Re: Pg10 : Client Configuration for Parallelism ?
Thomas Kellerer writes: > laurent.decha...@orange.com schrieb am 17.04.2019 um 16:33: >> On jdbc it seems this is equivalent to write : >> statement. setMaxRows(0); // parallelism authorized, which is the default. >> >> Thus on my jdbc basic program if I add : >> statement. setMaxRows(100); // No parallelism allowed (at least in Pg10) > This isn't limited to Statement.setMaxRows() > If you use "LIMIT x" in your SQL query, the same thing happens. No, not true: queries with LIMIT x are perfectly parallelizable. The trouble with the protocol-level limit (setMaxRows) is that it requires being able to suspend the query and resume fetching rows later. We don't allow that for parallel query because it would involve tying up vastly more resources, ie a bunch of worker processes, not just some extra memory in the client's own backend. regards, tom lane
Re: Pg10 : Client Configuration for Parallelism ?
laurent.decha...@orange.com schrieb am 17.04.2019 um 16:33: Hello Justin and thank you for your clues. Finally I found that putting blank to the option that limits the number of rows to retrieve (which is normal for this kind of tool) allows PostgreSQL to parallelize the query. On jdbc it seems this is equivalent to write : statement. setMaxRows(0); // parallelism authorized, which is the default. Thus on my jdbc basic program if I add : statement. setMaxRows(100); // No parallelism allowed (at least in Pg10) Thanks to all who were kind enough to help. This isn't limited to Statement.setMaxRows() If you use "LIMIT x" in your SQL query, the same thing happens. Thomas
Re: Pg10 : Client Configuration for Parallelism ?
laurent.decha...@orange.com wrote:
> There is something in documentation that says that there won't be parallelism
> if " The client sends an Execute message with a non-zero fetch count."
> I am not sure what this sentence means.
The JDBC driver sends an "Execute" message to the server.
https://www.postgresql.org/docs/current/protocol-message-formats.html says:
Execute (F)
Byte1('E')
Identifies the message as an Execute command.
Int32
Length of message contents in bytes, including self.
String
The name of the portal to execute (an empty string selects the unnamed
portal).
Int32
Maximum number of rows to return, if portal contains a query that
returns rows
(ignored otherwise). Zero denotes “no limit”.
If you use setMaxRows non-zero, that number is sent as the "maximum number of
rows".
Parallelism currently cannot be used if there is a limit on the row count.
Imagine you want ten rows and already have nine, now if two workers are busy
calculating the next row, there is no good way to stop one of them when the
other
returns a row.
Yours,
Laurenz Albe
--
Cybertec | https://www.cybertec-postgresql.com
RE: Pg10 : Client Configuration for Parallelism ?
Hello Justin and thank you for your clues. Finally I found that putting blank to the option that limits the number of rows to retrieve (which is normal for this kind of tool) allows PostgreSQL to parallelize the query. On jdbc it seems this is equivalent to write : statement. setMaxRows(0); // parallelism authorized, which is the default. Thus on my jdbc basic program if I add : statement. setMaxRows(100); // No parallelism allowed (at least in Pg10) Thanks to all who were kind enough to help. Laurent -Message d'origine- De : Justin Pryzby [mailto:pry...@telsasoft.com] Envoyé : mercredi 17 avril 2019 15:57 À : DECHAMBE Laurent DTSI/DSI Cc : Andreas Joseph Krogh; pgsql-performance@lists.postgresql.org Objet : Re: Pg10 : Client Configuration for Parallelism ? On Wed, Apr 17, 2019 at 09:51:02AM +, laurent.decha...@orange.com wrote: > > 2019-04-17 11:30:42 CEST;35895;thedbuser;thedb;0;LOG: 0: execute > : SELECT COUNT(1) FROM big_table > 2019-04-17 11:30:42 CEST;35895;thedbuser;thedb;0;LOCATION: > exec_execute_message, postgres.c:1959 "execute" means it's using the extended protocol. https://www.postgresql.org/docs/11/protocol-flow.html#PROTOCOL-FLOW-EXT-QUERY > > 2019-04-17 11:31:20 CEST;37257;thedbuser;thedb;0;LOG: 0: execute > : SELECT COUNT(1) FROM big_table > 2019-04-17 11:31:20 CEST;37257;thedbuser;thedb;0;LOCATION: > exec_execute_message, postgres.c:1959 Same. > > 2019-04-17 11:32:56 CEST;37324;thedbuser;thedb;0;LOG: 0: statement: > SELECT COUNT(1) FROM big_table; > 2019-04-17 11:32:56 CEST;37324;thedbuser;thedb;0;LOCATION: > exec_simple_query, postgres.c:940 This is a "simple query", not using the "extended protocol". On Wed, Apr 17, 2019 at 11:26:07AM +, laurent.decha...@orange.com wrote: > There is something in documentation that says that there won't be parallelism > if " The client sends an Execute message with a non-zero fetch count." > I am not sure what this sentence means. This is likely the cause of the difference. Could you run wireshark to watch the protocol traffic ? I think it'll show that dbeaver is retrieving a portion of the result set. Justin _ Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration, Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci. This message and its attachments may contain confidential or privileged information that may be protected by law; they should not be distributed, used or copied without authorisation. If you have received this email in error, please notify the sender and delete this message and its attachments. As emails may be altered, Orange is not liable for messages that have been modified, changed or falsified. Thank you.
Re: Pg10 : Client Configuration for Parallelism ?
On Wed, Apr 17, 2019 at 09:51:02AM +, laurent.decha...@orange.com wrote: > > 2019-04-17 11:30:42 CEST;35895;thedbuser;thedb;0;LOG: 0: execute > : SELECT COUNT(1) FROM big_table > 2019-04-17 11:30:42 CEST;35895;thedbuser;thedb;0;LOCATION: > exec_execute_message, postgres.c:1959 "execute" means it's using the extended protocol. https://www.postgresql.org/docs/11/protocol-flow.html#PROTOCOL-FLOW-EXT-QUERY > > 2019-04-17 11:31:20 CEST;37257;thedbuser;thedb;0;LOG: 0: execute > : SELECT COUNT(1) FROM big_table > 2019-04-17 11:31:20 CEST;37257;thedbuser;thedb;0;LOCATION: > exec_execute_message, postgres.c:1959 Same. > > 2019-04-17 11:32:56 CEST;37324;thedbuser;thedb;0;LOG: 0: statement: > SELECT COUNT(1) FROM big_table; > 2019-04-17 11:32:56 CEST;37324;thedbuser;thedb;0;LOCATION: > exec_simple_query, postgres.c:940 This is a "simple query", not using the "extended protocol". On Wed, Apr 17, 2019 at 11:26:07AM +, laurent.decha...@orange.com wrote: > There is something in documentation that says that there won't be parallelism > if " The client sends an Execute message with a non-zero fetch count." > I am not sure what this sentence means. This is likely the cause of the difference. Could you run wireshark to watch the protocol traffic ? I think it'll show that dbeaver is retrieving a portion of the result set. Justin
Re: Pg10 : Client Configuration for Parallelism ?
On 4/17/2019 4:33, Thomas Kellerer wrote: A CTE would prevent parallelism. You mean like always? His SELECT count(1) FROM BigTable would be parallel if run alone but as WITH Data AS (SELECT count(1) FROM BigTable) SELECT * FROM Data nothing would be parallel any more? How about: SELECT * FROM (SELECT count(1) FROM BigTable) x Parallel or not? -Gunther
Re: Pg10 : Client Configuration for Parallelism ?
By the way On 4/17/2019 7:26, laurent.decha...@orange.com wrote: I can see whether there is parallelism with pg_top or barely top on the server. PID USER PR NIVIRTRESSHR S %CPU %MEM TIME+ COMMAND 38584 postgres 20 0 8863828 8.153g 8.151g R 100.0 3.2 1:23.01 postgres 10 root 20 0 0 0 0 S 0.3 0.0 88:07.26 rcu_sched PID USER PR NIVIRTRESSHR S %CPU %MEM TIME+ COMMAND 46687 postgres 20 0 8864620 0.978g 0.977g S 38.5 0.4 0:01.16 postgres 46689 postgres 20 0 8864348 996.4m 995.1m R 38.5 0.4 0:01.16 postgres 46690 postgres 20 0 8864348 987.2m 985.8m S 38.5 0.4 0:01.16 postgres 46691 postgres 20 0 8864348 998436 997084 R 38.5 0.4 0:01.16 postgres ... 46682 postgres 20 0 157996 2596 1548 R 0.7 0.0 0:00.05 top If you just use top with the -c option, you will see each postgres process identify itself as to its role, e.g. postgres: parallel worker for PID 46687 or postgres: SELECT ... or postgres: wal writer extremely useful this. -Gunther
RE: Pg10 : Client Configuration for Parallelism ?
loops=1 Worker 2: actual time=0.171..1.782 rows=18377525 loops=1 Worker 3: actual time=0.135..10036.104 rows=18161056 loops=1 Worker 4: actual time=0.116..10027.937 rows=18517339 loops=1 Worker 5: actual time=0.113..10036.766 rows=18198240 loops=1 Worker 6: actual time=0.115..10047.908 rows=18732838 loops=1 Worker 7: actual time=0.157..10035.136 rows=18189018 loops=1 Worker 8: actual time=0.132..10040.186 rows=18164384 loops=1 2019-04-17 14:47:51 CEST;55222;thedbuser;thedb;0;LOCATION: explain_ExecutorEnd, auto_explain.c:359 -Message d'origine- De : DECHAMBE Laurent DTSI/DSI Envoyé : mercredi 17 avril 2019 13:26 À : 'Andreas Kretschmer'; pgsql-performance@lists.postgresql.org Objet : RE: Pg10 : Client Configuration for Parallelism ? I can see whether there is parallelism with pg_top or barely top on the server. PID USER PR NIVIRTRESSHR S %CPU %MEM TIME+ COMMAND 38584 postgres 20 0 8863828 8.153g 8.151g R 100.0 3.2 1:23.01 postgres 10 root 20 0 0 0 0 S 0.3 0.0 88:07.26 rcu_sched PID USER PR NIVIRTRESSHR S %CPU %MEM TIME+ COMMAND 46687 postgres 20 0 8864620 0.978g 0.977g S 38.5 0.4 0:01.16 postgres 46689 postgres 20 0 8864348 996.4m 995.1m R 38.5 0.4 0:01.16 postgres 46690 postgres 20 0 8864348 987.2m 985.8m S 38.5 0.4 0:01.16 postgres 46691 postgres 20 0 8864348 998436 997084 R 38.5 0.4 0:01.16 postgres 46692 postgres 20 0 8864348 982612 981260 S 38.5 0.4 0:01.16 postgres 46693 postgres 20 0 8864348 979.9m 978.6m R 38.5 0.4 0:01.16 postgres 46694 postgres 20 0 8864348 987.9m 986.6m S 38.5 0.4 0:01.16 postgres 46696 postgres 20 0 8864348 996864 995512 S 38.5 0.4 0:01.16 postgres 46688 postgres 20 0 8864348 982.3m 981.0m R 38.2 0.4 0:01.15 postgres 46695 postgres 20 0 8864348 986.9m 985.6m S 38.2 0.4 0:01.15 postgres 21323 postgres 20 0 8862788 8.096g 8.095g S 0.7 3.2 2:24.75 postgres 46682 postgres 20 0 157996 2596 1548 R 0.7 0.0 0:00.05 top This is not a matter of cache. If I execute the queries in a different order the result will be the same : DBeaver query is longer. There is something in documentation that says that there won't be parallelism if " The client sends an Execute message with a non-zero fetch count." I am not sure what this sentence means. -Message d'origine- De : Andreas Kretschmer [mailto:andr...@a-kretschmer.de] Envoyé : mercredi 17 avril 2019 12:39 À : pgsql-performance@lists.postgresql.org Objet : Re: Pg10 : Client Configuration for Parallelism ? Am 17.04.19 um 11:51 schrieb laurent.decha...@orange.com: > > Here are the logs (with log_error_verbosity = verbose) : > > > > 2019-04-17 11:30:42 CEST;35895;thedbuser;thedb;0;LOG: 0: > execute : SELECT COUNT(1) FROM big_table > > 2019-04-17 11:30:42 CEST;35895;thedbuser;thedb;0;LOCATION: > exec_execute_message, postgres.c:1959 > > 2019-04-17 11:31:08 CEST;35895;thedbuser;thedb;0;LOG: 0: > duration: 25950.908 ms > > > > 2019-04-17 11:31:20 CEST;37257;thedbuser;thedb;0;LOG: 0: > execute : SELECT COUNT(1) FROM big_table > > 2019-04-17 11:31:20 CEST;37257;thedbuser;thedb;0;LOCATION: > exec_execute_message, postgres.c:1959 > > 2019-04-17 11:31:32 CEST;37257;thedbuser;thedb;0;LOG: 0: > duration: 11459.943 ms > > > > > 2019-04-17 11:32:56 CEST;37324;thedbuser;thedb;0;LOG: 0: > statement: SELECT COUNT(1) FROM big_table; > > 2019-04-17 11:32:56 CEST;37324;thedbuser;thedb;0;LOCATION: > exec_simple_query, postgres.c:940 > > 2019-04-17 11:33:08 CEST;37324;thedbuser;thedb;0;LOG: 0: > duration: 11334.677 ms > > That's compareable. The first one took more time, cold cache. The 2nd and 3rd are faster, warm cache. But: we can't see if the execution is paralell or not. If you want to know that, install and use auto_explain. Regards, Andreas -- 2ndQuadrant - The PostgreSQL Support Company. www.2ndQuadrant.com _ Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration, Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci. This message and its attachments may
RE: Pg10 : Client Configuration for Parallelism ?
I can see whether there is parallelism with pg_top or barely top on the server. PID USER PR NIVIRTRESSHR S %CPU %MEM TIME+ COMMAND 38584 postgres 20 0 8863828 8.153g 8.151g R 100.0 3.2 1:23.01 postgres 10 root 20 0 0 0 0 S 0.3 0.0 88:07.26 rcu_sched PID USER PR NIVIRTRESSHR S %CPU %MEM TIME+ COMMAND 46687 postgres 20 0 8864620 0.978g 0.977g S 38.5 0.4 0:01.16 postgres 46689 postgres 20 0 8864348 996.4m 995.1m R 38.5 0.4 0:01.16 postgres 46690 postgres 20 0 8864348 987.2m 985.8m S 38.5 0.4 0:01.16 postgres 46691 postgres 20 0 8864348 998436 997084 R 38.5 0.4 0:01.16 postgres 46692 postgres 20 0 8864348 982612 981260 S 38.5 0.4 0:01.16 postgres 46693 postgres 20 0 8864348 979.9m 978.6m R 38.5 0.4 0:01.16 postgres 46694 postgres 20 0 8864348 987.9m 986.6m S 38.5 0.4 0:01.16 postgres 46696 postgres 20 0 8864348 996864 995512 S 38.5 0.4 0:01.16 postgres 46688 postgres 20 0 8864348 982.3m 981.0m R 38.2 0.4 0:01.15 postgres 46695 postgres 20 0 8864348 986.9m 985.6m S 38.2 0.4 0:01.15 postgres 21323 postgres 20 0 8862788 8.096g 8.095g S 0.7 3.2 2:24.75 postgres 46682 postgres 20 0 157996 2596 1548 R 0.7 0.0 0:00.05 top This is not a matter of cache. If I execute the queries in a different order the result will be the same : DBeaver query is longer. There is something in documentation that says that there won't be parallelism if " The client sends an Execute message with a non-zero fetch count." I am not sure what this sentence means. -Message d'origine- De : Andreas Kretschmer [mailto:andr...@a-kretschmer.de] Envoyé : mercredi 17 avril 2019 12:39 À : pgsql-performance@lists.postgresql.org Objet : Re: Pg10 : Client Configuration for Parallelism ? Am 17.04.19 um 11:51 schrieb laurent.decha...@orange.com: > > Here are the logs (with log_error_verbosity = verbose) : > > > > 2019-04-17 11:30:42 CEST;35895;thedbuser;thedb;0;LOG: 0: > execute : SELECT COUNT(1) FROM big_table > > 2019-04-17 11:30:42 CEST;35895;thedbuser;thedb;0;LOCATION: > exec_execute_message, postgres.c:1959 > > 2019-04-17 11:31:08 CEST;35895;thedbuser;thedb;0;LOG: 0: > duration: 25950.908 ms > > > > 2019-04-17 11:31:20 CEST;37257;thedbuser;thedb;0;LOG: 0: > execute : SELECT COUNT(1) FROM big_table > > 2019-04-17 11:31:20 CEST;37257;thedbuser;thedb;0;LOCATION: > exec_execute_message, postgres.c:1959 > > 2019-04-17 11:31:32 CEST;37257;thedbuser;thedb;0;LOG: 0: > duration: 11459.943 ms > > > > > 2019-04-17 11:32:56 CEST;37324;thedbuser;thedb;0;LOG: 0: > statement: SELECT COUNT(1) FROM big_table; > > 2019-04-17 11:32:56 CEST;37324;thedbuser;thedb;0;LOCATION: > exec_simple_query, postgres.c:940 > > 2019-04-17 11:33:08 CEST;37324;thedbuser;thedb;0;LOG: 0: > duration: 11334.677 ms > > That's compareable. The first one took more time, cold cache. The 2nd and 3rd are faster, warm cache. But: we can't see if the execution is paralell or not. If you want to know that, install and use auto_explain. Regards, Andreas -- 2ndQuadrant - The PostgreSQL Support Company. www.2ndQuadrant.com _ Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration, Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci. This message and its attachments may contain confidential or privileged information that may be protected by law; they should not be distributed, used or copied without authorisation. If you have received this email in error, please notify the sender and delete this message and its attachments. As emails may be altered, Orange is not liable for messages that have been modified, changed or falsified. Thank you.
Re: Pg10 : Client Configuration for Parallelism ?
Am 17.04.19 um 11:51 schrieb laurent.decha...@orange.com: Here are the logs (with log_error_verbosity = verbose) : 2019-04-17 11:30:42 CEST;35895;thedbuser;thedb;0;LOG: 0: execute : SELECT COUNT(1) FROM big_table 2019-04-17 11:30:42 CEST;35895;thedbuser;thedb;0;LOCATION: exec_execute_message, postgres.c:1959 2019-04-17 11:31:08 CEST;35895;thedbuser;thedb;0;LOG: 0: duration: 25950.908 ms 2019-04-17 11:31:20 CEST;37257;thedbuser;thedb;0;LOG: 0: execute : SELECT COUNT(1) FROM big_table 2019-04-17 11:31:20 CEST;37257;thedbuser;thedb;0;LOCATION: exec_execute_message, postgres.c:1959 2019-04-17 11:31:32 CEST;37257;thedbuser;thedb;0;LOG: 0: duration: 11459.943 ms 2019-04-17 11:32:56 CEST;37324;thedbuser;thedb;0;LOG: 0: statement: SELECT COUNT(1) FROM big_table; 2019-04-17 11:32:56 CEST;37324;thedbuser;thedb;0;LOCATION: exec_simple_query, postgres.c:940 2019-04-17 11:33:08 CEST;37324;thedbuser;thedb;0;LOG: 0: duration: 11334.677 ms That's compareable. The first one took more time, cold cache. The 2nd and 3rd are faster, warm cache. But: we can't see if the execution is paralell or not. If you want to know that, install and use auto_explain. Regards, Andreas -- 2ndQuadrant - The PostgreSQL Support Company. www.2ndQuadrant.com
RE: Pg10 : Client Configuration for Parallelism ?
As answered to Andreas Kretschmer all settings are identical.
I have made some other tests, even testing a basic jdbc program (open
connection, execute statement, display result, close connection)
Here are the logs (with log_error_verbosity = verbose) :
2019-04-17 11:30:42 CEST;35895;thedbuser;thedb;0;LOG: 0: execute
: SELECT COUNT(1) FROM big_table
2019-04-17 11:30:42 CEST;35895;thedbuser;thedb;0;LOCATION:
exec_execute_message, postgres.c:1959
2019-04-17 11:31:08 CEST;35895;thedbuser;thedb;0;LOG: 0: duration:
25950.908 ms
2019-04-17 11:31:08 CEST;35895;thedbuser;thedb;0;LOCATION:
exec_execute_message, postgres.c:2031
2019-04-17 11:31:20 CEST;37257;thedbuser;thedb;0;LOG: 0: execute
: SELECT COUNT(1) FROM big_table
2019-04-17 11:31:20 CEST;37257;thedbuser;thedb;0;LOCATION:
exec_execute_message, postgres.c:1959
2019-04-17 11:31:32 CEST;37257;thedbuser;thedb;0;LOG: 0: duration:
11459.943 ms
2019-04-17 11:31:32 CEST;37257;thedbuser;thedb;0;LOCATION:
exec_execute_message, postgres.c:2031
2019-04-17 11:32:56 CEST;37324;thedbuser;thedb;0;LOG: 0: statement:
SELECT COUNT(1) FROM big_table;
2019-04-17 11:32:56 CEST;37324;thedbuser;thedb;0;LOCATION:
exec_simple_query, postgres.c:940
2019-04-17 11:33:08 CEST;37324;thedbuser;thedb;0;LOG: 0: duration:
11334.677 ms
2019-04-17 11:33:08 CEST;37313;thedbuser;thedb;0;LOG: 0: statement:
SELECT oid, format_type(oid, NULL) AS typname FROM pg_type WHERE oid IN (20)
ORDER BY oid;
2019-04-17 11:33:08 CEST;37313;thedbuser;thedb;0;LOCATION:
exec_simple_query, postgres.c:940
2019-04-17 11:33:08 CEST;37313;thedbuser;thedb;0;LOG: 0: duration:
0.900 ms
2019-04-17 11:33:08 CEST;37313;thedbuser;thedb;0;LOCATION:
exec_simple_query, postgres.c:1170
I don’t see any difference a part from the query duration. Note that while
monitoring the server I saw that there was parallelism with JDBC program and
PGAdmin4, but not with Dbeaver. And the JDBC driver is the same in both “Basic
JDBC” and DBeaver.
Regards.
Laurent.
De : Andreas Joseph Krogh [mailto:andr...@visena.com]
Envoyé : mercredi 17 avril 2019 11:08
À : pgsql-performance@lists.postgresql.org
Objet : Sv: Pg10 : Client Configuration for Parallelism ?
På onsdag 17. april 2019 kl. 08:30:28, skrev
mailto:laurent.decha...@orange.com>>:
Hi,
I am working on PostgreSQL 10.5 and I have a discrepancy between clients
regarding parallelism feature.
For a simple query (say a simple SELECT COUNT(*) FROM BIG_TABLE), I can see
PostgreSQL use parallelism when the query is launched from psql or PgAdmin4.
However the same query launched with DBeaver (ie connected through JDBC) does
not use parallelism.
SELECT current_setting('max_parallel_workers_per_gather') gives 10 from my
session.
Is there a client configuration that prevents from using parallelism ?
Thanks.
Laurent
Set in postgresql.conf:
log_statement = 'all'
reload settings and check the logs for what statemets are acutally issued.
--
Andreas Joseph Krogh
CTO / Partner - Visena AS
Mobile: +47 909 56 963
andr...@visena.com<mailto:andr...@visena.com>
www.visena.com<https://www.visena.com>
[cid:image001.png@01D4F510.5C6B6150]<https://www.visena.com>
_
Ce message et ses pieces jointes peuvent contenir des informations
confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce
message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages
electroniques etant susceptibles d'alteration,
Orange decline toute responsabilite si ce message a ete altere, deforme ou
falsifie. Merci.
This message and its attachments may contain confidential or privileged
information that may be protected by law;
they should not be distributed, used or copied without authorisation.
If you have received this email in error, please notify the sender and delete
this message and its attachments.
As emails may be altered, Orange is not liable for messages that have been
modified, changed or falsified.
Thank you.
RE: Pg10 : Client Configuration for Parallelism ?
Thanks for the tip. I have compared all settings and they are identical.
Very strange.
-Message d'origine-
De : Andreas Kretschmer [mailto:andr...@a-kretschmer.de]
Envoyé : mercredi 17 avril 2019 10:07
À : pgsql-performance@lists.postgresql.org
Objet : Re: Pg10 : Client Configuration for Parallelism ?
Am 17.04.19 um 08:30 schrieb laurent.decha...@orange.com:
> SELECT current_setting('max_parallel_workers_per_gather') gives 10 from my
> session.
>
> Is there a client configuration that prevents from using parallelism ?
unlikely.
if i were you, i would compare all settings, using the different client
software. (show all, and compare)
Regards, Andreas
--
2ndQuadrant - The PostgreSQL Support Company.
www.2ndQuadrant.com
_
Ce message et ses pieces jointes peuvent contenir des informations
confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce
message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages
electroniques etant susceptibles d'alteration,
Orange decline toute responsabilite si ce message a ete altere, deforme ou
falsifie. Merci.
This message and its attachments may contain confidential or privileged
information that may be protected by law;
they should not be distributed, used or copied without authorisation.
If you have received this email in error, please notify the sender and delete
this message and its attachments.
As emails may be altered, Orange is not liable for messages that have been
modified, changed or falsified.
Thank you.
Sv: Pg10 : Client Configuration for Parallelism ?
På onsdag 17. april 2019 kl. 08:30:28, skrev mailto:laurent.decha...@orange.com>>: Hi,
I am working on PostgreSQL 10.5 and I have a discrepancy between clients
regarding parallelism feature.
For a simple query (say a simple SELECT COUNT(*) FROM BIG_TABLE), I can see
PostgreSQL use parallelism when the query is launched from psql or PgAdmin4.
However the same query launched with DBeaver (ie connected through JDBC) does
not use parallelism.
SELECT current_setting('max_parallel_workers_per_gather') gives 10 from my
session.
Is there a client configuration that prevents from using parallelism ?
Thanks.
Laurent Set in postgresql.conf: log_statement = 'all' reload settings and
check the logs for what statemets are acutally issued. -- Andreas Joseph Krogh
CTO / Partner - Visena AS Mobile: +47 909 56 963 andr...@visena.com
www.visena.com
Re: Pg10 : Client Configuration for Parallelism ?
laurent.decha...@orange.com schrieb am 17.04.2019 um 08:30:
> I am working on PostgreSQL 10.5 and I have a discrepancy between clients
> regarding parallelism feature.
>
> For a simple query (say a simple SELECT COUNT(*) FROM BIG_TABLE), I
> can see PostgreSQL use parallelism when the query is launched from
> psql or PgAdmin4. However the same query launched with DBeaver (ie
> connected through JDBC) does not use parallelism.
>
> SELECT current_setting('max_parallel_workers_per_gather') gives 10
> from my session.
>
> Is there a client configuration that prevents from using parallelism?
Maybe DBeaver wraps the statement for some reason? (I have seen SQL clients do
that)
A CTE would prevent parallelism.
Re: Pg10 : Client Configuration for Parallelism ?
Am 17.04.19 um 08:30 schrieb laurent.decha...@orange.com:
SELECT current_setting('max_parallel_workers_per_gather') gives 10 from my
session.
Is there a client configuration that prevents from using parallelism ?
unlikely.
if i were you, i would compare all settings, using the different client
software. (show all, and compare)
Regards, Andreas
--
2ndQuadrant - The PostgreSQL Support Company.
www.2ndQuadrant.com
Pg10 : Client Configuration for Parallelism ?
Hi,
I am working on PostgreSQL 10.5 and I have a discrepancy between clients
regarding parallelism feature.
For a simple query (say a simple SELECT COUNT(*) FROM BIG_TABLE), I can see
PostgreSQL use parallelism when the query is launched from psql or PgAdmin4.
However the same query launched with DBeaver (ie connected through JDBC) does
not use parallelism.
SELECT current_setting('max_parallel_workers_per_gather') gives 10 from my
session.
Is there a client configuration that prevents from using parallelism ?
Thanks.
Laurent
_
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