diff --git a/builder/codegen.js b/builder/codegen.js
index 9228fd2..5b2c0ed 100644
--- a/builder/codegen.js
+++ b/builder/codegen.js
@@ -122,10 +122,12 @@ module.exports = function generateCode (hyperdb) {
   return str
 }
 
-function toArrayFunction (fn) {
+function toArrowFunction (str, async) {
+  let fn = genFunc()(str).toString()
   const i = fn.indexOf('(')
   const isArrow = !fn.slice(0, i).includes('function')
   fn = fn.slice(i)
+  if (async) fn = 'async ' + fn
   if (isArrow) return fn
   return fn.replace('{', '=> {')
 }
@@ -138,9 +140,8 @@ function generateCommonPrefix (id, type) {
   str += '\n'
 
   if (type.isMapped) {
-    const fn = genFunc()
-    fn(type.map)
-    str += `const ${id}_map = ${toArrayFunction(fn.toString())}\n`
+    str += `// ${s(type.fqn)} has the following schema defined key map\n`
+    str += `const ${id}_map = ${toArrowFunction(type.map, false)}\n`
     str += '\n'
   }
 
@@ -165,6 +166,12 @@ function generateCommonPrefix (id, type) {
 function generateCollectionDefinition (id, collection) {
   let str = generateCommonPrefix(id, collection)
 
+  if (collection.trigger) {
+    str += `// ${s(collection.fqn)} has the following schema defined trigger\n`
+    str += `const ${id}_trigger = ${toArrowFunction(collection.trigger, true)}\n`
+    str += '\n'
+  }
+
   str += `// ${s(collection.fqn)} reconstruction function\n`
   str += `function ${id}_reconstruct (version, keyBuf, valueBuf) {\n`
   str += '  // TODO: This should be fully code generated\n'
@@ -185,6 +192,7 @@ function generateCollectionDefinition (id, collection) {
   str += `  name: ${s(collection.fqn)},\n`
   str += `  id: ${collection.id},\n`
   str += `  stats: ${collection.stats},\n`
+  str += `  trigger: ${collection.trigger ? id + '_trigger' : 'null'},\n`
   str += `  encodeKey: ${generateEncodeCollectionKey(id, collection)},\n`
   str += `  encodeKeyRange: ${generateEncodeKeyRange(id, collection)},\n`
   str += `  encodeValue: ${generateEncodeCollectionValue(collection)},\n`
diff --git a/builder/index.js b/builder/index.js
index c2a6818..29bdbec 100644
--- a/builder/index.js
+++ b/builder/index.js
@@ -75,6 +75,7 @@ class Collection extends DBType {
 
     this.key = description.key || []
     this.fullKey = this.key
+    this.trigger = (typeof description.trigger === 'function') ? description.trigger.toString() : description.trigger
 
     this.keyEncoding = []
     this.valueEncoding = this.fqn + '/value'
diff --git a/index.js b/index.js
index 64eaa55..b1a329e 100644
--- a/index.js
+++ b/index.js
@@ -301,7 +301,7 @@ class HyperDB {
     const collection = this.definition.resolveCollection(collectionName)
     if (collection === null) return null
 
-    const key = collection.encodeKey(doc)
+    const key = b4a.isBuffer(doc) ? doc : collection.encodeKey(doc)
 
     const u = this.updates.get(key)
     const value = u !== null ? u.value : await this.engine.get(this.engineSnapshot, key)
@@ -348,6 +348,11 @@ class HyperDB {
     return value
   }
 
+  // TODO: needs to wait for pending inserts/deletes and then lock all future ones whilst it runs
+  _runTrigger (collection, key, doc) {
+    return collection.trigger(this, key, doc, this.context)
+  }
+
   async delete (collectionName, doc) {
     maybeClosed(this)
 
@@ -361,6 +366,7 @@ class HyperDB {
     let prevValue = null
     this.updates.mutating++
     try {
+      if (collection.trigger !== null) await this._runTrigger(collection, key, doc)
       prevValue = await this._getPrev(key, collection)
     } finally {
       this.updates.mutating--
@@ -400,6 +406,7 @@ class HyperDB {
     let prevValue = null
     this.updates.mutating++
     try {
+      if (collection.trigger !== null) await this._runTrigger(collection, key, doc)
       prevValue = await this._getPrev(key, collection)
     } finally {
       this.updates.mutating--
diff --git a/lib/engine/rocks.js b/lib/engine/rocks.js
index 5c96bcb..5b06efb 100644
--- a/lib/engine/rocks.js
+++ b/lib/engine/rocks.js
@@ -25,6 +25,7 @@ module.exports = class RocksEngine {
     this.clock = 0
     this.refs = 0
     this.db = typeof storage === 'object' ? storage : new RocksDB(storage)
+    this.db.ready().catch(noop)
   }
 
   get closed () {
@@ -103,3 +104,5 @@ async function getWrapped (read, key, value) {
 function getSnapshot (snap) {
   return snap === null ? null : snap.snapshot
 }
+
+function noop () {}
diff --git a/package.json b/package.json
index 8f6d4d5..8e663c2 100644
--- a/package.json
+++ b/package.json
@@ -22,7 +22,7 @@
     "generate-function": "^2.3.1",
     "generate-object-property": "^2.0.0",
     "generate-string": "^1.0.1",
-    "hyperschema": "^0.0.14",
+    "hyperschema": "^0.0.16",
     "rocksdb-native": "^2.3.1",
     "streamx": "^2.20.0"
   },
diff --git a/test/fixtures/definition.js b/test/fixtures/definition.js
index b5afd6f..b858bd5 100644
--- a/test/fixtures/definition.js
+++ b/test/fixtures/definition.js
@@ -22,6 +22,9 @@ const struct = {
 
 const membersCollection = {
   name: 'members',
+  stats: false,
+  id: 0,
+  trigger: null,
   encodeKey (doc) {
     return memberKey.encode([doc.id])
   },
@@ -40,6 +43,8 @@ const membersCollection = {
 const membersByAgeIndex = {
   name: 'members/by-age',
   offset: 0,
+  stats: false,
+  id: 1,
   encodeKeys (doc) {
     return [memberByAge.encode([doc.age, doc.id])]
   },
diff --git a/test/fixtures/generated/1/hyperdb/db.json b/test/fixtures/generated/1/hyperdb/db.json
index 331f659..544c054 100644
--- a/test/fixtures/generated/1/hyperdb/db.json
+++ b/test/fixtures/generated/1/hyperdb/db.json
@@ -12,6 +12,7 @@
         "@db/members-by-age"
       ],
       "schema": "@db/member",
+      "derived": false,
       "key": [
         "id"
       ]
diff --git a/test/fixtures/generated/1/hyperdb/index.js b/test/fixtures/generated/1/hyperdb/index.js
index e54c97e..9220d5a 100644
--- a/test/fixtures/generated/1/hyperdb/index.js
+++ b/test/fixtures/generated/1/hyperdb/index.js
@@ -36,6 +36,7 @@ const collection0 = {
   name: '@db/members',
   id: 0,
   stats: false,
+  trigger: null,
   encodeKey: function encodeKey (record) {
     const key = [record.id]
     return collection0_key.encode(key)
@@ -80,9 +81,8 @@ const index0 = {
   name: '@db/members-by-age',
   id: 1,
   stats: false,
-  encodeKeys: function encodeKeys (record) {
-    const key = [record.age, record.id]
-    return [index0_key.encode(key)]
+  encodeKeys: function encodeKeys (record, context) {
+    return [index0_key.encode([record.age, record.id])]
   },
   encodeKeyRange: function encodeKeyRange ({ gt, lt, gte, lte } = {}) {
     return index0_key.encodeRange({
diff --git a/test/fixtures/generated/2/hyperdb/db.json b/test/fixtures/generated/2/hyperdb/db.json
index e73f2cf..f41e745 100644
--- a/test/fixtures/generated/2/hyperdb/db.json
+++ b/test/fixtures/generated/2/hyperdb/db.json
@@ -12,6 +12,7 @@
         "@db/members-by-age"
       ],
       "schema": "@db/member",
+      "derived": false,
       "key": [
         "id"
       ]
@@ -24,6 +25,7 @@
       "type": 1,
       "indexes": [],
       "schema": "stats",
+      "derived": false,
       "key": [
         "id"
       ]
diff --git a/test/fixtures/generated/2/hyperdb/index.js b/test/fixtures/generated/2/hyperdb/index.js
index 09c43a7..6ec7589 100644
--- a/test/fixtures/generated/2/hyperdb/index.js
+++ b/test/fixtures/generated/2/hyperdb/index.js
@@ -36,6 +36,7 @@ const collection0 = {
   name: '@db/members',
   id: 0,
   stats: true,
+  trigger: null,
   encodeKey: function encodeKey (record) {
     const key = [record.id]
     return collection0_key.encode(key)
@@ -86,6 +87,7 @@ const collection1 = {
   name: 'stats',
   id: 1,
   stats: false,
+  trigger: null,
   encodeKey: function encodeKey (record) {
     const key = [record.id]
     return collection1_key.encode(key)
@@ -130,9 +132,8 @@ const index0 = {
   name: '@db/members-by-age',
   id: 2,
   stats: false,
-  encodeKeys: function encodeKeys (record) {
-    const key = [record.age, record.id]
-    return [index0_key.encode(key)]
+  encodeKeys: function encodeKeys (record, context) {
+    return [index0_key.encode([record.age, record.id])]
   },
   encodeKeyRange: function encodeKeyRange ({ gt, lt, gte, lte } = {}) {
     return index0_key.encodeRange({
diff --git a/test/fixtures/generated/2/hyperdb/messages.js b/test/fixtures/generated/2/hyperdb/messages.js
index 153e5ff..b9b9a9b 100644
--- a/test/fixtures/generated/2/hyperdb/messages.js
+++ b/test/fixtures/generated/2/hyperdb/messages.js
@@ -1,9 +1,9 @@
 // This file is autogenerated by the hyperschema compiler
-// Schema Version: 2
+// Schema Version: 1
 /* eslint-disable camelcase */
 /* eslint-disable quotes */
 
-const VERSION = 2
+const VERSION = 1
 const { c } = require('hyperschema/runtime')
 
 // eslint-disable-next-line no-unused-vars
@@ -61,8 +61,8 @@ const encoding2 = {
   },
   decode (state) {
     const res = {}
-    if (version >= 2) res.id = 0
-    if (version >= 2) res.count = 0
+    res.id = 0
+    res.count = 0
 
     res.id = c.uint.decode(state)
     res.count = c.uint.decode(state)
@@ -81,7 +81,7 @@ const encoding3 = {
   },
   decode (state) {
     const res = {}
-    if (version >= 2) res.count = 0
+    res.count = 0
 
     res.count = c.uint.decode(state)