ssdb(sorted string database) is a library that provides persistent key value for storing data on disk. It is an implementation of LevelDB in Go, including every feature in LevelDB. The core storage architecture is a Log Structured Merge Tree.
package main
import (
"fmt"
"os"
"ssdb"
"ssdb/db"
)
func main() {
options := ssdb.NewOptions()
options.CreateIfMissing = true
var (
d ssdb.DB
err error
)
if d, err = db.Open(options, "/tmp/test_db"); err != nil {
fmt.Fprintf(os.Stderr, "Open db error: %v.\n", err)
os.Exit(1)
}
defer d.Close()
key := []byte("hello")
if _, err = d.Get(ssdb.NewReadOptions(), key); !ssdb.IsNotFound(err) {
fmt.Fprintln(os.Stderr, "Expect value not found.")
os.Exit(1)
}
value := []byte("world")
if err = d.Put(ssdb.NewWriteOptions(), key, value); err != nil {
fmt.Fprintf(os.Stderr, "Put kv error: %v.\n", err)
os.Exit(1)
}
var v []byte
if v, err = d.Get(ssdb.NewReadOptions(), key); err != nil || string(v) != "world"{
fmt.Fprintf(os.Stderr, "Get value error: %v.\n", err)
os.Exit(1)
}
}More examples can be found here.
A benchmark program dbbench is written in order to test performance.
SSDB: version 1.22
Date: 2021-08-03T21:50:13
CPU: 8
CPUCache: 8192 KB
Keys: 16 bytes each
Values: 100 bytes each (50 bytes after compression)
Entries: 1000000
RawSize: 110.6 MB (estimated)
FileSize: 62.9 MB (estimated)
fillseq : 5.922 micros/op; 18.7 MB/s
fillsync : 600.972 micros/op; 0.2 MB/s (10000 ops)
fillrandom : 7.661 micros/op; 14.4 MB/s
overwrite : 7.917 micros/op; 14.0 MB/s
readrandom : 8.105 micros/op; (approximately 12,338 reads per second)
readseq : 0.548 micros/op; 111.3 MB/s
readreverse : 0.803 micros/op; 76.0 MB/s
Read performance after compactions is better.
readrandom : 5.015 micros/op; (approximately 19,940 reads per second)
readseq : 0.273 micros/op; 223.3 MB/s
readreverse : 0.338 micros/op; 180.7 MB/s
Read performance improves if enough memory cache are provided, so the uncompressed block can hold in memory.
readrandom : 5.153 micros/op; (approximately 19,406 reads per second before compaction)
readrandom : 2.838 micros/op; (approximately 35,236 reads per second after compaction)
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