Index not used - Mailing list pgsql-performance

Hello,
 
I've a basic table with about 100K rows:
 


CREATE TABLE "public"."push_topic" (
 "id" Serial PRIMARY KEY,
 "guid" public.push_guid NOT NULL,
 "authenticatorsending" Varchar(32) NOT NULL,
 "authenticatorsubscription" Varchar(32) NOT NULL,
 "countpushed" Integer NOT NULL,
 "datecreated" timestamp NOT NULL,
 "datelastpush" timestamp
)
CREATE UNIQUE INDEX push_topic_idx_topicguid ON push_topic
  USING btree (guid)


 
When I query this through pgsql, the queries are fast as expected.

This is the query:

select * from push_topic where guid = 'DD748CCD-B8A4-3B9F-8F60-67F1F673CFE5'

And the plan:



Index Scan using push_topic_idx_topicguid on push_topic  (cost=0.42..8.44 rows=1 width=103) (actual time=0.117..0.121
rows=1loops=1) 
  Index Cond: ((guid)::bpchar = 'DD748CCD-B8A4-3B9F-8F60-67F1F673CFE5'::bpchar)
  Buffers: shared hit=3 read=1
Total runtime: 0.191 ms



However when I run the exact query through a different application (CodeSynthesis ORM) the query is very slow (~ 115ms
logged)
I noted this is due to a sequential scan happening on the table instead of an index scan.

This is query plan in the log file:



LOG:  plan:
DETAIL:     {PLANNEDSTMT
       :commandType 1
       :queryId 0
       :hasReturning false
       :hasModifyingCTE false
       :canSetTag true
       :transientPlan false
       :planTree
          {SEQSCAN
          :startup_cost 0.00
          :total_cost 2877.58
          :plan_rows 429
          :plan_width 103
          :targetlist (
             {TARGETENTRY
             :expr
                {VAR
                :varno 1
                :varattno 1
                :vartype 23
                :vartypmod -1
                :varcollid 0
                :varlevelsup 0
                :varnoold 1
                :varoattno 1
                :location 7
                }
             :resno 1
             :resname id
             :ressortgroupref 0
             :resorigtbl 16393
             :resorigcol 1
             :resjunk false
             }
             {TARGETENTRY
             :expr
                {VAR
                :varno 1
                :varattno 2
                :vartype 16385
                :vartypmod -1
                :varcollid 100
                :varlevelsup 0
                :varnoold 1
                :varoattno 2
                :location 26
                }
             :resno 2
             :resname guid
             :ressortgroupref 0
             :resorigtbl 16393
             :resorigcol 2
             :resjunk false
             }
             {TARGETENTRY
             :expr
                {VAR
                :varno 1
                :varattno 3
                :vartype 1043
                :vartypmod 36
                :varcollid 100
                :varlevelsup 0
                :varnoold 1
                :varoattno 3
                :location 47
                }
             :resno 3
             :resname authenticatorsending
             :ressortgroupref 0
             :resorigtbl 16393
             :resorigcol 3
             :resjunk false
             }
             {TARGETENTRY
             :expr
                {VAR
                :varno 1
                :varattno 4
                :vartype 1043
                :vartypmod 36
                :varcollid 100
                :varlevelsup 0
                :varnoold 1
                :varoattno 4
                :location 84
                }
             :resno 4
             :resname authenticatorsubscription
             :ressortgroupref 0
             :resorigtbl 16393
             :resorigcol 4
             :resjunk false
             }
             {TARGETENTRY
             :expr
                {VAR
                :varno 1
                :varattno 5
                :vartype 23
                :vartypmod -1
                :varcollid 0
                :varlevelsup 0
                :varnoold 1
                :varoattno 5
                :location 126
                }
             :resno 5
             :resname countpushed
             :ressortgroupref 0
             :resorigtbl 16393
             :resorigcol 5
             :resjunk false
             }
             {TARGETENTRY
             :expr
                {VAR
                :varno 1
                :varattno 6
                :vartype 1114
                :vartypmod -1
                :varcollid 0
                :varlevelsup 0
                :varnoold 1
                :varoattno 6
                :location 154
                }
             :resno 6
             :resname datecreated
             :ressortgroupref 0
             :resorigtbl 16393
             :resorigcol 6
             :resjunk false
             }
             {TARGETENTRY
             :expr
                {VAR
                :varno 1
                :varattno 7
                :vartype 1114
                :vartypmod -1
                :varcollid 0
                :varlevelsup 0
                :varnoold 1
                :varoattno 7
                :location 182
                }
             :resno 7
             :resname datelastpush
             :ressortgroupref 0
             :resorigtbl 16393
             :resorigcol 7
             :resjunk false
             }
          )
          :qual (
             {OPEXPR
             :opno 98
             :opfuncid 67
             :opresulttype 16
             :opretset false
             :opcollid 0
             :inputcollid 100
             :args (
                {FUNCEXPR
                :funcid 401
                :funcresulttype 25
                :funcretset false
                :funcvariadic false
                :funcformat 2
                :funccollid 100
                :inputcollid 100
                :args (
                   {VAR
                   :varno 1
                   :varattno 2
                   :vartype 16385
                   :vartypmod -1
                   :varcollid 100
                   :varlevelsup 0
                   :varnoold 1
                   :varoattno 2
                   :location 234
                   }
                )
                :location -1
                }
                {CONST
                :consttype 25
                :consttypmod -1
                :constcollid 100
                :constlen -1
                :constbyval false
                :constisnull false
                :location -1
                :constvalue 40 [ -96 0 0 0 48 48 53 51 54 49 69 56 45 51 51 69 65
                45 49 70 48 69 45 66 50 49 55 45 67 57 49 66 52 65 67 55 66 67 69
                54 ]
                }
             )
             :location 254
             }
          )
          :lefttree <>
          :righttree <>
          :initPlan <>
          :extParam (b)
          :allParam (b)
          :scanrelid 1
          }
       :rtable (
          {RTE
          :alias <>
          :eref
             {ALIAS
             :aliasname push_topic
             :colnames ("id" "guid" "authenticatorsending" "authenticatorsubscript
             ion" "countpushed" "datecreated" "datelastpush")
             }
          :rtekind 0
          :relid 16393
          :relkind r
          :lateral false
          :inh false
          :inFromCl true
          :requiredPerms 2
          :checkAsUser 0
          :selectedCols (b 9 10 11 12 13 14 15)
          :modifiedCols (b)
          }
       )
       :resultRelations <>
       :utilityStmt <>
       :subplans <>
       :rewindPlanIDs (b)
       :rowMarks <>
       :relationOids (o 16393)
       :invalItems <>
       :nParamExec 0
       }

STATEMENT:  SELECT "push_topic"."id", "push_topic"."guid", "push_topic"."authenticatorsending",
"push_topic"."authenticatorsubscription","push_topic"."countpushed", "push_topic"."datecreated",
"push_topic"."datelastpush"FROM "push_topic" WHERE "push_topic"."guid" = $1 
LOG:  duration: 115.498 ms  execute query_mc_push_database_Topic: SELECT "push_topic"."id", "push_topic"."guid",
"push_topic"."authenticatorsending","push_topic"."authenticatorsubscription", "push_topic"."countpushed",
"push_topic"."datecreated","push_topic"."datelastpush" FROM "push_topic" WHERE "push_topic"."guid" = $1 




Any idea how to solve this ?

Thank you

Meike