Re:Re: ERROR: XX000: cannot update SecondarySnapshot during a parallel operation

When I set max_parallel_workers_per_gather=0, the select statement can execute successfully. The problem has been solved. Thank you all very much. Alan

At 2019-03-14 22:29:24, "Adrian Klaver" <adrian(dot)klaver(at)aklaver(dot)com> wrote:
>On 3/13/19 10:54 PM, fuzk wrote:
>> Dear Adrian,
>>
>> My setting is as following.
>>
>> max_parallel_workers_per_gather=32
>
>Not sure if it is possible without affecting other operations, but you
>could set the above to 0 to temporarily disable parallel queries and see
>if that eliminates the error.
>
>Also see:
>
>https://trac.osgeo.org/postgis/ticket/4129
>
>>
>> I am looking forward to hearing from you.
>>
>> Many thanks
>> Alan.
>>
>>
>>
>>
>>
>>
>>
>> At 2019-03-13 22:31:11, "Adrian Klaver" <adrian(dot)klaver(at)aklaver(dot)com> wrote:
>>>On 3/12/19 7:54 PM, fuzk wrote:
>>>> Dear Sir/Madam
>>>>
>>>> I got an error when I execute the following select sentence.
>>>> Would you please solve the problem for me?
>>>
>>>What version of Postgres?
>>>
>>>> Thank you .
>>>>
>>>> Alan Fu.
>>>>
>>>> postgres=# \set VERBOSITY verbose
>>>> postgres=# SELECT
>>>> round(cast(coalesce(sum(ST_length(geography(geometry)))/1000,0) as
>>>> NUMERIC),4)||'KM' field_value from had_link;
>>>>
>>>> ERROR: XX000: cannot update SecondarySnapshot during a parallel operation
>>>> CONTEXT: SQL statement "SELECT proj4text FROM public.spatial_ref_sys
>>>> WHERE srid = 4326 LIMIT 1"
>>>> parallel worker
>>>> LOCATION: GetLatestSnapshot, snapmgr.c:387
>>>
>>>I'm guessing ST_length is not parallel safe.
>>>
>>>What is your setting for?:
>>>
>>>max_parallel_workers_per_gather
>>>
>>>>
>>>>
>>>
>>>
>>>--
>>>Adrian Klaver
>>>adrian(dot)klaver(at)aklaver(dot)com
>>
>>
>>
>
>
>--
>Adrian Klaver
>adrian(dot)klaver(at)aklaver(dot)com