SQLQueryBackend¶

API reference for SQLQueryBackend --- read-only SQL query materializer that maps path keys to SQL queries and serializes results to Parquet, CSV, or Arrow IPC.

SQLQueryBackend ¶

SQLQueryBackend(
    url: str | None = None,
    *,
    engine: Engine | None = None,
    queries: dict[str, str] | None = None,
    strict: bool = True,
    serializer: ResultSerializer | None = None,
)

Read-only SQL query materializer implementing a subset of the Backend contract.

Maps path keys to SQL queries. On read(), executes the query and serializes the result set to the format implied by the key's file extension (Parquet, CSV, or Arrow IPC).

Capabilities: READ, LIST, METADATA, GLOB, SEEKABLE_READ.

resolve ¶

resolve(path: str) -> ResolutionPlan

Return a ResolutionPlan with SQL query details.

Parameters:

path (str) –

Backend-relative key.

Returns:

ResolutionPlan –

Plan with kind="sql-query" and details containing
ResolutionPlan –

source and format.

Serialization¶

ResultSerializer ¶

Converts SQL result rows to bytes in a specific format.

serialize ¶

serialize(
    rows: Sequence[Any], columns: Sequence[str], format: str
) -> bytes

Serialize rows with given column names to the specified format.

Parameters:

rows (Sequence[Any]) –

Sequence of row tuples from SQL execution.
columns (Sequence[str]) –

Column name list.
format (str) –

Target format ("parquet", "csv", "arrow").

Returns:

bytes –

Serialized bytes.

ArrowSerializer ¶

Serializes SQL result sets via PyArrow.

Converts rows + columns to a pyarrow.Table, then writes to the requested format. Imports pyarrow lazily so that SQLBlobBackend remains importable without it.

serialize ¶

serialize(
    rows: Sequence[Any], columns: Sequence[str], format: str
) -> bytes

Serialize rows to Parquet, CSV, or Arrow IPC.