update docs

postgres/batch.go

@@ -29,7 +29,6 @@ type Batch struct {
 }
 
 // NewBatch returns a ethdb.Batch interface for PG-IPFS
-//
 func NewBatch(db *sqlx.DB, tx *sqlx.Tx) ethdb.Batch {
 	b := &Batch{
 		db: db,

postgres/database.go

@@ -183,7 +183,7 @@ func (d *Database) Compact(start []byte, limit []byte) error {
 // NewBatch creates a write-only database that buffers changes to its host db
 // until a final write is called
 func (d *Database) NewBatch() ethdb.Batch {
-	return NewBatch(d.db)
+	return NewBatch(d.db, nil)
 }
 
 // NewIterator satisfies the ethdb.Iteratee interface

postgres/doc.md

@@ -0,0 +1,41 @@
+## ipfs-ethdb
+
+IPFS has been [extended](https://github.com/vulcanize/go-ipfs/releases/tag/v0.4.22-alpha) to [use Postgres](https://github.com/vulcanize/go-ipfs-config/releases/tag/v0.0.8-alpha) as a backing [datastore](https://github.com/ipfs/go-ds-sql/tree/master/postgres).
+Interfacing directly with the IPFS-backing Postgres database has some advantages over using the blockservice interface.
+Namely, batching of IPFS writes with other Postgres writes and avoiding lock contention on the ipfs repository (lockfile located at the `IPFS_PATH`).
+The downside is that we forgo the block-exchange capabilities of the blockservice, and are only able to fetch data contained in the local datastore.
+
+
+## Usage
+To use this module import it and build an ethdb interface around an instance of [sqlx.DB](https://github.com/jmoiron/sqlx), you can then
+employ it as you would the blockservice-based ethdbs.
+
+```go
+package main
+
+import (
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/state"
+	"github.com/ethereum/go-ethereum/core/state/snapshot"
+	"github.com/ethereum/go-ethereum/trie"
+	"github.com/jmoiron/sqlx"
+	"github.com/vulcanize/ipfs-ethdb/postgres"
+)
+
+func main() {
+    connectStr := "postgresql://localhost:5432/vulcanize_testing?sslmode=disable"
+    db, _ := sqlx.Connect("postgres", connectStr)
+
+    kvs := pgipfsethdb.NewKeyValueStore(db)
+    trieDB := trie.NewDatabase(kvs)
+    t, _ := trie.New(common.Hash{}, trieDB)
+    trieNodeIterator := t.NodeIterator([]byte{})
+    // do stuff with trie node iterator
+
+    database := pgipfsethdb.NewDatabase(db)
+    stateDatabase := state.NewDatabase(database)
+    stateDB, _ := state.New(common.Hash{}, stateDatabase, nil)
+    stateDBNodeIterator := state.NewNodeIterator(stateDB)
+    // do stuff with the statedb node iterator
+}
+```