diff --git a/sqlmesh/migrations/v0064_join_when_matched_strings.py b/sqlmesh/migrations/v0064_join_when_matched_strings.py
new file mode 100644
index 000000000..324f6837a
--- /dev/null
+++ b/sqlmesh/migrations/v0064_join_when_matched_strings.py
@@ -0,0 +1,86 @@
+"""Join list of `WHEN [NOT] MATCHED` strings into a single string."""
+
+import json
+
+import pandas as pd
+from sqlglot import exp
+
+from sqlmesh.utils.migration import index_text_type, blob_text_type
+
+
+def migrate(state_sync, **kwargs):  # type: ignore
+    engine_adapter = state_sync.engine_adapter
+    schema = state_sync.schema
+    snapshots_table = "_snapshots"
+    index_type = index_text_type(engine_adapter.dialect)
+    if schema:
+        snapshots_table = f"{schema}.{snapshots_table}"
+
+    new_snapshots = []
+
+    for (
+        name,
+        identifier,
+        version,
+        snapshot,
+        kind_name,
+        updated_ts,
+        unpaused_ts,
+        ttl_ms,
+        unrestorable,
+    ) in engine_adapter.fetchall(
+        exp.select(
+            "name",
+            "identifier",
+            "version",
+            "snapshot",
+            "kind_name",
+            "updated_ts",
+            "unpaused_ts",
+            "ttl_ms",
+            "unrestorable",
+        ).from_(snapshots_table),
+        quote_identifiers=True,
+    ):
+        parsed_snapshot = json.loads(snapshot)
+        node = parsed_snapshot["node"]
+        parsed_snapshot = json.loads(snapshot)
+
+        if "kind" in node:
+            kind = node["kind"]
+            if isinstance(when_matched := kind.get("when_matched"), list):
+                kind["when_matched"] = " ".join(when_matched)
+
+            new_snapshots.append(
+                {
+                    "name": name,
+                    "identifier": identifier,
+                    "version": version,
+                    "snapshot": json.dumps(parsed_snapshot),
+                    "kind_name": kind_name,
+                    "updated_ts": updated_ts,
+                    "unpaused_ts": unpaused_ts,
+                    "ttl_ms": ttl_ms,
+                    "unrestorable": unrestorable,
+                }
+            )
+
+    if new_snapshots:
+        engine_adapter.delete_from(snapshots_table, "TRUE")
+        blob_type = blob_text_type(engine_adapter.dialect)
+
+        engine_adapter.insert_append(
+            snapshots_table,
+            pd.DataFrame(new_snapshots),
+            columns_to_types={
+                "name": exp.DataType.build(index_type),
+                "identifier": exp.DataType.build(index_type),
+                "version": exp.DataType.build(index_type),
+                "snapshot": exp.DataType.build(blob_type),
+                "kind_name": exp.DataType.build(index_type),
+                "updated_ts": exp.DataType.build("bigint"),
+                "unpaused_ts": exp.DataType.build("bigint"),
+                "ttl_ms": exp.DataType.build("bigint"),
+                "unrestorable": exp.DataType.build("boolean"),
+            },
+        )