aminghadersohi commented on code in PR #45859:
URL: https://github.com/apache/superset/pull/45859#discussion_r4428425050
##########
superset/sql/execution/celery_task.py:
##########
@@ -661,6 +661,14 @@ def _execute_sql_statements(
level=ErrorLevel.ERROR,
)
) from ex
+ except Exception:
Review Comment:
If Stop races a real fetch or result-conversion failure (e.g.
`MemoryError`), this handler drops its traceback and `error_sqllab_unhandled`
metric for every engine. Preserve diagnostics for errors unrelated to
cancellation.
##########
docs/admin_docs/configuration/configuring-superset.mdx:
##########
@@ -835,6 +835,16 @@ pending when result fetching begins, the additional
polling wait is bounded by
a timeout. Configure the driver's network timeout separately to bound
individual
RPC calls.
+Impala reports a streaming `SELECT` as finished as soon as its rows can be
fetched,
+so most of such a query runs while SQL Lab reads its results. While it
fetches, the
+worker checks for a stop between result RPCs, at most once per
+`DB_POLL_INTERVAL_SECONDS`, and cancels the query on its own connection. Each
result
+RPC returns within Impala's `FETCH_ROWS_TIMEOUT_MS` query option (10 seconds by
+default, available from Impala 3.4) even when no rows are ready, so a stop
takes
+effect within about `FETCH_ROWS_TIMEOUT_MS` plus `DB_POLL_INTERVAL_SECONDS`;
+lowering either makes stops take effect sooner. Impala checks for cancellation
between row batches, so a batch whose
Review Comment:
`FETCH_ROWS_TIMEOUT_MS=0` makes fetch requests wait indefinitely, so
lowering it to zero can prevent Stop from being observed until the fetch
returns. The tuning guidance needs to require a positive value.
```suggestion
RPC returns within Impala's `FETCH_ROWS_TIMEOUT_MS` query option (10 seconds
by
default, available from Impala 3.4) when it is positive, even when no rows
are ready,
so a stop takes effect within about that timeout plus
`DB_POLL_INTERVAL_SECONDS`.
Lowering a positive timeout or the poll interval makes stops take effect
sooner.
Setting `FETCH_ROWS_TIMEOUT_MS=0` disables the timeout and can delay Stop
until the
fetch returns. Impala checks for cancellation between row batches, so a
batch whose
```
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