tlc.core.objects.tables.from_url.table_from_row_cache

A table representing another, potentially unregistered, Table type from a URL

Module Contents

Classes

Class

Description

TableFromRowCache

A table that wraps another table based on its row cache.

API

class TableFromRowCache(
init_parameters: Any,
url: Url | None = None,
)

Bases: tlc.core.objects.tables.from_url.table_from_parquet.TableFromParquet

A table that wraps another table based on its row cache.

A TableFromRowCache enables a limited representation of unknown Table types that are not registered in the system. Note that the UnknownTable’s derived properties are not initialized and are only present as plain objects.

The TableFromRowCache is not intended for direct instantiation, use the TableFromParquet whenever explicit loading of tables from parquet files is desired. Instead, the TableFromRowCache should be used as a utility for loading and representing tables that are not registered in the system. It offers an abstracted interface to work with these unknown table types while maintaining system integrity.

The implementation is a minimal wrapper around TableFromParquet.

This TableFromRowCache can be used to represent other Table types as long as the following requirements are met:

  • The object must have a row_cache_url set

  • The object must have row_cache_populated set

  • The object must have a schema set

Limitations:

  • Initialization: TableFromRowCache can only be initialized using the init_params as is done when calling Table.from_url or ObjectRegistry.get_or_create_object_from_url. Direct initialization is not supported. Use TableFromParquet instead.

  • Write Restriction: The table cannot be written to a URL since it would mean overwriting the original table and losing information therein. Again, use TableFromParquet if a persistent table is desired.

  • Plain attributes: Derived attributes are not initialized and are plain objects, for example: input_urls are strings and not Url objects.

Parameters:

init_parameters – The parameters to initialize the object with.

Parameters:

  • url – The URL of the table.

  • created – The creation time of the table.

  • description – The description of the table.

  • row_cache_url – The URL of the row cache.

  • row_cache_populated – Whether the row cache is populated.

  • override_table_rows_schema – The schema to override the table rows schema.

  • init_parameters – The initial parameters of the table.

  • input_tables – A list of Table URLs that are considered direct predecessors in this table’s lineage. This parameter serves as an explicit mechanism for tracking table relationships beyond the automatic lineage tracing typically managed by subclasses.

static can_create_from_content(
parameters: Any,
) → type[Object] | None

Determines whether a TableFromRowCache can be created from the given parameters.

This can be used to determine whether a serialized Table of another type can be represented as a TableFromRowCache. The following is required:

  • The table must have a row_cache_url set

  • The table must have a row_cache_populated set

  • The table must have a schema set

Parameters:

parameters – The parameters to check.

Returns:

The type of the object that can be created from the given parameters, or None if no object can be created.

write_to_url(
force: bool = False,
) → Url