fastflowtransform.executors.postgres

PostgresExecutor

Bases: SqlIdentifierMixin, SnapshotSqlMixin, BaseExecutor[DataFrame]

Source code in src/fastflowtransform/executors/postgres.py

class PostgresExecutor(SqlIdentifierMixin, SnapshotSqlMixin, BaseExecutor[pd.DataFrame]):
    ENGINE_NAME = "postgres"
    _DEFAULT_PG_ROW_WIDTH = 128
    _BUDGET_GUARD = BudgetGuard(
        env_var="FF_PG_MAX_BYTES",
        estimator_attr="_estimate_query_bytes",
        engine_label="Postgres",
        what="query",
    )

    def __init__(self, dsn: str, schema: str | None = None):
        """
        Initialize Postgres executor.

        dsn     e.g.: postgresql+psycopg://user:pass@localhost:5432/dbname
        schema  default schema for reads/writes (also used for search_path)
        """
        if not dsn:
            raise ProfileConfigError(
                "Postgres DSN not set. Hint: profiles.yml → postgres.dsn or env FF_PG_DSN."
            )
        self.engine: Engine = create_engine(dsn, future=True)
        self.schema = schema

        if self.schema:
            try:
                with self.engine.begin() as conn:
                    conn.execute(text(f"CREATE SCHEMA IF NOT EXISTS {self._q_ident(self.schema)}"))
            except SQLAlchemyError as exc:
                raise ProfileConfigError(
                    f"Failed to ensure schema '{self.schema}' exists: {exc}"
                ) from exc

        # ⇣ fastflowtransform.testing expects executor.con.execute("SQL")
        self.con = SAConnShim(self.engine, schema=self.schema)

    def _execute_sql_core(
        self,
        sql: str,
        *args: Any,
        conn: Connection,
        **kwargs: Any,
    ) -> Any:
        """
        Lowest-level SQL executor:

        - sets search_path
        - executes the statement via given connection
        - NO budget guard
        - NO timing / stats

        Used by both the high-level _execute_sql and maintenance helpers.
        """
        self._set_search_path(conn)
        return conn.execute(text(sql), *args, **kwargs)

    def _execute_sql_maintenance(
        self,
        sql: str,
        *args: Any,
        conn: Connection | None = None,
        **kwargs: Any,
    ) -> Any:
        """
        Utility/maintenance SQL:

        - sets search_path
        - NO budget guard
        - NO stats

        Intended for:
          - utest cleanup
          - ANALYZE
          - DDL that shouldn't be budget-accounted
        """
        if conn is None:
            with self.engine.begin() as local_conn:
                return self._execute_sql_core(sql, *args, conn=local_conn, **kwargs)
        else:
            return self._execute_sql_core(sql, *args, conn=conn, **kwargs)

    def _execute_sql(
        self,
        sql: str,
        *args: Any,
        conn: Connection | None = None,
        **kwargs: Any,
    ) -> Any:
        """
        Central Postgres SQL runner.

        All model-driven SQL in this executor should go through here.

        If `conn` is provided, reuse that connection (important for temp tables /
        snapshots). Otherwise, open a fresh transaction via engine.begin().

        Also records simple per-query stats for run_results.json.
        """

        def _exec() -> Any:
            if conn is None:
                with self.engine.begin() as local_conn:
                    return self._execute_sql_core(sql, *args, conn=local_conn, **kwargs)
            return self._execute_sql_core(sql, *args, conn=conn, **kwargs)

        def _rows(result: Any) -> int | None:
            rc = getattr(result, "rowcount", None)
            if isinstance(rc, int) and rc >= 0:
                return rc
            return None

        return run_sql_with_budget(
            self,
            sql,
            guard=self._BUDGET_GUARD,
            exec_fn=_exec,
            rowcount_extractor=_rows,
            estimate_fn=self._estimate_query_bytes,
        )

    def _analyze_relations(
        self,
        relations: Iterable[str],
        conn: Connection | None = None,
    ) -> None:
        """
        Run ANALYZE on the given relations.

        - Never goes through _execute_sql (avoids the budget guard recursion).
        - Uses passed-in conn if given, otherwise opens its own transaction.
        - Best-effort: logs and continues on failure.
        """
        owns_conn = False
        if conn is None:
            conn_ctx = self.engine.begin()
            conn = conn_ctx.__enter__()
            owns_conn = True
        try:
            self._set_search_path(conn)
            for rel in relations:
                try:
                    # If it already looks qualified, leave it; otherwise qualify.
                    qrel = self._qualified(rel) if "." not in rel else rel
                    conn.execute(text(f"ANALYZE {qrel}"))
                except Exception:
                    pass
        finally:
            if owns_conn:
                conn_ctx.__exit__(None, None, None)

    # --- Cost estimation for the shared BudgetGuard -----------------

    def _estimate_query_bytes(self, sql: str) -> int | None:
        """
        Best-effort bytes estimate for a SELECT-ish query using
        EXPLAIN (FORMAT JSON).

        Approximation: estimated_rows * avg_row_width (in bytes).
        Returns None if:
          - the query is not SELECT/CTE
          - EXPLAIN fails
          - the JSON structure is not what we expect
        """
        body = self._extract_select_like(sql)
        lower = body.lstrip().lower()
        if not lower.startswith(("select", "with")):
            # Only try to estimate for read-like queries
            return None

        explain_sql = f"EXPLAIN (FORMAT JSON) {body}"

        try:
            with self.engine.begin() as conn:
                self._set_search_path(conn)
                raw = conn.execute(text(explain_sql)).scalar()
        except Exception:
            return None

        if raw is None:
            return None

        try:
            data = json.loads(raw)
        except Exception:
            data = raw

        # Postgres JSON format: list with a single object
        if isinstance(data, list) and data:
            root = data[0]
        elif isinstance(data, dict):
            root = data
        else:
            return None

        plan = root.get("Plan")
        if not isinstance(plan, dict):
            if isinstance(root, dict) and "Node Type" in root:
                plan = root
            else:
                return None

        return self._estimate_bytes_from_plan(plan)

    def _estimate_bytes_from_plan(self, plan: dict[str, Any]) -> int | None:
        """
        Estimate bytes for the *model output* from the root plan node.

        Approximation: root.Plan Rows * root.Plan Width (or DEFAULT_PG_ROW_WIDTH
        if width is missing).
        """

        def _to_int(node: dict[str, Any], keys: tuple[str, ...]) -> int | None:
            for key in keys:
                val = node.get(key)
                if val is None:
                    continue
                try:
                    return int(val)
                except (TypeError, ValueError):
                    continue
            return None

        rows = _to_int(plan, ("Plan Rows", "Plan_Rows", "Rows"))
        width = _to_int(plan, ("Plan Width", "Plan_Width", "Width"))

        if rows is None and width is None:
            return None

        candidate: int | None

        if rows is not None and width is not None:
            candidate = rows * width
        elif rows is not None:
            candidate = rows * self._DEFAULT_PG_ROW_WIDTH
        else:
            candidate = width

        if candidate is None or candidate <= 0:
            return None

        return int(candidate)

    # --- Helpers ---------------------------------------------------------
    def _q_ident(self, ident: str) -> str:
        # Simple, safe quoting for identifiers
        return '"' + ident.replace('"', '""') + '"'

    def _quote_identifier(self, ident: str) -> str:
        return self._q_ident(ident)

    def _qualified(self, relname: str, schema: str | None = None) -> str:
        return self._qualify_identifier(relname, schema=schema)

    def _set_search_path(self, conn: Connection | SAConnShim) -> None:
        if self.schema:
            conn.execute(text(f"SET LOCAL search_path = {self._q_ident(self.schema)}"))

    def _extract_select_like(self, sql_or_body: str) -> str:
        """
        Normalize a SELECT/CTE body:
        - Accept full statements and strip everything before the first WITH/SELECT.
        - Strip trailing semicolons/whitespace.
        """
        s = (sql_or_body or "").lstrip()
        lower = s.lower()
        pos_with = lower.find("with")
        pos_select = lower.find("select")
        if pos_with == -1 and pos_select == -1:
            return s.rstrip(";\n\t ")
        start = min([p for p in (pos_with, pos_select) if p != -1])
        return s[start:].rstrip(";\n\t ")

    # ---------- IO ----------
    def _read_relation(self, relation: str, node: Node, deps: Iterable[str]) -> pd.DataFrame:
        qualified = self._qualified(relation)
        try:
            with self.engine.begin() as conn:
                if self.schema:
                    conn.execute(text(f'SET LOCAL search_path = "{self.schema}"'))
                return pd.read_sql_query(text(f"select * from {qualified}"), conn)
        except ProgrammingError as e:
            raise e

    def _materialize_relation(self, relation: str, df: pd.DataFrame, node: Node) -> None:
        self._write_dataframe_with_stats(relation, df, node)

    def _write_dataframe_with_stats(self, relation: str, df: pd.DataFrame, node: Node) -> None:
        start = perf_counter()
        try:
            df.to_sql(
                relation,
                self.engine,
                if_exists="replace",
                index=False,
                schema=self.schema,
                method="multi",
            )
        except SQLAlchemyError as e:
            raise ModelExecutionError(
                node_name=node.name, relation=self._qualified(relation), message=str(e)
            ) from e
        else:
            self._analyze_relations([relation])
            self._record_dataframe_stats(df, int((perf_counter() - start) * 1000))

    def _record_dataframe_stats(self, df: pd.DataFrame, duration_ms: int) -> None:
        rows = len(df)
        bytes_estimate = int(df.memory_usage(deep=True).sum()) if rows > 0 else 0
        bytes_val = bytes_estimate if bytes_estimate > 0 else None
        self._record_query_stats(
            QueryStats(
                bytes_processed=bytes_val,
                rows=rows if rows > 0 else None,
                duration_ms=duration_ms,
            )
        )

    # ---------- Python view helper ----------
    def _create_or_replace_view_from_table(
        self, view_name: str, backing_table: str, node: Node
    ) -> None:
        q_view = self._qualified(view_name)
        q_back = self._qualified(backing_table)
        try:
            with self.engine.begin() as conn:
                self._execute_sql(f"DROP VIEW IF EXISTS {q_view} CASCADE", conn=conn)
                self._execute_sql(
                    f"CREATE OR REPLACE VIEW {q_view} AS SELECT * FROM {q_back}", conn=conn
                )

        except Exception as e:
            raise ModelExecutionError(node.name, q_view, str(e)) from e

    def _frame_name(self) -> str:
        return "pandas"

    def _create_or_replace_view(self, target_sql: str, select_body: str, node: Node) -> None:
        try:
            self._execute_sql(f"DROP VIEW IF EXISTS {target_sql} CASCADE")
            self._execute_sql(f"CREATE OR REPLACE VIEW {target_sql} AS {select_body}")
        except Exception as e:
            preview = f"-- target={target_sql}\n{select_body}"
            raise ModelExecutionError(node.name, target_sql, str(e), sql_snippet=preview) from e

    def _create_or_replace_table(self, target_sql: str, select_body: str, node: Node) -> None:
        """
        Postgres does NOT support 'CREATE OR REPLACE TABLE'.
        Use DROP TABLE IF EXISTS + CREATE TABLE AS, and accept CTE bodies.
        """
        try:
            self._execute_sql(f"DROP TABLE IF EXISTS {target_sql} CASCADE")
            self._execute_sql(f"CREATE TABLE {target_sql} AS {select_body}")
            self._analyze_relations([target_sql])
        except Exception as e:
            preview = f"-- target={target_sql}\n{select_body}"
            raise ModelExecutionError(node.name, target_sql, str(e), sql_snippet=preview) from e

    # ---------- meta ----------
    def on_node_built(self, node: Node, relation: str, fingerprint: str) -> None:
        """
        Write/update _ff_meta in the current schema after a successful build.
        """
        ensure_meta_table(self)
        upsert_meta(self, node.name, relation, fingerprint, "postgres")

    # ── Incremental API ────────────────────────────────────────────────────
    def exists_relation(self, relation: str) -> bool:
        """
        Return True if a table OR view exists for 'relation' in current schema.
        """
        sql = """
            select 1
            from information_schema.tables
            where table_schema = current_schema()
              and lower(table_name) = lower(:t)
            union all
            select 1
            from information_schema.views
            where table_schema = current_schema()
              and lower(table_name) = lower(:t)
            limit 1
            """

        return bool(self._execute_sql(sql, {"t": relation}).fetchone())

    def create_table_as(self, relation: str, select_sql: str) -> None:
        body = self._extract_select_like(select_sql)
        qrel = self._qualified(relation)
        self._execute_sql(f"create table {qrel} as {body}")
        self._analyze_relations([relation])

    def full_refresh_table(self, relation: str, select_sql: str) -> None:
        """
        Full refresh for incremental fallbacks:
        DROP TABLE IF EXISTS + CREATE TABLE AS.
        """
        body = self._selectable_body(select_sql).strip().rstrip(";\n\t ")
        qrel = self._qualified(relation)
        self._execute_sql(f"drop table if exists {qrel}")
        self._execute_sql(f"create table {qrel} as {body}")
        self._analyze_relations([relation])

    def incremental_insert(self, relation: str, select_sql: str) -> None:
        body = self._extract_select_like(select_sql)
        qrel = self._qualified(relation)
        self._execute_sql(f"insert into {qrel} {body}")
        self._analyze_relations([relation])

    def incremental_merge(self, relation: str, select_sql: str, unique_key: list[str]) -> None:
        """
        Portable fallback: staging + delete + insert.
        """
        body = self._extract_select_like(select_sql)
        qrel = self._qualified(relation)
        pred = " AND ".join([f"t.{k}=s.{k}" for k in unique_key])
        self._execute_sql(f"create temporary table ff_stg as {body}")
        try:
            self._execute_sql(f"delete from {qrel} t using ff_stg s where {pred}")
            self._execute_sql(f"insert into {qrel} select * from ff_stg")
            self._analyze_relations([relation])
        finally:
            self._execute_sql("drop table if exists ff_stg")

    def alter_table_sync_schema(
        self, relation: str, select_sql: str, *, mode: str = "append_new_columns"
    ) -> None:
        """
        Add new columns present in SELECT but missing on target (as text).
        """
        body = self._extract_select_like(select_sql)
        qrel = self._qualified(relation)

        with self.engine.begin() as conn:
            # Probe output columns
            cols = [r[0] for r in self._execute_sql(f"select * from ({body}) q limit 0")]

            # Existing columns in target table
            existing = {
                r[0]
                for r in self._execute_sql(
                    """
                    select column_name
                    from information_schema.columns
                    where table_schema = current_schema()
                    and lower(table_name)=lower(:t)
                    """,
                    {"t": relation},
                ).fetchall()
            }

            add = [c for c in cols if c not in existing]
            for c in add:
                self._execute_sql(f'alter table {qrel} add column "{c}" text', conn=conn)

    # ── Snapshot API ──────────────────────────────────────────────────────
    def _snapshot_target_identifier(self, rel_name: str) -> str:
        return self._qualified(rel_name)

    def _snapshot_current_timestamp(self) -> str:
        return "current_timestamp"

    def _snapshot_null_timestamp(self) -> str:
        return "cast(null as timestamp)"

    def _snapshot_null_hash(self) -> str:
        return "cast(null as text)"

    def _snapshot_hash_expr(self, check_cols: list[str], src_alias: str) -> str:
        concat_expr = self._snapshot_concat_expr(check_cols, src_alias)
        return f"md5({concat_expr})"

    def _snapshot_cast_as_string(self, expr: str) -> str:
        return f"cast({expr} as text)"

    def _snapshot_source_ref(
        self, rel_name: str, select_body: str
    ) -> tuple[str, Callable[[], None]]:
        src_name = f"__ff_snapshot_src_{rel_name}".replace(".", "_")
        src_q = self._q_ident(src_name)
        self._execute_sql(f"drop table if exists {src_q}")
        self._execute_sql(f"create temporary table {src_q} as {select_body}")

        def _cleanup() -> None:
            self._execute_sql(f"drop table if exists {src_q}")

        return src_q, _cleanup

    def execute_hook_sql(self, sql: str) -> None:
        """
        Execute one or multiple SQL statements for pre/post/on_run hooks.

        Accepts a string that may contain ';'-separated statements.
        """
        self._execute_sql(sql)

    # ---- Unit-test helpers -------------------------------------------------

    def utest_load_relation_from_rows(self, relation: str, rows: list[dict]) -> None:
        """
        Load rows into a Postgres table for unit tests (replace if exists),
        without using pandas.to_sql.
        """
        qualified = self._qualified(relation)

        if not rows:
            # Ensure an empty table exists (corner case).
            try:
                with self.engine.begin() as conn:
                    self._execute_sql_maintenance(
                        f"DROP TABLE IF EXISTS {qualified} CASCADE",
                        conn=conn,
                    )
                    self._execute_sql_maintenance(
                        f"CREATE TABLE {qualified} ()",
                        conn=conn,
                    )
            except SQLAlchemyError as e:
                raise ModelExecutionError(
                    node_name=f"utest::{relation}",
                    relation=self._qualified(relation),
                    message=str(e),
                ) from e
            return

        first = rows[0]
        if not isinstance(first, dict):
            raise ModelExecutionError(
                node_name=f"utest::{relation}",
                relation=self._qualified(relation),
                message=f"Expected list[dict] for rows, got {type(first).__name__}",
            )

        cols = list(first.keys())
        col_list_sql = ", ".join(self._q_ident(c) for c in cols)
        select_exprs = ", ".join(f":{c} AS {self._q_ident(c)}" for c in cols)
        insert_values_sql = ", ".join(f":{c}" for c in cols)

        try:
            with self.engine.begin() as conn:
                # Replace any existing table
                self._execute_sql_maintenance(
                    f"DROP TABLE IF EXISTS {qualified} CASCADE",
                    conn=conn,
                )

                # Create table from first row
                create_sql = f"CREATE TABLE {qualified} AS SELECT {select_exprs}"
                self._execute_sql_maintenance(create_sql, first, conn=conn)

                # Insert remaining rows
                if len(rows) > 1:
                    insert_sql = (
                        f"INSERT INTO {qualified} ({col_list_sql}) VALUES ({insert_values_sql})"
                    )
                    for row in rows[1:]:
                        self._execute_sql_maintenance(insert_sql, row, conn=conn)

        except SQLAlchemyError as e:
            raise ModelExecutionError(
                node_name=f"utest::{relation}",
                relation=self._qualified(relation),
                message=str(e),
            ) from e

    def utest_read_relation(self, relation: str) -> pd.DataFrame:
        """
        Read a relation as a DataFrame for unit-test assertions.
        """
        qualified = self._qualified(relation)
        with self.engine.begin() as conn:
            self._set_search_path(conn)
            return pd.read_sql_query(text(f"select * from {qualified}"), conn)

    def utest_clean_target(self, relation: str) -> None:
        """
        For unit tests: drop any view or table with this name in the configured schema.

        We avoid WrongObjectType by:
          - querying information_schema for existing table/view with this name
          - dropping only the matching kinds.
        """
        with self.engine.begin() as conn:
            # Use the same search_path logic as the rest of the executor
            self._set_search_path(conn)

            # Decide which schema to inspect
            cur_schema = conn.execute(text("select current_schema()")).scalar()
            schema = self.schema or cur_schema

            # Find objects named <relation> in that schema
            info_sql = """
                select kind, table_schema, table_name from (
                  select 'table' as kind, table_schema, table_name
                  from information_schema.tables
                  where lower(table_schema) = lower(:schema)
                    and lower(table_name) = lower(:rel)
                  union all
                  select 'view' as kind, table_schema, table_name
                  from information_schema.views
                  where lower(table_schema) = lower(:schema)
                    and lower(table_name) = lower(:rel)
                ) s
                order by kind;
            """
            rows = conn.execute(
                text(info_sql),
                {"schema": schema, "rel": relation},
            ).fetchall()

            for kind, table_schema, table_name in rows:
                qualified = f'"{table_schema}"."{table_name}"'
                if kind == "view":
                    conn.execute(text(f"DROP VIEW IF EXISTS {qualified} CASCADE"))
                else:  # table
                    conn.execute(text(f"DROP TABLE IF EXISTS {qualified} CASCADE"))

on_node_built

on_node_built(node, relation, fingerprint)

Write/update _ff_meta in the current schema after a successful build.

Source code in src/fastflowtransform/executors/postgres.py

def on_node_built(self, node: Node, relation: str, fingerprint: str) -> None:
    """
    Write/update _ff_meta in the current schema after a successful build.
    """
    ensure_meta_table(self)
    upsert_meta(self, node.name, relation, fingerprint, "postgres")

exists_relation

exists_relation(relation)

Return True if a table OR view exists for 'relation' in current schema.

Source code in src/fastflowtransform/executors/postgres.py

def exists_relation(self, relation: str) -> bool:
    """
    Return True if a table OR view exists for 'relation' in current schema.
    """
    sql = """
        select 1
        from information_schema.tables
        where table_schema = current_schema()
          and lower(table_name) = lower(:t)
        union all
        select 1
        from information_schema.views
        where table_schema = current_schema()
          and lower(table_name) = lower(:t)
        limit 1
        """

    return bool(self._execute_sql(sql, {"t": relation}).fetchone())

full_refresh_table

full_refresh_table(relation, select_sql)

Full refresh for incremental fallbacks: DROP TABLE IF EXISTS + CREATE TABLE AS.

Source code in src/fastflowtransform/executors/postgres.py

def full_refresh_table(self, relation: str, select_sql: str) -> None:
    """
    Full refresh for incremental fallbacks:
    DROP TABLE IF EXISTS + CREATE TABLE AS.
    """
    body = self._selectable_body(select_sql).strip().rstrip(";\n\t ")
    qrel = self._qualified(relation)
    self._execute_sql(f"drop table if exists {qrel}")
    self._execute_sql(f"create table {qrel} as {body}")
    self._analyze_relations([relation])

incremental_merge

incremental_merge(relation, select_sql, unique_key)

Portable fallback: staging + delete + insert.

Source code in src/fastflowtransform/executors/postgres.py

def incremental_merge(self, relation: str, select_sql: str, unique_key: list[str]) -> None:
    """
    Portable fallback: staging + delete + insert.
    """
    body = self._extract_select_like(select_sql)
    qrel = self._qualified(relation)
    pred = " AND ".join([f"t.{k}=s.{k}" for k in unique_key])
    self._execute_sql(f"create temporary table ff_stg as {body}")
    try:
        self._execute_sql(f"delete from {qrel} t using ff_stg s where {pred}")
        self._execute_sql(f"insert into {qrel} select * from ff_stg")
        self._analyze_relations([relation])
    finally:
        self._execute_sql("drop table if exists ff_stg")

alter_table_sync_schema

alter_table_sync_schema(relation, select_sql, *, mode='append_new_columns')

Add new columns present in SELECT but missing on target (as text).

Source code in src/fastflowtransform/executors/postgres.py

def alter_table_sync_schema(
    self, relation: str, select_sql: str, *, mode: str = "append_new_columns"
) -> None:
    """
    Add new columns present in SELECT but missing on target (as text).
    """
    body = self._extract_select_like(select_sql)
    qrel = self._qualified(relation)

    with self.engine.begin() as conn:
        # Probe output columns
        cols = [r[0] for r in self._execute_sql(f"select * from ({body}) q limit 0")]

        # Existing columns in target table
        existing = {
            r[0]
            for r in self._execute_sql(
                """
                select column_name
                from information_schema.columns
                where table_schema = current_schema()
                and lower(table_name)=lower(:t)
                """,
                {"t": relation},
            ).fetchall()
        }

        add = [c for c in cols if c not in existing]
        for c in add:
            self._execute_sql(f'alter table {qrel} add column "{c}" text', conn=conn)

execute_hook_sql

execute_hook_sql(sql)

Execute one or multiple SQL statements for pre/post/on_run hooks.

Accepts a string that may contain ';'-separated statements.

Source code in src/fastflowtransform/executors/postgres.py

def execute_hook_sql(self, sql: str) -> None:
    """
    Execute one or multiple SQL statements for pre/post/on_run hooks.

    Accepts a string that may contain ';'-separated statements.
    """
    self._execute_sql(sql)

utest_load_relation_from_rows

utest_load_relation_from_rows(relation, rows)

Load rows into a Postgres table for unit tests (replace if exists), without using pandas.to_sql.

Source code in src/fastflowtransform/executors/postgres.py

def utest_load_relation_from_rows(self, relation: str, rows: list[dict]) -> None:
    """
    Load rows into a Postgres table for unit tests (replace if exists),
    without using pandas.to_sql.
    """
    qualified = self._qualified(relation)

    if not rows:
        # Ensure an empty table exists (corner case).
        try:
            with self.engine.begin() as conn:
                self._execute_sql_maintenance(
                    f"DROP TABLE IF EXISTS {qualified} CASCADE",
                    conn=conn,
                )
                self._execute_sql_maintenance(
                    f"CREATE TABLE {qualified} ()",
                    conn=conn,
                )
        except SQLAlchemyError as e:
            raise ModelExecutionError(
                node_name=f"utest::{relation}",
                relation=self._qualified(relation),
                message=str(e),
            ) from e
        return

    first = rows[0]
    if not isinstance(first, dict):
        raise ModelExecutionError(
            node_name=f"utest::{relation}",
            relation=self._qualified(relation),
            message=f"Expected list[dict] for rows, got {type(first).__name__}",
        )

    cols = list(first.keys())
    col_list_sql = ", ".join(self._q_ident(c) for c in cols)
    select_exprs = ", ".join(f":{c} AS {self._q_ident(c)}" for c in cols)
    insert_values_sql = ", ".join(f":{c}" for c in cols)

    try:
        with self.engine.begin() as conn:
            # Replace any existing table
            self._execute_sql_maintenance(
                f"DROP TABLE IF EXISTS {qualified} CASCADE",
                conn=conn,
            )

            # Create table from first row
            create_sql = f"CREATE TABLE {qualified} AS SELECT {select_exprs}"
            self._execute_sql_maintenance(create_sql, first, conn=conn)

            # Insert remaining rows
            if len(rows) > 1:
                insert_sql = (
                    f"INSERT INTO {qualified} ({col_list_sql}) VALUES ({insert_values_sql})"
                )
                for row in rows[1:]:
                    self._execute_sql_maintenance(insert_sql, row, conn=conn)

    except SQLAlchemyError as e:
        raise ModelExecutionError(
            node_name=f"utest::{relation}",
            relation=self._qualified(relation),
            message=str(e),
        ) from e

utest_read_relation

utest_read_relation(relation)

Read a relation as a DataFrame for unit-test assertions.

Source code in src/fastflowtransform/executors/postgres.py

def utest_read_relation(self, relation: str) -> pd.DataFrame:
    """
    Read a relation as a DataFrame for unit-test assertions.
    """
    qualified = self._qualified(relation)
    with self.engine.begin() as conn:
        self._set_search_path(conn)
        return pd.read_sql_query(text(f"select * from {qualified}"), conn)

utest_clean_target

utest_clean_target(relation)

For unit tests: drop any view or table with this name in the configured schema.

We avoid WrongObjectType by

• querying information_schema for existing table/view with this name
• dropping only the matching kinds.

Source code in src/fastflowtransform/executors/postgres.py

def utest_clean_target(self, relation: str) -> None:
    """
    For unit tests: drop any view or table with this name in the configured schema.

    We avoid WrongObjectType by:
      - querying information_schema for existing table/view with this name
      - dropping only the matching kinds.
    """
    with self.engine.begin() as conn:
        # Use the same search_path logic as the rest of the executor
        self._set_search_path(conn)

        # Decide which schema to inspect
        cur_schema = conn.execute(text("select current_schema()")).scalar()
        schema = self.schema or cur_schema

        # Find objects named <relation> in that schema
        info_sql = """
            select kind, table_schema, table_name from (
              select 'table' as kind, table_schema, table_name
              from information_schema.tables
              where lower(table_schema) = lower(:schema)
                and lower(table_name) = lower(:rel)
              union all
              select 'view' as kind, table_schema, table_name
              from information_schema.views
              where lower(table_schema) = lower(:schema)
                and lower(table_name) = lower(:rel)
            ) s
            order by kind;
        """
        rows = conn.execute(
            text(info_sql),
            {"schema": schema, "rel": relation},
        ).fetchall()

        for kind, table_schema, table_name in rows:
            qualified = f'"{table_schema}"."{table_name}"'
            if kind == "view":
                conn.execute(text(f"DROP VIEW IF EXISTS {qualified} CASCADE"))
            else:  # table
                conn.execute(text(f"DROP TABLE IF EXISTS {qualified} CASCADE"))

run_sql

run_sql(node, env)

Orchestrate SQL models

1) Render Jinja (ref/source/this) and strip leading {{ config(...) }}. 2) If the SQL is full DDL (CREATE …), execute it verbatim (passthrough). 3) Otherwise, normalize to CREATE OR REPLACE {TABLE|VIEW} AS . The body is CTE-aware (keeps WITH … SELECT … intact).

On failure, raise ModelExecutionError with a helpful snippet.

Source code in src/fastflowtransform/executors/base.py

def run_sql(self, node: Node, env: Environment) -> None:
    """
    Orchestrate SQL models:
      1) Render Jinja (ref/source/this) and strip leading {{ config(...) }}.
      2) If the SQL is full DDL (CREATE …), execute it verbatim (passthrough).
      3) Otherwise, normalize to CREATE OR REPLACE {TABLE|VIEW} AS <body>.
         The body is CTE-aware (keeps WITH … SELECT … intact).
    On failure, raise ModelExecutionError with a helpful snippet.
    """
    meta = getattr(node, "meta", {}) or {}
    if self._meta_is_incremental(meta):
        # Delegates to incremental engine: render, schema sync, merge/insert, etc.
        return _ff_incremental.run_or_dispatch(self, node, env)

    if self._meta_is_snapshot(meta):
        # Snapshots are executed via the dedicated CLI: `fft snapshot run`.
        raise ModelExecutionError(
            node_name=node.name,
            relation=relation_for(node.name),
            message=(
                "Snapshot models cannot be executed via 'fft run'. "
                "Use 'fft snapshot run' instead."
            ),
            sql_snippet="",
        )

    sql_rendered = self.render_sql(
        node,
        env,
        ref_resolver=lambda name: self._resolve_ref(name, env),
        source_resolver=self._resolve_source,
    )
    sql = self._strip_leading_config(sql_rendered).strip()

    materialization = (node.meta or {}).get("materialized", "table")
    if materialization == "ephemeral":
        return

    # 1) Direct DDL passthrough (CREATE [OR REPLACE] {TABLE|VIEW} …)
    if self._looks_like_direct_ddl(sql):
        try:
            self._execute_sql_direct(sql, node)
            return
        except NotImplementedError:
            # Engine doesn't implement direct DDL → fall back to normalized materialization.
            pass
        except Exception as e:
            raise ModelExecutionError(
                node_name=node.name,
                relation=relation_for(node.name),
                message=str(e),
                sql_snippet=sql,
            ) from e

    # 2) Normalized materialization path (CTE-safe body)
    body = self._selectable_body(sql).rstrip(" ;\n\t")
    target_sql = self._format_relation_for_ref(node.name)

    # Centralized SQL preview logging (applies to ALL engines)
    preview = (
        f"=== MATERIALIZE ===\n"
        f"-- model: {node.name}\n"
        f"-- materialized: {materialization}\n"
        f"-- target: {target_sql}\n"
        f"{body}\n"
    )
    echo_debug(preview)

    try:
        self._apply_sql_materialization(node, target_sql, body, materialization)
    except Exception as e:
        preview = f"-- materialized={materialization}\n-- target={target_sql}\n{body}"
        raise ModelExecutionError(
            node_name=node.name,
            relation=relation_for(node.name),
            message=str(e),
            sql_snippet=preview,
        ) from e

configure_query_budget_limit

configure_query_budget_limit(limit)

Inject a configured per-query byte limit (e.g. from budgets.yml).

Source code in src/fastflowtransform/executors/base.py

def configure_query_budget_limit(self, limit: int | None) -> None:
    """
    Inject a configured per-query byte limit (e.g. from budgets.yml).
    """
    if limit is None:
        self._ff_configured_query_limit = None
        return
    try:
        iv = int(limit)
    except Exception:
        self._ff_configured_query_limit = None
        return
    self._ff_configured_query_limit = iv if iv > 0 else None

reset_node_stats

reset_node_stats()

Reset per-node statistics buffer.

The run engine calls this before executing a model so that all stats recorded via _record_query_stats(...) belong to that node.

Source code in src/fastflowtransform/executors/base.py

def reset_node_stats(self) -> None:
    """
    Reset per-node statistics buffer.

    The run engine calls this before executing a model so that all
    stats recorded via `_record_query_stats(...)` belong to that node.
    """
    # just clear the buffer; next recording will re-create it
    self._ff_query_stats_buffer = []

get_node_stats

get_node_stats()

Aggregate buffered QueryStats into a simple dict:

{
  "bytes_scanned": <sum>,
  "rows": <sum>,
  "query_duration_ms": <sum>,
}

Called by the run engine after a node finishes.

Source code in src/fastflowtransform/executors/base.py

def get_node_stats(self) -> dict[str, int]:
    """
    Aggregate buffered QueryStats into a simple dict:

        {
          "bytes_scanned": <sum>,
          "rows": <sum>,
          "query_duration_ms": <sum>,
        }

    Called by the run engine after a node finishes.
    """
    stats_list = self._drain_query_stats()
    if not stats_list:
        return {}

    total_bytes = 0
    total_rows = 0
    total_duration = 0

    for s in stats_list:
        if s.bytes_processed is not None:
            total_bytes += int(s.bytes_processed)
        if s.rows is not None:
            total_rows += int(s.rows)
        if s.duration_ms is not None:
            total_duration += int(s.duration_ms)

    return {
        "bytes_scanned": total_bytes,
        "rows": total_rows,
        "query_duration_ms": total_duration,
    }

run_python

run_python(node)

Execute the Python model for a given node and materialize its result.

Source code in src/fastflowtransform/executors/base.py

def run_python(self, node: Node) -> None:
    """Execute the Python model for a given node and materialize its result."""
    func = REGISTRY.py_funcs[node.name]
    deps = REGISTRY.nodes[node.name].deps or []

    self._reset_http_ctx(node)

    # arg = self._build_python_args(node, deps)
    args, argmap = self._build_python_inputs(node, deps)
    requires = REGISTRY.py_requires.get(node.name, {})
    # if deps:
    #     self._validate_required(node.name, arg, requires)
    if deps:
        # Required-columns check works against the mapping
        self._validate_required(node.name, argmap, requires)

    # out = self._execute_python_func(func, arg, node)
    out = self._execute_python_func(func, args, node)

    target = relation_for(node.name)
    meta = getattr(node, "meta", {}) or {}
    mat = self._resolve_materialization_strategy(meta)

    if mat == "incremental":
        self._materialize_incremental(target, out, node, meta)
    elif mat == "view":
        self._materialize_view(target, out, node)
    else:
        self._materialize_relation(target, out, node)

    self._snapshot_http_ctx(node)

snapshot_prune

snapshot_prune(relation, unique_key, keep_last, *, dry_run=False)

Delete older snapshot versions while keeping the most recent keep_last rows per business key (including the current row).

Source code in src/fastflowtransform/executors/_snapshot_sql_mixin.py

    def snapshot_prune(
        self,
        relation: str,
        unique_key: list[str],
        keep_last: int,
        *,
        dry_run: bool = False,
    ) -> None:
        """
        Delete older snapshot versions while keeping the most recent `keep_last`
        rows per business key (including the current row).
        """
        ex = cast("BaseExecutor[Any]", self)

        if keep_last <= 0:
            return

        keys = [k for k in unique_key if k]
        if not keys:
            return

        target = self._snapshot_target_identifier(relation)
        vf = self.SNAPSHOT_VALID_FROM_COL  # type: ignore[attr-defined]

        key_select = ", ".join(keys)
        part_by = ", ".join(keys)

        ranked_sql = f"""
SELECT
  {key_select},
  {vf},
  ROW_NUMBER() OVER (
    PARTITION BY {part_by}
    ORDER BY {vf} DESC
  ) AS rn
FROM {target}
"""

        if dry_run:
            sql = f"""
WITH ranked AS (
  {ranked_sql}
)
SELECT COUNT(*) AS rows_to_delete
FROM ranked
WHERE rn > {int(keep_last)}
"""
            res = ex._execute_sql(sql)
            count = self._snapshot_fetch_count(res)
            echo(
                f"[DRY-RUN] snapshot_prune({relation}): would delete {count} row(s) "
                f"(keep_last={keep_last})"
            )
            return

        join_pred = " AND ".join([f"t.{k} = r.{k}" for k in keys])
        delete_sql = f"""
DELETE FROM {target} t
USING (
  {ranked_sql}
) r
WHERE
  r.rn > {int(keep_last)}
  AND {join_pred}
  AND t.{vf} = r.{vf}
"""
        ex._execute_sql(delete_sql)