* Maintain per-thread timer_id rather than create/delete frequently
The QueryProfiler will frequently create/delete timer_id globally, which
will result in heavy kernel lock contention.
The idea is to maintain thread-local timer_id. Before create the
timer_id, it should check whether there is a timer_id already. And we
could stop the timer by timer_settime() rather than delete the timer_id
with timer_delete().
Apply the patch and run clickbench on latest 65d671b7c7 ClickHouse with
SPR 112 x 2 vCPUs. Query 4, 0, 5, 3, 15, 32 have 17.5%, 14.4%, 8.3%, 7.9%,
7.1%, 5.8% performance gain. The overall geomean has got 2.5%
performance gain.
Signed-off-by: Jiebin Sun <jiebin.sun@intel.com>
* Pack the timer and delete the timer_id when thread terminates
Pack the timer and related methods into the class. Delete the timer_id
when the thread terminates.
According to the issue (ClickHouse#49965),
all of the SSB queries benefit from this optimization, some have even got
improved by ~30% and the overall QPS could be significantly improved by ~18%.
Signed-off-by: Jiebin Sun <jiebin.sun@intel.com>
* Update src/Common/QueryProfiler.cpp
Co-authored-by: Azat Khuzhin <a3at.mail@gmail.com>
* Update src/Common/QueryProfiler.cpp
Co-authored-by: Azat Khuzhin <a3at.mail@gmail.com>
* Fix the review issue of QueryProfiler Timer from PR
https://github.com/ClickHouse/ClickHouse/pull/48778.
Signed-off-by: Jiebin Sun <jiebin.sun@intel.com>
* Update src/Common/QueryProfiler.cpp
Co-authored-by: Azat Khuzhin <a3at.mail@gmail.com>
* Add two separate CurrentMetrics for created and active timers
in QueryProfiler.
Signed-off-by: Jiebin Sun <jiebin.sun@intel.com>
---------
Signed-off-by: Jiebin Sun <jiebin.sun@intel.com>
Co-authored-by: Azat Khuzhin <a3at.mail@gmail.com>
Co-authored-by: Nikita Taranov <nikita.taranov@clickhouse.com>
$ clickhouse-benchmark -i 10000 -d 0 --parallelize_output_from_storages=0 -q "select * from values('foo')"
Loaded 1 queries.
Queries executed: 10000.
localhost:9000, queries 10000, QPS: 2800.490, RPS: 2800.490, MiB/s: 0.032, result RPS: 2800.490, result MiB/s: 0.032.
0.000% 0.000 sec.
10.000% 0.000 sec.
20.000% 0.000 sec.
30.000% 0.000 sec.
40.000% 0.000 sec.
50.000% 0.000 sec.
60.000% 0.000 sec.
70.000% 0.000 sec.
80.000% 0.000 sec.
90.000% 0.000 sec.
95.000% 0.000 sec.
99.000% 0.001 sec.
99.900% 0.001 sec.
99.990% 0.001 sec.
$ clickhouse-benchmark -i 10000 -d 0 --parallelize_output_from_storages=1 -q "select * from values('foo')"
Loaded 1 queries.
Queries executed: 10000.
localhost:9000, queries 10000, QPS: 1259.805, RPS: 1259.805, MiB/s: 0.014, result RPS: 1259.805, result MiB/s: 0.014.
0.000% 0.001 sec.
10.000% 0.001 sec.
20.000% 0.001 sec.
30.000% 0.001 sec.
40.000% 0.001 sec.
50.000% 0.001 sec.
60.000% 0.001 sec.
70.000% 0.001 sec.
80.000% 0.001 sec.
90.000% 0.001 sec.
95.000% 0.001 sec.
99.000% 0.001 sec.
99.900% 0.001 sec.
99.990% 0.003 sec.
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
Adding more processors for parallelize_output_from_storages is not a
costless operation (I've experienced some issues in production because
of this), and it is not easy to fix in a normal way, so let's disable it
for now.
Before this patch:
- INSERT INTO input SELECT * FROM numbers(10e6) SETTINGS parallelize_output_from_storages=1, min_insert_block_size_rows=1000
0 rows in set. Elapsed: 3.648 sec. Processed 20.00 million rows, 120.00 MB (5.48 million rows/s., 32.90 MB/s.)
- INSERT INTO input SELECT * FROM numbers(10e6) SETTINGS parallelize_output_from_storages=0, min_insert_block_size_rows=1000
0 rows in set. Elapsed: 1.851 sec. Processed 20.00 million rows, 120.00 MB (10.80 million rows/s., 64.82 MB/s.)
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
Updated PostgreSQL documentation to better show example of using PostgreSQL() table engine for SELECT and INSERT, vs. copying data via postgresql() table function for copying data into ClickHouse
Empty table overrides are formatted without any parenthesises,
but they are required by a parser,
and it is not possible to parse empty table overrides without it.
:) CREATE DATABASE db ... TABLE OVERRIDE t1()
CREATE DATABASE db
...
TABLE OVERRIDE `t1`
This query will be saved to metadata and ClickHouse will not be able to start up, since
table overrides require ().
