diff --git a/.gitignore b/.gitignore
index b6e4761..051b90c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -127,3 +127,7 @@ dmypy.json
 
 # Pyre type checker
 .pyre/
+
+# test JS dependencies
+tests/node_modules
+tests/package-lock.json
diff --git a/tests/test_ystore.py b/tests/test_ystore.py
index 858a570..ecbd1a4 100644
--- a/tests/test_ystore.py
+++ b/tests/test_ystore.py
@@ -1,7 +1,11 @@
 import asyncio
+import os
 import tempfile
+import time
 from pathlib import Path
+from unittest.mock import patch
 
+import aiosqlite
 import pytest
 
 from ypy_websocket.ystore import SQLiteYStore, TempFileYStore
@@ -25,6 +29,9 @@ class MyTempFileYStore(TempFileYStore):
 class MySQLiteYStore(SQLiteYStore):
     db_path = str(Path(tempfile.mkdtemp(prefix="test_sql_")) / "ystore.db")
 
+    def __del__(self):
+        os.remove(self.db_path)
+
 
 @pytest.mark.asyncio
 @pytest.mark.parametrize("YStore", (MyTempFileYStore, MySQLiteYStore))
@@ -44,3 +51,29 @@ async def test_file_ystore(YStore):
         assert d == data[i]  # data
         assert m == bytes(i)  # metadata
         i += 1
+
+
+@pytest.mark.asyncio
+async def test_document_ttl_sqlite_ystore():
+    store_name = "my_store"
+    ystore = MySQLiteYStore(store_name, metadata_callback=MetadataCallback())
+
+    await ystore.write(b"a")
+    async with aiosqlite.connect(ystore.db_path) as db:
+        assert (await (await db.execute("SELECT count(*) FROM yupdates")).fetchone())[0] == 1
+
+    now = time.time()
+
+    # assert that adding a record before document TTL doesn't delete document history
+    with patch("time.time") as mock_time:
+        mock_time.return_value = now
+        await ystore.write(b"b")
+        async with aiosqlite.connect(ystore.db_path) as db:
+            assert (await (await db.execute("SELECT count(*) FROM yupdates")).fetchone())[0] == 2
+
+    # assert that adding a record after document TTL deletes previous document history
+    with patch("time.time") as mock_time:
+        mock_time.return_value = now + ystore.document_ttl + 1000
+        await ystore.write(b"c")
+        async with aiosqlite.connect(ystore.db_path) as db:
+            assert (await (await db.execute("SELECT count(*) FROM yupdates")).fetchone())[0] == 1
diff --git a/ypy_websocket/ystore.py b/ypy_websocket/ystore.py
index 0c6d3e8..910ad22 100644
--- a/ypy_websocket/ystore.py
+++ b/ypy_websocket/ystore.py
@@ -1,7 +1,7 @@
 import asyncio
 import tempfile
+import time
 from abc import ABC, abstractmethod
-from datetime import datetime
 from pathlib import Path
 from typing import AsyncIterator, Callable, Optional, Tuple
 
@@ -126,6 +126,10 @@ class MySQLiteYStore(SQLiteYStore):
     """
 
     db_path: str = "ystore.db"
+    # Determines the "time to live" for all documents, i.e. how recent the
+    # latest update of a document must be before purging document history.
+    # Defaults to 1 day.
+    document_ttl: int = 24 * 60 * 60
     path: str
     db_created: asyncio.Event
 
@@ -138,7 +142,10 @@ def __init__(self, path: str, metadata_callback: Optional[Callable] = None):
     async def create_db(self):
         async with aiosqlite.connect(self.db_path) as db:
             await db.execute(
-                "CREATE TABLE IF NOT EXISTS yupdates (path TEXT, yupdate BLOB, metadata BLOB, timestamp TEXT)"
+                "CREATE TABLE IF NOT EXISTS yupdates (path TEXT NOT NULL, yupdate BLOB, metadata BLOB, timestamp REAL NOT NULL)"
+            )
+            await db.execute(
+                "CREATE INDEX IF NOT EXISTS idx_yupdates_path_timestamp ON yupdates (path, timestamp)"
             )
             await db.commit()
         self.db_created.set()
@@ -163,8 +170,21 @@ async def write(self, data: bytes) -> None:
         await self.db_created.wait()
         metadata = await self.get_metadata()
         async with aiosqlite.connect(self.db_path) as db:
+            # first, determine time elapsed since last update
+            cursor = await db.execute(
+                "SELECT timestamp FROM yupdates WHERE path = ? ORDER BY timestamp DESC LIMIT 1",
+                (self.path,),
+            )
+            row = await cursor.fetchone()
+            diff = (time.time() - row[0]) if row else 0
+
+            # if diff > document_ttl, delete document history
+            if diff > self.document_ttl:
+                await db.execute("DELETE FROM yupdates WHERE path = ?", (self.path,))
+
+            # finally, write this update to the DB
             await db.execute(
                 "INSERT INTO yupdates VALUES (?, ?, ?, ?)",
-                (self.path, data, metadata, datetime.utcnow()),
+                (self.path, data, metadata, time.time()),
             )
             await db.commit()