Function explain

misc/python/materialize/mzexplore/extract.py:453–482

(
    db: sql.Database,
    explain_stage: ExplainStage,
    explainee: str,
    explain_options: list[ExplainOption],
    explain_format: ExplainFormat,
)

def explain(
    db: sql.Database,
    explain_stage: ExplainStage,
    explainee: str,
    explain_options: list[ExplainOption],
    explain_format: ExplainFormat,
) -> str:
    explain_query = "\n".join(
        line
        for line in [
            f"EXPLAIN {explain_stage}",
            f"WITH({', '.join(map(str, explain_options))})" if explain_options else "",
            f"AS {explain_format} FOR",
            explainee,
        ]
        if line != ""
    )
    if explain_stage == ExplainStage.OPTIMIZER_TRACE:
        return json.dumps(
            {
                "explainee": {"query": explainee},
                "list": [
                    {"id": id, **entry}
                    for (id, entry) in enumerate(db.query_all(explain_query))
                ],
            },
            indent=4,
        )
    else:
        return next(iter(db.query_one(explain_query).values()))


def explain_item(item_type: ItemType, fqname: str, replan: bool) -> str | None: