In-memory & embedded databases

Several VFSes back a database with memory or a read-only buffer instead of the OS filesystem. Pick by the isolation contract you want.

// Snapshot-isolation reads + atomic-publish writes.
import "gosqlite.org/vfs/mvcc"
name, fs, _ := mvcc.New(mvcc.Options{})
defer fs.Close()
db, _ := sql.Open("sqlite", "file:/shared.db?vfs="+name)   // SHARED
db2, _ := sql.Open("sqlite", "file:scratch.db?vfs="+name)  // PRIVATE

// Direct per-page store, no MVCC — writes visible to readers instantly.
import "gosqlite.org/vfs/memdb"
name, fs, _ := memdb.New(memdb.Options{})
defer fs.Close()
db, _ := sql.Open("sqlite", "file:/cache.db?vfs="+name)

vfs/mvcc gives reader snapshots at lock-acquire time and republishes the snapshot atomically on commit; pair with the standard busy-timeout retry for concurrent writers. vfs/memdb is the smaller-surface alternative — no snapshot copy on commit; concurrent writers see each other immediately. Both use the leading-/ convention (file:/name) for shared stores vs no-leading-slash (file:name) for per-handle private stores. Runnable: examples/features/vfs/mvcc/, examples/features/vfs/memdb/.

For simple shared in-memory tests without a VFS, sqlite.OpenShared(name) is the one-liner (Configuration).

import "gosqlite.org/vfs"

//go:embed seed.db
var seed embed.FS

name, _, _ := vfs.New(seed)
db, _ := sql.Open("sqlite3", "file:seed.db?vfs="+name+"&mode=ro")

vfs.New(fs.FS) exposes any read-only io/fs.FS (embed.FS, fstest.MapFS, zip-fs) as a VFS. Runnable: examples/features/vfs/embed/.

When you already have a []byte or io.ReaderAt, use the lighter vfs.NewReader:

bs, _ := os.ReadFile("seed.db")
name, fs, _ := vfs.NewReader(bytes.NewReader(bs), int64(len(bs)))
defer fs.Close()

db, _ := sql.Open("sqlite", "file:db?vfs="+name+"&mode=ro")

The file name inside the VFS is always db. Useful for shipping a sealed read-only DB as a Go variable, or mmap-backed buffers that don’t want to round-trip through fs.FS.

To back a writable database with your own Go storage, see Custom VFS.