README.md
# JLevelDB
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---
JLevelDB is an implementation of the
[LevelDB key/value database](https://code.google.com/p/leveldb) in the
[Go programming language](https://golang.org), based on
[GoLevelDB](https://github.com/syndtr/goleveldb)
---
## Requirements
- Go 1.17 or later
---
## Availability
- [GitHub](https://github.com/johnsonjh/jleveldb)
---
## License
- [BSD-2-Clause License](<https://tldrlegal.com/license/bsd-2-clause-license-(freebsd)>)
---
## Examples
- 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()
...
```
---