Module delta_io 

Delta Lake I/O integration module.

This module provides the actual I/O operations for Delta Lake tables via the deltalake crate. All functions are feature-gated behind delta-lake.

Architecture

The I/O module is separate from the business logic in delta.rs to allow:

• Testing business logic without the deltalake dependency
• Clean separation of concerns (buffering/epoch management vs. actual writes)
• Easy mocking for unit tests

Coordinated exactly-once publication uses runtime-owned, stable transaction namespaces. Ordinary direct writes do not emit writer-local transaction actions because a process-random identity cannot deduplicate recovery.

Structs

MergeResult

Result of a MERGE (upsert) operation.

ResolvedCatalogTable

A table location resolved through its catalog.

Enums

CatalogAccess

Whether a catalog-resolved table is opened for reading or for commits.

Functions

credentials_need_refresh

Whether credentials expiring at expire_at must be renewed before the next storage I/O.

credentials_refresh_at

When credentials expiring at expire_at are due for renewal.

get_coordinated_cursor

Read the atomic checkpoint/fencing cursor for one coordinated namespace.

get_latest_version

Returns the latest committed version via the log store.

get_partition_columns

Returns the table’s partition columns, or an empty list if the snapshot is unavailable. Best-effort: used for clustering diagnostics, never for correctness, so a missing snapshot is not an error.

get_table_schema

Extracts the Arrow schema from a Delta Lake table.

map_cdf_to_changelog

Maps Delta CDF rows to the canonical signed-weight changelog and drops CDF metadata columns (_change_type, _commit_version, _commit_timestamp).

open_or_create_partitioned_table

Opens an existing Delta table, or creates it with schema partitioned by partition_columns when it is absent and a schema is supplied. An existing table keeps its own partitioning; callers compare it with their configuration.

open_or_create_table

Opens an existing Delta Lake table or creates a new one.

open_table_metadata

Opens an existing table’s log metadata (version, metaData, protocol) without materializing its file list, which a reader that scans through the Delta kernel never needs.

resolve_catalog_options

Resolves catalog-aware table URI and merges catalog-specific storage options.