[postgis-tickets] [PostGIS] #4129: Cannot update SecondarySnapshot during a parallel operation

[PostGIS]

#4129: Cannot update SecondarySnapshot during a parallel operation
----------------------------------------+---------------------------
 Reporter:  davidp                      |      Owner:  pramsey
     Type:  defect                      |     Status:  new
 Priority:  high                        |  Milestone:  PostGIS 2.4.5
Component:  postgis                     |    Version:  2.4.x
 Keywords:  SecondarySnapshot parallel  |
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 Hi,
 since we upgraded our Postgres/Postgis stack to version 10/2.4 this error
 starts to appear in our log:

 **ERROR: cannot update SecondarySnapshot during a parallel operation**

 Most often in this context:


 {{{
 SQL statement: "SELECT proj4text FROM public.spatial_ref_sys WHERE srid =
 5514 LIMIT 1"
 }}}


 or


 {{{
 SQL statement "SELECT TRUE" PL/pgSQL function
 _st_intersects(geometry,raster,integer)
 }}}


 There are many diferent sources of this error (PHP, Python, Mapnik), so i
 thing, there is marginal chance to be caused by our code (SQL statements).
 When i wrap problematic statements into PL/pgSQL function (which are
 parallel restricted by default), then this error disappear. So my
 suspicion falls on PostGIS functions and how they behave in PostgreSQL
 parallel mode.

 For now i thing there is issue in these PostGIS functions:
   - ST_Transform(geometry, int) which executes "select proj4text
 from..."\\
   - ST_Intersects(geometry, raster)

 Our system info is:


   - PostgreSQL 10.3 (Debian 10.3-1.pgdg90+1) on x86_64-pc-linux-gnu,
 compiled by gcc (Debian 6.3.0-18+deb9u1) 6.3.0 20170516, 64-bit
   - POSTGIS="2.4.4 r16526" PGSQL="100" GEOS="3.5.1-CAPI-1.9.1 r4246"
 PROJ="Rel. 4.9.3, 15 August 2016" GDAL="GDAL 2.1.2, released 2016/10/24"
 LIBXML="2.9.4" LIBJSON="0.12.1" LIBPROTOBUF="1.2.1" RASTER

 And PostreSQL cluster resides behind PGBouncer in session pooling mode.

 Best Regards, David

-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/4129>
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