agnes-the-ai-analyst/app/api/v2_schema.py
ZdenekSrotyr e5fb913cec perf: Tier 1 event-loop unblocking — async def → def on BQ-bound handlers
Five hottest BQ-touching endpoints were `async def` but invoked synchronous
DuckDB / BQ-extension calls inside the body. Under uvicorn's single event
loop that meant a single heavy `agnes query --remote` (waiting up to
~200 s for BQ's jobs.query) froze EVERY other request — /api/health,
dashboard, auth, even another query — for the full BQ wait. Operators
saw "VM idle, app frozen" during PR #188's testing.

Convert to plain `def` so FastAPI auto-offloads the body to the anyio
thread pool. Event loop stays free for non-BQ requests.

- app/api/query.py:execute_query
- app/api/v2_scan.py:scan_estimate_endpoint, scan_endpoint
- app/api/v2_sample.py:sample
- app/api/v2_schema.py:schema

Audit: 0 `await` statements in any converted handler (verified file-by-
file), so the rename is safe. Tests in tests/test_v2_*.py called the
handlers via `asyncio.run(...)` which now fails on a non-coroutine return;
swapped for direct calls (asyncio.run( -> ( ) — keeps paren balance).

Plus AGNES_THREADPOOL_SIZE env var (default 200, was anyio's stock 40)
in app/main.py:lifespan. Set via
anyio.to_thread.current_default_thread_limiter().total_tokens. 200 is
comfortable headroom for <50 concurrent analysts; bump for more.

480/480 impacted tests pass (the 2 remaining errors are a pre-existing
fixture setup issue in test_reader_smoke_matrix.py unrelated to this
change).
2026-05-05 17:44:08 +02:00

235 lines
9 KiB
Python

"""GET /api/v2/schema/{table_id} — table column metadata (spec §3.2)."""
from __future__ import annotations
import logging
from fastapi import APIRouter, Depends, HTTPException
import duckdb
from app.auth.dependencies import get_current_user, _get_db
from src.rbac import can_access_table
from src.repositories.table_registry import TableRegistryRepository
from app.api.v2_cache import TTLCache
from connectors.bigquery.access import BqAccess, BqAccessError, get_bq_access
logger = logging.getLogger(__name__)
router = APIRouter(prefix="/api/v2", tags=["v2"])
_schema_cache = TTLCache(maxsize=512, ttl_seconds=3600)
class NotFound(Exception):
pass
_BQ_DIALECT_HINTS = {
"date_literal": "DATE '2026-01-01'",
"timestamp_literal": "TIMESTAMP '2026-01-01 00:00:00 UTC'",
"interval_subtract": "DATE_SUB(CURRENT_DATE(), INTERVAL 30 DAY)",
"regex": "REGEXP_CONTAINS(field, r'pattern')",
"cast": "CAST(x AS INT64)",
}
def _fetch_bq_schema(bq, dataset: str, table: str) -> list[dict]:
"""Fetch column list via INFORMATION_SCHEMA.COLUMNS using DuckDB BQ extension.
`bq.duckdb_session()` provides a DuckDB conn with the bigquery extension
loaded + auth secret installed. SQL here is server-constructed (queries
INFORMATION_SCHEMA.COLUMNS with validated identifiers, no user-derived
fragments), so a BQ BadRequest means registry corruption, not user input
→ surfaces as `bq_upstream_error` (HTTP 502), same as `/sample`, opposite
of `/scan*`.
"""
from connectors.bigquery.access import translate_bq_error
from src.identifier_validation import validate_quoted_identifier
# Surface "BQ not configured" as the structured 500 BqAccessError(not_configured)
# with hint, not the misleading 400 unsafe_identifier the empty-string sentinel
# would otherwise trigger from validate_quoted_identifier below. Devin BUG_0002.
if not bq.projects.data:
bq.client() # raises BqAccessError(not_configured); endpoint catches it
# Defense in depth (cf. v2_sample) — registry already validates these,
# but the v2 endpoints are downstream of admin REST writes that could
# bypass that gate. A backtick in `dataset` would otherwise break out
# of `…` quoting and execute arbitrary BQ SQL.
if not (validate_quoted_identifier(bq.projects.data, "BQ project")
and validate_quoted_identifier(dataset, "BQ dataset")
and validate_quoted_identifier(table, "BQ source_table")):
raise ValueError("unsafe BQ identifier in registry — refusing to query")
bq_sql = (
f"SELECT column_name, data_type, is_nullable "
f"FROM `{bq.projects.data}.{dataset}.INFORMATION_SCHEMA.COLUMNS` "
f"WHERE table_name = ? ORDER BY ordinal_position"
)
with bq.duckdb_session() as conn:
try:
rows = conn.execute(
"SELECT * FROM bigquery_query(?, ?, ?)",
[bq.projects.billing, bq_sql, table],
).fetchall()
except Exception as e:
raise translate_bq_error(e, bq.projects, bad_request_status="upstream_error")
return [
{
"name": r[0],
"type": r[1],
"nullable": r[2] == "YES",
"description": "",
}
for r in rows
]
def _fetch_bq_table_options(bq, dataset: str, table: str) -> dict:
"""Best-effort fetch of partition/cluster info from INFORMATION_SCHEMA.COLUMNS.
BigQuery exposes partition + cluster metadata as per-column flags:
- `is_partitioning_column` ('YES' / 'NO') — at most one column per table
- `clustering_ordinal_position` (INT64, null for non-clustered columns;
otherwise 1, 2, ... in cluster-key order)
Returns `{}` on ANY failure (best-effort). The outer
`try/except Exception → return {}` is a load-bearing contract: the
/schema endpoint must keep returning 200 with empty partition info even
when this query fails (e.g. on permissioned tables, on cross-project
misconfigurations). DO NOT route this through `translate_bq_error` —
that would convert errors to BqAccessError which the endpoint would 502
on. See tests/test_v2_schema.py::test_schema_returns_200_with_empty_…
"""
from src.identifier_validation import validate_quoted_identifier
# Best-effort path: if BQ isn't configured (sentinel BqAccess), return
# empty partition info silently — operator gets schema (200) without
# failing on the missing config. The strict /schema path (_fetch_bq_schema)
# surfaces the not_configured error separately.
if not bq.projects.data:
return {}
if not (validate_quoted_identifier(bq.projects.data, "BQ project")
and validate_quoted_identifier(dataset, "BQ dataset")
and validate_quoted_identifier(table, "BQ source_table")):
return {} # Best-effort; refuse to query unsafe identifiers.
try:
with bq.duckdb_session() as conn:
bq_sql = (
f"SELECT column_name, is_partitioning_column, clustering_ordinal_position "
f"FROM `{bq.projects.data}.{dataset}.INFORMATION_SCHEMA.COLUMNS` "
f"WHERE table_name = ? "
f"ORDER BY clustering_ordinal_position NULLS LAST"
)
rows = conn.execute(
"SELECT * FROM bigquery_query(?, ?, ?)",
[bq.projects.billing, bq_sql, table],
).fetchall()
if not rows:
return {}
partition_by = next(
(r[0] for r in rows if (r[1] or "").upper() == "YES"),
None,
)
clustered_by = [r[0] for r in rows if r[2] is not None]
return {"partition_by": partition_by, "clustered_by": clustered_by}
except Exception as e:
logger.warning(
"BQ table options fetch failed for %s.%s.%s: %s",
bq.projects.data, dataset, table, e,
)
return {}
def build_schema(
conn: duckdb.DuckDBPyConnection,
user: dict,
table_id: str,
*,
bq: BqAccess,
) -> dict:
# RBAC + existence check MUST run before cache lookup — otherwise an
# unauthorized user can read cached schema fetched by an authorized one.
repo = TableRegistryRepository(conn)
row = repo.get(table_id)
if not row:
raise NotFound(table_id)
if not can_access_table(user, table_id, conn):
raise PermissionError(table_id)
cache_key = f"{table_id}"
cached = _schema_cache.get(cache_key)
if cached is not None:
return cached
source_type = row.get("source_type") or ""
if source_type == "bigquery":
dataset = row.get("bucket") or ""
source_table = row.get("source_table") or table_id
columns = _fetch_bq_schema(bq, dataset, source_table)
opts = _fetch_bq_table_options(bq, dataset, source_table)
payload = {
"table_id": table_id,
"source_type": source_type,
"sql_flavor": "bigquery",
"columns": columns,
"partition_by": opts.get("partition_by"),
"clustered_by": opts.get("clustered_by", []),
"where_dialect_hints": _BQ_DIALECT_HINTS,
}
else:
# Local source — read schema from the parquet via DuckDB
from pathlib import Path
from app.utils import get_data_dir
parquet = (
get_data_dir() / "extracts" / source_type / "data" / f"{table_id}.parquet"
)
local_conn = duckdb.connect(":memory:")
try:
cols = local_conn.execute(
"DESCRIBE SELECT * FROM read_parquet(?)", [str(parquet)]
).fetchall()
finally:
local_conn.close()
payload = {
"table_id": table_id,
"source_type": source_type,
"sql_flavor": "duckdb",
"columns": [
{"name": c[0], "type": c[1], "nullable": c[2] == "YES", "description": ""}
for c in cols
],
"partition_by": None,
"clustered_by": [],
"where_dialect_hints": {},
}
_schema_cache.set(cache_key, payload)
return payload
@router.get("/schema/{table_id}")
def schema(
table_id: str,
user: dict = Depends(get_current_user),
conn: duckdb.DuckDBPyConnection = Depends(_get_db),
bq: BqAccess = Depends(get_bq_access),
):
# Plain ``def`` — opens a `bq.duckdb_session()` and runs sync metadata
# queries through the BQ extension. See PR #188 Tier 1 entry.
try:
return build_schema(conn, user, table_id, bq=bq)
except NotFound:
raise HTTPException(status_code=404, detail=f"table {table_id!r} not found")
except PermissionError:
raise HTTPException(status_code=403, detail="not authorized for this table")
except ValueError as e:
raise HTTPException(
status_code=400,
detail={"error": "unsafe_identifier", "message": str(e), "details": {}},
)
except BqAccessError as e:
raise HTTPException(
status_code=BqAccessError.HTTP_STATUS.get(e.kind, 500),
detail={"error": e.kind, "message": e.message, "details": e.details},
)