Remove checkpoint_ns from primary keys.

At the same time, increase its max size to 2000 characters. We do this
because with nested subgraphs, we hit the original 100 character limit
way too quickly.

We have to remove it from the primary key because primary keys are
limited to 767 bytes in MySQL.

langgraph/checkpoint/mysql/base.py

@@ -72,6 +72,24 @@
     "ALTER TABLE checkpoints MODIFY COLUMN `checkpoint_ns` VARCHAR(255) NOT NULL DEFAULT '';",
     "ALTER TABLE checkpoint_blobs MODIFY COLUMN `checkpoint_ns` VARCHAR(255) NOT NULL DEFAULT '';",
     "ALTER TABLE checkpoint_writes MODIFY COLUMN `checkpoint_ns` VARCHAR(255) NOT NULL DEFAULT '';",
+    """
+    ALTER TABLE checkpoints
+    DROP PRIMARY KEY,
+    ADD PRIMARY KEY (thread_id, checkpoint_id),
+    MODIFY COLUMN `checkpoint_ns` VARCHAR(2000) NOT NULL DEFAULT '';
+    """,
+    """
+    ALTER TABLE checkpoint_blobs
+    DROP PRIMARY KEY,
+    ADD PRIMARY KEY (thread_id, channel, version),
+    MODIFY COLUMN `checkpoint_ns` VARCHAR(2000) NOT NULL DEFAULT '';
+    """,
+    """
+    ALTER TABLE checkpoint_writes
+    DROP PRIMARY KEY,
+    ADD PRIMARY KEY (thread_id, checkpoint_id, task_id, idx),
+    MODIFY COLUMN `checkpoint_ns` VARCHAR(2000) NOT NULL DEFAULT '';
+    """,
 ]
 
 SELECT_SQL = f"""

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "langgraph-checkpoint-mysql"
-version = "2.0.8"
+version = "2.0.9"
 description = "Library with a MySQL implementation of LangGraph checkpoint saver."
 authors = ["Theodore Ni <[email protected]>"]
 license = "MIT"