1"""
 2This script's goal is to warn users about two situations that could lead to a diff:
 3
 4- They have blueprint models and some of their variables may be trimmed from `python_env`
 5- Variables are used in metadata-only contexts, e.g., within metadata-only macros
 6
 7Context:
 8
 9We used to store *all* blueprint variables in `python_env`, even though some of them were
10redundant. For example, if a blueprint variable is only used in the model's `name` property,
11then it is rendered once, at load time, and after that point it's not needed elsewhere.
12
13This behavior is now different: we only store the blueprint variables that are required to render
14expressions at runtime, such as model query or runtime-rendered properties, like `merge_filter`.
15
16Additionally, variables were previously treated as non-metadata, regardless of how they were used.
17This behavior changed as well: SQLMesh now analyzes variable references and tracks the data flow,
18in order to detect whether changing them will result in a metadata diff for a given model.
19
20Some examples where variables can be treated as metadata-only `python_env` executables are:
21
22- A variable is referenced in metadata-only macros
23- A variable is referenced in metadata-only expressions, such as virtual update statements
24- A variable is passed as argument to metadata-only macros
25"""
26
27import json
28
29from sqlglot import exp
30
31from sqlmesh.core.console import get_console
32
33SQLMESH_VARS = "__sqlmesh__vars__"
34SQLMESH_BLUEPRINT_VARS = "__sqlmesh__blueprint__vars__"
35METADATA_HASH_EXPRESSIONS = {"on_virtual_update", "audits", "signals", "audit_definitions"}
36
37
38def migrate_schemas(engine_adapter, schema, **kwargs):  # type: ignore
39    pass
40
41
42def migrate_rows(engine_adapter, schema, **kwargs):  # type: ignore
43    snapshots_table = "_snapshots"
44    if schema:
45        snapshots_table = f"{schema}.{snapshots_table}"
46
47    warning = (
48        "SQLMesh detected that it may not be able to fully migrate the state database. This should not impact "
49        "the migration process, but may result in unexpected changes being reported by the next `sqlmesh plan` "
50        "command. Please run `sqlmesh diff prod` after the migration has completed, before making any new "
51        "changes. If any unexpected changes are reported, consider running a forward-only plan to apply these "
52        "changes and avoid unnecessary backfills: sqlmesh plan prod --forward-only. "
53        "See https://sqlmesh.readthedocs.io/en/stable/concepts/plans/#forward-only-plans for more details.\n"
54    )
55
56    for (snapshot,) in engine_adapter.fetchall(
57        exp.select("snapshot").from_(snapshots_table), quote_identifiers=True
58    ):
59        parsed_snapshot = json.loads(snapshot)
60        node = parsed_snapshot["node"]
61
62        # Standalone audits don't have a data hash, so they're unaffected
63        if node.get("source_type") == "audit":
64            continue
65
66        python_env = node.get("python_env") or {}
67
68        if SQLMESH_BLUEPRINT_VARS in python_env or (
69            SQLMESH_VARS in python_env
70            and (
71                any(v.get("is_metadata") for v in python_env.values())
72                or any(node.get(k) for k in METADATA_HASH_EXPRESSIONS)
73            )
74        ):
75            get_console().log_warning(warning)
76            return