
|
|
|
Iterate over database content:
|
|
```go
|
|
iter := db.NewIterator(nil, nil)
|
|
for iter.Next() {
|
|
// Remember that the contents of the returned slice should not be modified, and
|
|
// only valid until the next call to Next.
|
|
key := iter.Key()
|
|
value := iter.Value()
|
|
...
|
|
}
|
|
iter.Release()
|
|
err = iter.Error()
|
|
...
|
|
```
|
|
Seek-then-Iterate:
|
|
```go
|
|
iter := db.NewIterator(nil, nil)
|
|
for ok := iter.Seek(key); ok; ok = iter.Next() {
|
|
// Use key/value.
|
|
...
|
|
}
|
|
iter.Release()
|
|
err = iter.Error()
|
|
...
|
|
```
|
|
Iterate over subset of database content:
|
|
```go
|
|
iter := db.NewIterator(&util.Range{Start: []byte("foo"), Limit: []byte("xoo")}, nil)
|
|
for iter.Next() {
|
|
// Use key/value.
|
|
...
|
|
}
|
|
iter.Release()
|
|
err = iter.Error()
|
|
...
|
|
```
|
|
Iterate over subset of database content with a particular prefix:
|
|
```go
|
|
iter := db.NewIterator(util.BytesPrefix([]byte("foo-")), nil)
|
|
for iter.Next() {
|
|
// Use key/value.
|
|
...
|
|
}
|
|
iter.Release()
|
|
err = iter.Error()
|
|
...
|
|
```
|
|
Batch writes:
|
|
```go
|
|
batch := new(leveldb.Batch)
|
|
batch.Put([]byte("foo"), []byte("value"))
|
|
batch.Put([]byte("bar"), []byte("another value"))
|
|
batch.Delete([]byte("baz"))
|
|
err = db.Write(batch, nil)
|
|
...
|
|
```
|
|
Use bloom filter:
|
|
```go
|
|
o := &opt.Options{
|
|
Filter: filter.NewBloomFilter(10),
|
|
}
|
|
db, err := leveldb.OpenFile("path/to/db", o)
|
|
...
|
|
defer db.Close()
|
|
...
|
|
```
|
|
Documentation
|
|
-----------
|
|
|
|
You can read package documentation [here](http:godoc.org/github.com/syndtr/goleveldb).
|