ClickHouse/tests/queries/0_stateless/01051_system_stack_trace.sql
Azat Khuzhin 531e3b13ce Optimize accesses to system.stack_trace (filter by name before sending signal)
Because of failed rebase/push this part of the patch was lost, so
resending separatelly (sigh).

Follow-up for: #39177 (cc @yakov-olkhovskiy)
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
2022-07-14 11:49:34 +03:00

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SQL

-- Tags: race
-- { echo }
SELECT count() > 0 FROM system.stack_trace WHERE query_id != '';
-- opimization for not reading /proc/self/task/{}/comm and avoid sending signal
SELECT countIf(thread_id > 0) > 0 FROM system.stack_trace;
-- optimization for trace
SELECT length(trace) > 0 FROM system.stack_trace LIMIT 1;
-- optimization for query_id
SELECT length(query_id) > 0 FROM system.stack_trace WHERE query_id != '' LIMIT 1;
-- optimization for thread_name
SELECT length(thread_name) > 0 FROM system.stack_trace WHERE thread_name != '' LIMIT 1;
-- enough rows (optimizations works "correctly")
SELECT count() > 100 FROM system.stack_trace;