Define Py PartitionedTableServiceBackend intf

py/server/deephaven/experimental/partitioned_table_service.py

@@ -0,0 +1,87 @@
+#
+# Copyright (c) 2016-2024 Deephaven Data Labs and Patent Pending
+#
+from abc import ABC, abstractmethod
+from typing import Tuple, Optional, Any, Callable, Iterable
+
+import pyarrow as pa
+
+class TableKey:
+    """A key that identifies a table. The key should be unique for each table. The key can be any Python object and
+    should include sufficient information to uniquely identify the table for the backend service."""
+
+    def __init__(self, key: Any):
+        self._key = key
+
+    @property
+    def key(self) -> Any:
+        return self._key
+
+
+class PartitionedTableLocationKey:
+    """A key that identifies a specific partition of a table. The key should be unique for each partition of the table.
+    The key can be any Python object and should include sufficient information to uniquely identify the partition for
+    the backend service to fetch the partition data.
+    """
+    def __init__(self, pt_location_key: Any):
+        self._pt_location_key = pt_location_key
+
+    @property
+    def pt_location_key(self) -> Any:
+        return self._pt_location_key
+
+
+class PartitionedTableServiceBackend(ABC):
+    """An interface for a backend service that provides access to partitioned data."""
+
+    @abstractmethod
+    def table_schema(self, table_key: Any) -> Tuple[pa.Schema, Optional[pa.Schema]]:
+        """ Returns the table schema and optionally the schema for the partition columns for the table with the given table key.
+        The table schema is not required to include the partition columns defined in the partition schema. THe partition columns
+        are limited to primitive types and strings.
+        """
+        pass
+
+    @abstractmethod
+    def existing_partitions(self, table_key: TableKey, callback: Callable[[PartitionedTableLocationKey, Optional[pa.Table]], None]) -> None:
+        """ Provides a callback for the backend service to pass the existing partitions for the table with the given table key.
+        The 2nd argument of the callback is an optional pa.Table that contains the values for the partitions. The schema of the table
+        should match the optional partition schema returned by table_schema() for the table_key. The table should have a single row
+        for the particular partition location key provided in the 1st argument, with the values for the partition columns in the row.
+        """
+        pass
+
+    @abstractmethod
+    def subscribe_to_new_partitions(self, table_key: TableKey, callback: Callable[[PartitionedTableLocationKey, Optional[pa.Table]], None]) -> Callable[[], None]:
+        """ Provides a callback for the backend service to pass new partitions for the table with the given table key.
+        The 2nd argument of the callback is a pa.Table that contains the values for the partitions. The schema of the table
+        should match the optional partition schema returned by table_schema() for the table_key. The table should have a single row
+        for the particular partition location key provided in the 1st argument, with the values for the partition columns in the row.
+
+        The return value is a function that can be called to unsubscribe from the new partitions.
+        """
+        pass
+
+    @abstractmethod
+    def partition_size(self, table_key: TableKey, table_location_key: PartitionedTableLocationKey, callback: Callable[[int], None]) -> None:
+        """ Provides a callback for the backend service to pass the size of the partition with the given table key and partition location key.
+        The callback should be called with the size of the partition in number of rows.
+        """
+        pass
+
+    @abstractmethod
+    def subscribe_to_partition_size_changes(self, table_key: TableKey, table_location_key: PartitionedTableLocationKey, callback: Callable[[int], None]) -> Callable[[], None]:
+        """ Provides a callback for the backend service to pass the changed size of the partition with the given table key and partition location key.
+        The callback should be called with the size of the partition in number of rows.
+
+        The return value is a function that can be called to unsubscribe from the partition size changes.
+        """
+        pass
+
+    @abstractmethod
+    def column_values(self, table_key: TableKey, table_location_key: PartitionedTableLocationKey, col: str) -> pa.Table:
+        """ Returns the values for the column with the given name for the partition with the given table key and partition location key.
+        The returned pa.Table should have a single column with the values for the given column.
+
+        """
+        pass