From 7984cb6859c8e61af0990352e09c805d8d546feb Mon Sep 17 00:00:00 2001
From: Carson Farmer <carson.farmer@gmail.com>
Date: Fri, 13 Dec 2019 11:48:54 -0800
Subject: [PATCH 1/3] feat: optimise prefix search

Signed-off-by: Carson Farmer <carson.farmer@gmail.com>
---
 src/index.js | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/src/index.js b/src/index.js
index 70a397f..b510c7c 100644
--- a/src/index.js
+++ b/src/index.js
@@ -105,12 +105,23 @@ class LevelDatastore {
       values = !q.keysOnly
     }
 
+    let opts = {
+      keys: true,
+      values: values,
+      keyAsBuffer: true
+    }
+
+    // Let the db do the prefix matching
+    if (q.prefix != null) {
+      const prefix = q.prefix.toString()
+      // Match keys greater than or equal to `prefix` and
+      opts.gte = prefix
+      // less than `prefix` + \xFF (hex escape sequence)
+      opts.lt = prefix + '\xFF'
+    }
+
     let it = levelIteratorToIterator(
-      this.db.db.iterator({
-        keys: true,
-        values: values,
-        keyAsBuffer: true
-      })
+      this.db.db.iterator(opts)
     )
 
     it = map(it, ({ key, value }) => {
@@ -121,10 +132,6 @@ class LevelDatastore {
       return res
     })
 
-    if (q.prefix != null) {
-      it = filter(it, e => e.key.toString().startsWith(q.prefix))
-    }
-
     if (Array.isArray(q.filters)) {
       it = q.filters.reduce((it, f) => filter(it, f), it)
     }

From 0d4e6fb56d11bf668e49a0db158d642a6a0252f0 Mon Sep 17 00:00:00 2001
From: Carson Farmer <carson.farmer@gmail.com>
Date: Fri, 13 Dec 2019 12:00:20 -0800
Subject: [PATCH 2/3] style: fix linter issue

Signed-off-by: Carson Farmer <carson.farmer@gmail.com>
---
 src/index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/index.js b/src/index.js
index b510c7c..ed0a2a0 100644
--- a/src/index.js
+++ b/src/index.js
@@ -105,7 +105,7 @@ class LevelDatastore {
       values = !q.keysOnly
     }
 
-    let opts = {
+    const opts = {
       keys: true,
       values: values,
       keyAsBuffer: true

From a18813df46f69964df23c9f8d4c883aa0cf4f6c9 Mon Sep 17 00:00:00 2001
From: Carson Farmer <carson.farmer@gmail.com>
Date: Mon, 16 Dec 2019 09:38:47 -0800
Subject: [PATCH 3/3] chore: remove avoid reaching into internal db

Signed-off-by: Carson Farmer <carson.farmer@gmail.com>
---
 src/index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/index.js b/src/index.js
index ed0a2a0..a3760f7 100644
--- a/src/index.js
+++ b/src/index.js
@@ -121,7 +121,7 @@ class LevelDatastore {
     }
 
     let it = levelIteratorToIterator(
-      this.db.db.iterator(opts)
+      this.db.iterator(opts)
     )
 
     it = map(it, ({ key, value }) => {