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Improve EXPLAIN to print the grouping columns in Agg and Group nodes.

Browse Source 
Per request from Kevin Grittner.
pull/6/head
Tom Lane 12 years ago
parent 8693559cac
commit f26099057a
6 changed files with 92 additions and 30 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 13
      doc/src/sgml/ref/explain.sgml
  2. 77
      src/backend/commands/explain.c
  3. 6
      src/test/regress/expected/aggregates.out
  4. 9
      src/test/regress/expected/matview.out
  5. 10
      src/test/regress/expected/union.out
  6. 7
      src/test/regress/expected/window.out

13
doc/src/sgml/ref/explain.sgml
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@ -395,13 +395,14 @@ PREPARE query(int, int) AS SELECT sum(bar) FROM test
EXPLAIN ANALYZE EXECUTE query(100, 200);
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------
HashAggregate (cost=39.53..39.53 rows=1 width=8) (actual time=0.661..0.672 rows=7 loops=1)
-> Index Scan using test_pkey on test (cost=0.00..32.97 rows=1311 width=8) (actual time=0.050..0.395 rows=99 loops=1)
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------
HashAggregate (cost=9.54..9.54 rows=1 width=8) (actual time=0.156..0.161 rows=11 loops=1)
Group Key: foo
-> Index Scan using test_pkey on test (cost=0.29..9.29 rows=50 width=8) (actual time=0.039..0.091 rows=99 loops=1)
Index Cond: ((id > $1) AND (id < $2))
Total runtime: 0.851 ms
(4 rows)
Total runtime: 0.225 ms
(5 rows)
</programlisting>
</para>

77
src/backend/commands/explain.c
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@ -76,9 +76,13 @@ static void show_sort_keys(SortState *sortstate, List *ancestors,
ExplainState *es);
static void show_merge_append_keys(MergeAppendState *mstate, List *ancestors,
ExplainState *es);
static void show_sort_keys_common(PlanState *planstate,
int nkeys, AttrNumber *keycols,
List *ancestors, ExplainState *es);
static void show_agg_keys(AggState *astate, List *ancestors,
ExplainState *es);
static void show_group_keys(GroupState *gstate, List *ancestors,
ExplainState *es);
static void show_sort_group_keys(PlanState *planstate, const char *qlabel,
int nkeys, AttrNumber *keycols,
List *ancestors, ExplainState *es);
static void show_sort_info(SortState *sortstate, ExplainState *es);
static void show_hash_info(HashState *hashstate, ExplainState *es);
static void show_instrumentation_count(const char *qlabel, int which,
@ -1341,7 +1345,14 @@ ExplainNode(PlanState *planstate, List *ancestors,
planstate, es);
break;
case T_Agg:
show_agg_keys((AggState *) planstate, ancestors, es);
show_upper_qual(plan->qual, "Filter", planstate, ancestors, es);
if (plan->qual)
show_instrumentation_count("Rows Removed by Filter", 1,
planstate, es);
break;
case T_Group:
show_group_keys((GroupState *) planstate, ancestors, es);
show_upper_qual(plan->qual, "Filter", planstate, ancestors, es);
if (plan->qual)
show_instrumentation_count("Rows Removed by Filter", 1,
@ -1693,9 +1704,9 @@ show_sort_keys(SortState *sortstate, List *ancestors, ExplainState *es)
{
Sort *plan = (Sort *) sortstate->ss.ps.plan;
show_sort_keys_common((PlanState *) sortstate,
plan->numCols, plan->sortColIdx,
ancestors, es);
show_sort_group_keys((PlanState *) sortstate, "Sort Key",
plan->numCols, plan->sortColIdx,
ancestors, es);
}
/*
@ -1707,14 +1718,56 @@ show_merge_append_keys(MergeAppendState *mstate, List *ancestors,
{
MergeAppend *plan = (MergeAppend *) mstate->ps.plan;
show_sort_keys_common((PlanState *) mstate,
plan->numCols, plan->sortColIdx,
ancestors, es);
show_sort_group_keys((PlanState *) mstate, "Sort Key",
plan->numCols, plan->sortColIdx,
ancestors, es);
}
/*
* Show the grouping keys for an Agg node.
*/
static void
show_agg_keys(AggState *astate, List *ancestors,
ExplainState *es)
{
Agg *plan = (Agg *) astate->ss.ps.plan;
if (plan->numCols > 0)
{
/* The key columns refer to the tlist of the child plan */
ancestors = lcons(astate, ancestors);
show_sort_group_keys(outerPlanState(astate), "Group Key",
plan->numCols, plan->grpColIdx,
ancestors, es);
ancestors = list_delete_first(ancestors);
}
}
/*
* Show the grouping keys for a Group node.
*/
static void
show_group_keys(GroupState *gstate, List *ancestors,
ExplainState *es)
{
Group *plan = (Group *) gstate->ss.ps.plan;
/* The key columns refer to the tlist of the child plan */
ancestors = lcons(gstate, ancestors);
show_sort_group_keys(outerPlanState(gstate), "Group Key",
plan->numCols, plan->grpColIdx,
ancestors, es);
ancestors = list_delete_first(ancestors);
}
/*
* Common code to show sort/group keys, which are represented in plan nodes
* as arrays of targetlist indexes
*/
static void
show_sort_keys_common(PlanState *planstate, int nkeys, AttrNumber *keycols,
List *ancestors, ExplainState *es)
show_sort_group_keys(PlanState *planstate, const char *qlabel,
int nkeys, AttrNumber *keycols,
List *ancestors, ExplainState *es)
{
Plan *plan = planstate->plan;
List *context;
@ -1748,7 +1801,7 @@ show_sort_keys_common(PlanState *planstate, int nkeys, AttrNumber *keycols,
result = lappend(result, exprstr);
}
ExplainPropertyList("Sort Key", result, es);
ExplainPropertyList(qlabel, result, es);
}
/*

6
src/test/regress/expected/aggregates.out
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@ -659,12 +659,13 @@ explain (costs off)
QUERY PLAN
---------------------------------------------------------------------
HashAggregate
Group Key: $0
InitPlan 1 (returns $0)
-> Limit
-> Index Only Scan Backward using tenk1_unique2 on tenk1
Index Cond: (unique2 IS NOT NULL)
-> Result
(6 rows)
(7 rows)
select distinct max(unique2) from tenk1;
max
@ -806,6 +807,7 @@ explain (costs off)
QUERY PLAN
----------------------------------------------------------------------------------------------
HashAggregate
Group Key: $0, $1
InitPlan 1 (returns $0)
-> Limit
-> Merge Append
@ -831,7 +833,7 @@ explain (costs off)
-> Index Only Scan Backward using minmaxtest3i on minmaxtest3 minmaxtest3_1
Index Cond: (f1 IS NOT NULL)
-> Result
(26 rows)
(27 rows)
select distinct min(f1), max(f1) from minmaxtest;
min | max

9
src/test/regress/expected/matview.out
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@ -22,8 +22,9 @@ EXPLAIN (costs off)
QUERY PLAN
---------------------
HashAggregate
Group Key: type
-> Seq Scan on t
(2 rows)
(3 rows)
CREATE MATERIALIZED VIEW tm AS SELECT type, sum(amt) AS totamt FROM t GROUP BY type WITH NO DATA;
SELECT relispopulated FROM pg_class WHERE oid = 'tm'::regclass;
@ -59,8 +60,9 @@ EXPLAIN (costs off)
Sort
Sort Key: t.type
-> HashAggregate
Group Key: t.type
-> Seq Scan on t
(4 rows)
(5 rows)
CREATE MATERIALIZED VIEW tvm AS SELECT * FROM tv ORDER BY type;
SELECT * FROM tvm;
@ -82,8 +84,9 @@ EXPLAIN (costs off)
---------------------------
Aggregate
-> HashAggregate
Group Key: t.type
-> Seq Scan on t
(3 rows)
(4 rows)
CREATE MATERIALIZED VIEW tvvm AS SELECT * FROM tvv;
CREATE VIEW tvvmv AS SELECT * FROM tvvm;

10
src/test/regress/expected/union.out
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@ -494,12 +494,13 @@ explain (costs off)
QUERY PLAN
---------------------------------------------------
HashAggregate
Group Key: ((t1.a || t1.b))
-> Append
-> Index Scan using t1_ab_idx on t1
Index Cond: ((a || b) = 'ab'::text)
-> Index Only Scan using t2_pkey on t2
Index Cond: (ab = 'ab'::text)
(6 rows)
(7 rows)
reset enable_seqscan;
reset enable_indexscan;
@ -552,17 +553,18 @@ SELECT * FROM
SELECT 2 AS t, 4 AS x) ss
WHERE x < 4
ORDER BY x;
QUERY PLAN
--------------------------------
QUERY PLAN
--------------------------------------------------------
Sort
Sort Key: ss.x
-> Subquery Scan on ss
Filter: (ss.x < 4)
-> HashAggregate
Group Key: (1), (generate_series(1, 10))
-> Append
-> Result
-> Result
(8 rows)
(9 rows)
SELECT * FROM
(SELECT 1 AS t, generate_series(1,10) AS x

7
src/test/regress/expected/window.out
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@ -619,12 +619,13 @@ explain (costs off)
select first_value(max(x)) over (), y
from (select unique1 as x, ten+four as y from tenk1) ss
group by y;
QUERY PLAN
-------------------------------
QUERY PLAN
---------------------------------------------
WindowAgg
-> HashAggregate
Group Key: (tenk1.ten + tenk1.four)
-> Seq Scan on tenk1
(3 rows)
(4 rows)
-- test non-default frame specifications
SELECT four, ten,

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