mirror of https://github.com/hashicorp/consul
94 lines
2.6 KiB
Markdown
94 lines
2.6 KiB
Markdown
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# go-memdb
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Provides the `memdb` package that implements a simple in-memory database
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built on immutable radix trees. The database provides Atomicity, Consistency
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and Isolation from ACID. Being that it is in-memory, it does not provide durability.
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The database is instantiated with a schema that specifies the tables and indicies
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that exist and allows transactions to be executed.
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The database provides the following:
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* Multi-Version Concurrency Control (MVCC) - By leveraging immutable radix trees
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the database is able to support any number of concurrent readers without locking,
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and allows a writer to make progress.
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* Transaction Support - The database allows for rich transactions, in which multiple
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objects are inserted, updated or deleted. The transactions can span multiple tables,
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and are applied atomically. The database provides atomicity and isolation in ACID
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terminology, such that until commit the updates are not visible.
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* Rich Indexing - Tables can support any number of indexes, which can be simple like
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a single field index, or more advanced compound field indexes. Certain types like
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UUID can be efficiently compressed from strings into byte indexes for reduces
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storage requirements.
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For the underlying immutable radix trees, see [go-immutable-radix](https://github.com/hashicorp/go-immutable-radix).
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Documentation
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=============
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The full documentation is available on [Godoc](http://godoc.org/github.com/hashicorp/go-memdb).
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Example
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=======
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Below is a simple example of usage
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```go
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// Create a sample struct
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type Person struct {
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Email string
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Name string
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Age int
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}
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// Create the DB schema
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schema := &memdb.DBSchema{
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Tables: map[string]*memdb.TableSchema{
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"person": &memdb.TableSchema{
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Name: "person",
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Indexes: map[string]*memdb.IndexSchema{
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"id": &memdb.IndexSchema{
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Name: "id",
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Unique: true,
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Indexer: &memdb.StringFieldIndex{Field: "Email"},
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},
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},
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},
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},
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}
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// Create a new data base
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db, err := memdb.NewMemDB(schema)
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if err != nil {
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panic(err)
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}
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// Create a write transaction
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txn := db.Txn(true)
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// Insert a new person
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p := &Person{"joe@aol.com", "Joe", 30}
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if err := txn.Insert("person", p); err != nil {
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panic(err)
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}
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// Commit the transaction
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txn.Commit()
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// Create read-only transaction
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txn = db.Txn(false)
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defer txn.Abort()
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// Lookup by email
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raw, err := txn.First("person", "id", "joe@aol.com")
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if err != nil {
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panic(err)
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}
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// Say hi!
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fmt.Printf("Hello %s!", raw.(*Person).Name)
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```
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