Project

General

Profile

Task #884

Updated by Aaron Marcuse-Kubitza about 10 years ago

h3. issue 

 * see the following @pg_stat_activity@ snapshots snapshot (note the @EXPLAIN@ output below each query): 
 <pre><code class="SQL"> 
 /*NVS.StemObservation*/ 	 CREATE TEMP TABLE "stemobservation_pkeys" AS 
 SELECT 
 "in#11"."row_num" 
 , "stemobservation"."stemobservation_id" AS "out.stemobservation_id" 
 FROM "in#11" 
 JOIN "stemobservation" ON COALESCE("stemobservation"."height_m", CAST('NaN' AS double precision)) = COALESCE("in#11"."NVS.StemObservation.Height::double", CAST('NaN' AS double precision)) 
 /* EXPLAIN: 
 Merge Join    (cost=1045217.21..95909185.15 rows=6323041431 width=8) 
   Merge Cond: ((COALESCE(stemobservation.height_m, 'NaN'::double precision)) = (COALESCE("in#11"."NVS.StemObservation.Height::double", 'NaN'::double precision))) 
   ->    Sort    (cost=30039.56..30492.76 rows=181279 width=12) 
         Sort Key: (COALESCE(stemobservation.height_m, 'NaN'::double precision)) 
         ->    Seq Scan on stemobservation    (cost=0.00..14206.79 rows=181279 width=12) 
   ->    Materialize    (cost=1015177.64..1050057.81 rows=6976033 width=12) 
         ->    Sort    (cost=1015177.64..1032617.73 rows=6976033 width=12) 
               Sort Key: (COALESCE("in#11"."NVS.StemObs 

 /*CVS.taxon_observation.***/ 	 CREATE TEMP TABLE "location_pkeys" AS 
 SELECT 
 "in#5"."row_num" 
 , "location"."location_id" AS "out.location_id" 
 FROM "in#5" 
 JOIN "location" ON ("location"."accesslevel" = "in#5"."CVS.taxon_observation.**.accessRights::accesslevel" OR ("location"."accesslevel" IS NULL AND "in#5"."CVS.taxon_observation.**.accessRights::accesslevel" IS NULL)) 
 /* EXPLAIN: 
 Nested Loop    (cost=0.00..83049883712.45 rows=27683225000 width=8) 
   Join Filter: ((location.accesslevel = "in#5"."CVS.taxon_observation.**.accessRights::accesslevel") OR ((location.accesslevel IS NULL) AND ("in#5"."CVS.taxon_observation.**.accessRights::accesslevel" IS NULL))) 
   ->    Seq Scan on location    (cost=0.00..175778.45 rows=5536645 width=8) 
   ->    Materialize    (cost=0.00..35434.00 rows=1000000 width=8) 
         ->    Seq Scan on "in#5"    (cost=0.00..30434.00 rows=1000000 width=8) 
 */ 
 </code></pre><pre><code class="SQL"> 
 /*ARIZ.omoccurrences*/ 	 CREATE TEMP TABLE "location_pkeys" AS 
 SELECT 
 "in#6"."occurrenceID" 
 , "location"."location_id" AS "out.location_id" 
 FROM "in#6" 
 JOIN "location" ON COALESCE("location"."elevation_m", CAST('NaN' AS double precision)) = COALESCE("in#6"."_alt(1=verbatimElevation, 2=_avg(1=minimumElevat.result::double", CAST('NaN' AS double precision)) 
 /* EXPLAIN: 
 Merge Join    (cost=52039.20..3508151.98 rows=230343442 width=8) 
   Merge Cond: ((COALESCE(location.elevation_m, 'NaN'::double precision)) = (COALESCE("in#6"."_alt(1=verbatimElevation, 2=_avg(1=minimumElevat.result::double", 'NaN'::double precision))) 
   ->    Sort    (cost=23780.86..24261.44 rows=192230 width=12) 
         Sort Key: (COALESCE(location.elevation_m, 'NaN'::double precision)) 
         ->    Seq Scan on location    (cost=0.00..6910.30 rows=192230 width=12) 
   ->    Sort    (cost=28258.34..28857.47 rows=239654 width=12) 
         Sort Key: (COALESCE("in#6"."_alt(1=verbatimElevation, 2=_avg(1=minimumElevat.result::double", 'NaN'::double precision)) 
         - 
 */ 
 </code></pre> 
 * this is separate from the disk space leak (#887), which is also associated with the above queries but caused by more than just the fact that it's using sorts 

 h3. fix 

 * set query planner settings to prevent it from using sorts where they shouldn't be used

Back