Tom,
Ok, but how about reading from temporary tables? We could mark the function as
"PARALLEL SAFE” instead of "PARALLEL RESTRICTED” in this case if it’s
important. Actually, I rewrote the function without temp tables access but
that’s not helpful - the function marked as "PARALLEL SAFE” is not
mobigroup writes:
>> Perhaps you didn't define it as PARALLEL SAFE.
> The function is marked as "PARALLEL RESTRICTED” because it’s uses temp tables
> (and I tested it as PARALLEL SAFE with the same result… parallelisation
> doesn’t work anyway).
If it writes into temp tables then it can't be r
Thanks for the ideas, I tested them:
>
> The essential question here is when the function is executed, so you should
> use
> EXPLAIN (VERBOSE) to see that.
Append (cost=0.00..5.12 rows=4 width=32)
-> Gather (cost=0.00..1.26 rows=1 width=32)
Output: plpgsql_function(...)
Work
On Tue, 2020-12-01 at 14:38 +0700, mobigroup wrote:
> I have strange behaviour when EXPLAIN returns parallel execution plan but the
> query execution is not parallel. The query looks as
>
> SELECT
> plpgsql_function(...parameters…)
> FROM table as t
> WHERE id=
Hi,
I have strange behaviour when EXPLAIN returns parallel execution plan but the
query execution is not parallel. The query looks as
SELECT
plpgsql_function(...parameters…)
FROM table as t
WHERE id=1
UNION ALL
SELECT
plpgsql_functi
ry is duplicated and not referring to multiple
queries issued.
The only difference is obviosly the pid and client_addr, that is
populated in any of the connections but the first one.
client_addr being different would seem to indicate that this is
something other then parallel query.
Hi there, we are running postgresql 10.5 on a centos 7 server.
We're seeing multiple connections (in pg_stat_activity) from our
application with the same query , same user, same application_name, same
query_start etc.
We are 100% sure the query is duplicated and not referring to multiple
queries
Ok, to close this thread. The problem is, that plpgsql function do seem to
return data using a cursor. That fact is disabling parallel execution. So
if we instead hand over the SQL to a function with e.g. a python body, then
parallel execution is happening, because the data is first assembled in
me
ah, and for completeness the simple python function I use for the test:
create or replace function reports.generic_query_python(_sql text)
RETURNS SETOF record
LANGUAGE 'plpythonu'
PARALLEL SAFE
COST 100
VOLATILE
ROWS 5000
AS $BODY$
return plpy.execute( _sql )
$BODY$;
Michael Krü
Dear all,
still same behavior with Postgres 10.2 ...
Just as a reminder that the issue still exists.
Regards,
Michael
Andreas Kretschmer schrieb am Di., 6. Feb. 2018
um 08:35 Uhr:
> Hi,
>
>
> Am 06.02.2018 um 08:24 schrieb Michael Krüger:
> > create or replace function reports.generic_query(_
: Trying to the behavior of a parallel query with with a change in
the transaction isolation mode
Luis Carril wrote:
> The transaction isolation level is serializable. This situation does not
> normally arise, because parallel query plans are not generated when the
> transaction isolat
Luis Carril wrote:
> The transaction isolation level is serializable. This situation does not
> normally arise, because parallel query plans are not generated when the
> transaction isolation level is serializable. However, it can happen if the
> transaction isolation level i
Hi all,
I am trying to verify if during a transaction a parallel plan ca be
generated but later only a sequential one is executed.
The documentation says the following (in
https://www.postgresql.org/docs/9.6/static/when-can-parallel-query-be-used.html):
---
Even when parallel
Hi,
Am 06.02.2018 um 08:24 schrieb Michael Krüger:
create or replace function reports.generic_query(_sql text)
RETURNS SETOF record
LANGUAGE 'plpgsql'
PARALLEL SAFE
COST 100
there is an other parameter, parallel_setup_cost, with default = 1000. I
think, you should set this parameter
Dear community,
I need a bit of advice on parallel query execution.
I have a table with roughly 2 million rows in it. These rows are
distributed over a set of IDs. Therefore I can group my rows based on the
ID set.
If I query the table directly like this:
select mediatrunkid,count(*)::numeric
n be started by a single Gather or Gather
> Merge node.
>
> I am not able to understand gather and gather merge node.
>
> With parallel query in picture, there are two new types of nodes
introduced in postgresql 10 viz, Gather node and other is Gather-Merge
node.
Now, if seq-sca
Hi All,
I was reading about parallel queries in postgresql 10.
I came across the property max_parallel_workers_per_gather. It sets the
maximum number of workers that can be started by a single Gather or Gather
Merge node.
I am not able to understand gather and gather merge node.
What is the dif
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