vgi.exceptions

Module overview

Exception classes for VGI.

This module defines custom exceptions used throughout the VGI framework.

class BindStateNotFoundError

source

Bases: Exception

Description

Raised when init is called with invalid or missing bind_data.

This exception is raised when:

• INIT invocation is missing bind_data field
• The bind_data is corrupted or cannot be deserialized
• The function_name in bind state doesn’t match the invocation

The client should catch this and provide a clear error message indicating that a BIND call must be made before INIT.

class CatalogReadOnlyError

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Bases: Exception

Description

Raised when a DDL operation is attempted on a read-only catalog.

This exception is raised by ReadOnlyCatalogInterface when any create, drop, rename, or modify operation is attempted.

Read-only catalogs only support:

• catalogs() - list catalogs
• catalog_attach/detach - attach to/detach from catalogs
• schemas() - list schemas
• schema_get() - get schema info
• schema_contents() - list schema contents
• table_get(), view_get() - get table/view info
• table_scan_function_get() - get scan function for tables

class ExecutionIdentifierError

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Bases: ValueError

Description

Raised when an operation requires an execution_identifier that hasn’t been set.

This typically occurs when:

• store_state() is called before initialize_global_state() or load_global_state()
• collect_states() is called before initialize_global_state() or load_global_state()
• Work queue operations are attempted before initialization

The execution_identifier is automatically set during:

• initialize_global_state() for the primary worker
• load_global_state() for secondary workers

Resolution:

• Ensure your function calls super().initialize_global_state()
• Ensure the worker correctly calls load_global_state() for secondary workers

class SchemaValidationError

source

Bases: Exception

Description

Raised when a batch schema doesn’t match the expected schema.

This error is raised by the framework during input/output validation. It indicates a programming error where a batch doesn’t conform to the declared schema.

The error message includes detailed information about what differs:

• Missing fields (in expected but not in actual)
• Extra fields (in actual but not in expected)
• Type mismatches (same field name, different types)
• Field order differences

Attributes

attribute expected

pa.Schema | None

The expected Arrow schema.

attribute actual

pa.Schema | None

The actual Arrow schema that was received.

attribute context

str

Description of where the validation occurred.