debug_print_plan is a GUC controlling whether the plan of a query is logged.
debug_print_plan was added in PostgreSQL 7.1 (commit 6a68f426).
Default
Default value for debug_print_plan is: off
Notes
As far as it's possible to ascertain, debug_print_plan was added in feature commit (commit 6a68f426), in which PostgreSQL's Grand Unified Configuration system was introduced.
Examples
Sample output with an arbitrary query (here an INSERT into a partitioned table):
[2020-08-16 15:10:11 UTC] psql postgres postgres LOG: 00000: statement: INSERT INTO part_parent values(1,'foo') returning *;
[2020-08-16 15:10:11 UTC] psql postgres postgres LOCATION: exec_simple_query, postgres.c:1044
[2020-08-16 15:10:11 UTC] psql postgres postgres LOG: 00000: plan:
[2020-08-16 15:10:11 UTC] psql postgres postgres DETAIL: {PLANNEDSTMT
:commandType 3
:queryId 0
:hasReturning true
:hasModifyingCTE false
:canSetTag true
:transientPlan false
:dependsOnRole false
:parallelModeNeeded false
:jitFlags 0
:planTree
{MODIFYTABLE
:startup_cost 0.00
:total_cost 0.01
:plan_rows 1
:plan_width 86
:parallel_aware false
:parallel_safe false
:plan_node_id 0
:targetlist (
{TARGETENTRY
:expr
{VAR
:varno 1
:varattno 1
:vartype 23
:vartypmod -1
:varcollid 0
:varlevelsup 0
:varnosyn 1
:varattnosyn 1
:location 51
}
:resno 1
:resname id
:ressortgroupref 0
:resorigtbl 16490
:resorigcol 1
:resjunk false
}
{TARGETENTRY
:expr
{VAR
:varno 1
:varattno 2
:vartype 1043
:vartypmod 36
:varcollid 100
:varlevelsup 0
:varnosyn 1
:varattnosyn 2
:location 51
}
:resno 2
:resname val
:ressortgroupref 0
:resorigtbl 16490
:resorigcol 2
:resjunk false
}
)
:qual <>
:lefttree <>
:righttree <>
:initPlan <>
:extParam (b)
:allParam (b)
:operation 3
:canSetTag true
:nominalRelation 1
:rootRelation 1
:partColsUpdated false
:resultRelations (i 1)
:resultRelIndex 0
:rootResultRelIndex 0
:plans (
{RESULT
:startup_cost 0.00
:total_cost 0.01
:plan_rows 1
:plan_width 86
:parallel_aware false
:parallel_safe false
:plan_node_id 1
:targetlist (
{TARGETENTRY
:expr
{CONST
:consttype 23
:consttypmod -1
:constcollid 0
:constlen 4
:constbyval true
:constisnull false
:location 31
:constvalue 4 [ 1 0 0 0 0 0 0 0 ]
}
:resno 1
:resname id
:ressortgroupref 0
:resorigtbl 0
:resorigcol 0
:resjunk false
}
{TARGETENTRY
:expr
{CONST
:consttype 1043
:consttypmod 36
:constcollid 100
:constlen -1
:constbyval false
:constisnull false
:location -1
:constvalue 7 [ 28 0 0 0 102 111 111 ]
}
:resno 2
:resname val
:ressortgroupref 0
:resorigtbl 0
:resorigcol 0
:resjunk false
}
)
:qual <>
:lefttree <>
:righttree <>
:initPlan <>
:extParam (b)
:allParam (b)
:resconstantqual <>
}
)
:withCheckOptionLists <>
:returningLists ((
{TARGETENTRY
:expr
{VAR
:varno 1
:varattno 1
:vartype 23
:vartypmod -1
:varcollid 0
:varlevelsup 0
:varnosyn 1
:varattnosyn 1
:location 51
}
:resno 1
:resname id
:ressortgroupref 0
:resorigtbl 16490
:resorigcol 1
:resjunk false
}
{TARGETENTRY
:expr
{VAR
:varno 1
:varattno 2
:vartype 1043
:vartypmod 36
:varcollid 100
:varlevelsup 0
:varnosyn 1
:varattnosyn 2
:location 51
}
:resno 2
:resname val
:ressortgroupref 0
:resorigtbl 16490
:resorigcol 2
:resjunk false
}
))
:fdwPrivLists (<>)
:fdwDirectModifyPlans (b)
:rowMarks <>
:epqParam 0
:onConflictAction 0
:arbiterIndexes <>
:onConflictSet <>
:onConflictWhere <>
:exclRelRTI 0
:exclRelTlist <>
}
:rtable (
{RTE
:alias <>
:eref
{ALIAS
:aliasname part_parent
:colnames ("id" "val")
}
:rtekind 0
:relid 16490
:relkind p
:rellockmode 3
:tablesample <>
:lateral false
:inh false
:inFromCl false
:requiredPerms 3
:checkAsUser 0
:selectedCols (b 8 9)
:insertedCols (b 8 9)
:updatedCols (b)
:extraUpdatedCols (b)
:securityQuals <>
}
{RTE
:alias <>
:eref
{ALIAS
:aliasname *RESULT*
:colnames <>
}
:rtekind 8
:lateral false
:inh false
:inFromCl false
:requiredPerms 0
:checkAsUser 0
:selectedCols (b)
:insertedCols (b)
:updatedCols (b)
:extraUpdatedCols (b)
:securityQuals <>
}
)
:resultRelations (i 1)
:rootResultRelations (i 1)
:appendRelations <>
:subplans <>
:rewindPlanIDs (b)
:rowMarks <>
:relationOids (o 16490)
:invalItems <>
:paramExecTypes (o 0)
:utilityStmt <>
:stmt_location 0
:stmt_len 52
}
[2020-08-16 15:10:11 UTC] psql postgres postgres LOCATION: elog_node_display, print.c:85
References
- PostgreSQL documentation: debug_print_plan