Re: ERROR: XX000: cannot update SecondarySnapshot during a paralleloperation

On 3/14/19 6:14 AM, Julien Rouhaud wrote:
> On Thu, Mar 14, 2019 at 1:20 PM fuzk <fuzk80_76@163.com> wrote:
>>
>> Dear Adrian,
>>
>> My setting is as following.
>>
>> max_parallel_workers_per_gather=32
>>
>> I am looking forward to hearing from you.
> 
> What version of postgres and what version of postgis are you using ?
> 
>> At 2019-03-13 22:31:11, "Adrian Klaver" <adrian.klaver@aklaver.com> wrote:
>>> On 3/12/19 7:54 PM, fuzk wrote:
>>>> 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 not familiar at all with geography, but if I read the code
> correctly, ST_Length / geography_length will call
> spheroid_init_from_srid(), which eventuallly calls GetProj4StringSPI()
> that run a query using SPI.  I'm not sure why exactly
> GetLatestSnapshot() is called here, or if SPI is really allowed in
> parallel workers, but that's the problem here apparently.  I'm adding
> Paul as he'll probably have a way better answer than me.
> 

https://trac.osgeo.org/postgis/ticket/4129
"Cannot update SecondarySnapshot during a parallel operation"

-- 
Adrian Klaver
adrian.klaver@aklaver.com