66 lines
2.0 KiB
Go
66 lines
2.0 KiB
Go
/*
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Package levigo provides the ability to create and access LevelDB databases.
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levigo.Open opens and creates databases.
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opts := levigo.NewOptions()
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opts.SetCache(levigo.NewLRUCache(3<<30))
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opts.SetCreateIfMissing(true)
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db, err := levigo.Open("/path/to/db", opts)
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The DB struct returned by Open provides DB.Get, DB.Put and DB.Delete to modify
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and query the database.
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ro := levigo.NewReadOptions()
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wo := levigo.NewWriteOptions()
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// if ro and wo are not used again, be sure to Close them.
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data, err := db.Get(ro, []byte("key"))
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...
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err = db.Put(wo, []byte("anotherkey"), data)
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...
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err = db.Delete(wo, []byte("key"))
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For bulk reads, use an Iterator. If you want to avoid disturbing your live
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traffic while doing the bulk read, be sure to call SetFillCache(false) on the
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ReadOptions you use when creating the Iterator.
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ro := levigo.NewReadOptions()
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ro.SetFillCache(false)
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it := db.NewIterator(ro)
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defer it.Close()
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for it.Seek(mykey); it.Valid(); it.Next() {
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munge(it.Key(), it.Value())
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}
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if err := it.GetError(); err != nil {
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...
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}
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Batched, atomic writes can be performed with a WriteBatch and
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DB.Write.
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wb := levigo.NewWriteBatch()
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// defer wb.Close or use wb.Clear and reuse.
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wb.Delete([]byte("removed"))
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wb.Put([]byte("added"), []byte("data"))
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wb.Put([]byte("anotheradded"), []byte("more"))
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err := db.Write(wo, wb)
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If your working dataset does not fit in memory, you'll want to add a bloom
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filter to your database. NewBloomFilter and Options.SetFilterPolicy is what
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you want. NewBloomFilter is amount of bits in the filter to use per key in
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your database.
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filter := levigo.NewBloomFilter(10)
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opts.SetFilterPolicy(filter)
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db, err := levigo.Open("/path/to/db", opts)
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If you're using a custom comparator in your code, be aware you may have to
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make your own filter policy object.
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This documentation is not a complete discussion of LevelDB. Please read the
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LevelDB documentation <http://code.google.com/p/leveldb> for information on
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its operation. You'll find lots of goodies there.
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*/
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package levigo
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