[postgis-tickets] [PostGIS] #3561: Regression when PARALLELISM kicks in

[PostGIS]

#3561: Regression when PARALLELISM kicks in
---------------------+---------------------------
 Reporter:  robe     |      Owner:  pramsey
     Type:  defect   |     Status:  new
 Priority:  high     |  Milestone:  PostGIS 2.3.0
Component:  postgis  |    Version:  trunk
 Keywords:           |
---------------------+---------------------------
 So I forced parallelism on on my PostgreSQL 9.6 instance with this:


 {{{
 ALTER SYSTEM set parallel_tuple_cost=0.01;
 ALTER SYSTEM set max_parallel_degree=4;
 ALTER SYSTEM set force_parallel_mode=on;
 ALTER SYSTEM set parallel_setup_cost=100;

 SELECT pg_reload_conf();
 }}}


 and after that I get two regression failures:

 {{{
 regress_index .. failed (diff expected obtained:
 /projects/postgis/tmp/2.3_pg9.6w64/test_59_diff)

 sfcgal/regress_ogc_prep .. failed (diff expected obtained:
 /projects/postgis/tmp/2.3_pg9.6w64/test_119_diff)
 }}}


 The first one I forget what all those things mean so might be just the way
 parallelism is breaking out the work load:


 {{{
 --- regress_index_expected      2015-07-30 14:50:49 -0400
 +++ /projects/postgis/tmp/2.3_pg9.6w64/test_59_out      2016-05-16
 21:28:41 -0400
 @@ -7,10 +7,10 @@
  3618|POINT(130.447205 131.655289)
  7245|POINT(128.10466 130.94133)
  3+=5:true
 -924+=60:true
 -12621+=500:true
 -50000+=600:true
 +924+=60:false:924
 +12621+=500:false:12621
 +50000+=600:false:50000
  expr|3+=5:true
 -expr|924+=60:true
 -expr|12621+=500:true
 -expr|50000+=600:true
 +expr|924+=60:false:924
 +expr|12621+=500:false:12621
 +expr|50000+=600:false:50000
 }}}

 The sfcgal one I guess means we can't have parallelism enabled for all
 tests, have to be selective, which means our regress needs to be modified
 to accomodate parallel testing (I'll flag as separate ticket).


 {{{
 --- sfcgal/regress_ogc_prep_expected    2015-07-30 14:50:46 -0400
 +++ /projects/postgis/tmp/2.3_pg9.6w64/test_119_out     2016-05-16
 21:29:44 -0400
 @@ -1,21 +1,25 @@
 +WARNING:  cannot set parameters during a parallel operation
  intersects099|t
  intersects100|t
  intersects101|t
  intersects102|f
  intersects103|t
  intersects104|f
 +WARNING:  cannot set parameters during a parallel operation
  contains099|t
  contains100|t
  contains101|f
  contains102|f
  contains103|f
  contains104|f
 +WARNING:  cannot set parameters during a parallel operation
  covers099|t
  covers100|t
  covers101|t
  covers102|f
  covers103|t
  covers104|f
 +WARNING:  cannot set parameters during a parallel operation
  containsproperly099|t
  containsproperly100|t
  containsproperly101|f
 }}}

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Ticket URL: <https://trac.osgeo.org/postgis/ticket/3561>
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