Function write

python/pathway/io/postgres/__init__.py:605–893

Writes ``table`` to a Postgres table. Two types of output tables are supported: **stream of changes** and **snapshot**. When using **stream of changes**, the output table contains a log of all changes that occurred in the Pathway Live Data Framework table. In this case, it is expected t

(
    table: Table,
    postgres_settings: dict,
    table_name: str,
    *,
    schema_name: str | None = "public",
    max_batch_size: int | None = None,
    init_mode: Literal["default", "create_if_not_exists", "replace"] = "default",
    output_table_type: Literal["stream_of_changes", "snapshot"] = "stream_of_changes",
    primary_key: list[ColumnReference] | None = None,
    name: str | None = None,
    sort_by: Iterable[ColumnReference] | None = None,
    _external_diff_column: ColumnReference | None = None,
)

@check_arg_types
@trace_user_frame
def write(
    table: Table,
    postgres_settings: dict,
    table_name: str,
    *,
    schema_name: str | None = "public",
    max_batch_size: int | None = None,
    init_mode: Literal["default", "create_if_not_exists", "replace"] = "default",
    output_table_type: Literal["stream_of_changes", "snapshot"] = "stream_of_changes",
    primary_key: list[ColumnReference] | None = None,
    name: str | None = None,
    sort_by: Iterable[ColumnReference] | None = None,
    _external_diff_column: ColumnReference | None = None,
) -> None:
    """Writes ``table`` to a Postgres table. Two types of output tables are supported:
    **stream of changes** and **snapshot**.

    When using **stream of changes**, the output table contains a log of all changes that
    occurred in the Pathway Live Data Framework table. In this case, it is expected to have two additional columns,
    ``time`` and ``diff``, both of integer type. ``time`` indicates the transactional
    minibatch time in which the row change occurred. ``diff`` can be either ``1`` for
    row insertion or ``-1`` for row deletion.

    When using **snapshot**, the set of columns in the output table matches the set of
    columns in the table you are writing. No additional columns are created.

    Args:
        table: Table to be written.
        postgres_settings: Components for the connection string for Postgres. The string is
            formed by joining key-value pairs from the given dictionary with spaces,
            with each pair formatted as `key=value`. Keys must be strings. Values can be
            of any type; if a value is not a string, it will be converted using Python's
            `str()` function.
            The Pathway Live Data Framework injects conservative TCP-keepalive defaults (``keepalives``,
            ``keepalives_idle=300``, ``keepalives_interval=30``, ``keepalives_count=3``,
            and ``tcp_user_timeout=300000``) so that an unreachable
            the Pathway Live Data Framework process is detected by PostgreSQL within minutes rather than
            the OS-inherited ~2-hour default; any of these can be overridden by
            passing the same key in ``postgres_settings``.
        table_name: Name of the target table. Any PostgreSQL identifier is
            accepted — the connector quotes the name before interpolating it
            into generated SQL, so hyphens, mixed case, and reserved words
            round-trip as-is. Column names in ``table`` and in ``primary_key``
            are quoted the same way.
        schema_name: Name of the PostgreSQL schema that owns the target table.
            Defaults to ``"public"``. Set this when writing to a non-default
            schema; the name is quoted identically to ``table_name``.
        max_batch_size: Maximum number of entries allowed to be committed within a
            single transaction.
        init_mode: "default": The default initialization mode;
            "create_if_not_exists": initializes the SQL writer by creating the necessary table
            if they do not already exist;
            "replace": Initializes the SQL writer by replacing any existing table.
        output_table_type: Defines how the output table manages its data. If set to ``"stream_of_changes"``
            (the default), the system outputs a stream of modifications to the target table.
            This stream includes two additional integer columns: ``time``, representing the computation
            minibatch, and ``diff``, indicating the type of change (``1`` for row addition and
            ``-1`` for row deletion). If set to ``"snapshot"``, the table maintains the current