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Fix force_parallel_mode to work as intended. #1287

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Fix force_parallel_mode to work as intended. #1287

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2 changes: 2 additions & 0 deletions src/backend/optimizer/plan/planner.c
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Original file line number Diff line number Diff line change
Expand Up @@ -593,6 +593,8 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
{
Path *cheapest_partial_path;
cheapest_partial_path = linitial(final_rel->partial_pathlist);
if (force_parallel_mode == FORCE_PARALLEL_ON)
final_rel->pathlist = NIL;
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@yjhjstz yjhjstz Aug 3, 2025

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if partial_pathlist == NIL，should not final_rel->pathlist = NIL; ?

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@avamingli avamingli Aug 4, 2025

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pathlist can not be empty- this will trigger a 'could not derive a plan for query' failure.

add_path(final_rel, cheapest_partial_path, root);
set_cheapest(final_rel);
}
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4 changes: 2 additions & 2 deletions src/test/regress/expected/incremental_sort.out
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Expand Up @@ -589,7 +589,6 @@ select explain_analyze_without_memory('select * from (select * from t order by a
Optimizer: Postgres query optimizer
(13 rows)

reset max_parallel_workers_per_gather;
select jsonb_pretty(explain_analyze_inc_sort_nodes_without_memory('select * from (select * from t order by a) s order by a, b limit 55'));
jsonb_pretty
-------------------------------------------------
Expand Down Expand Up @@ -626,6 +625,7 @@ select jsonb_pretty(explain_analyze_inc_sort_nodes_without_memory('select * from
]
(1 row)

reset max_parallel_workers_per_gather;
select explain_analyze_inc_sort_nodes_verify_invariants('select * from (select * from t order by a) s order by a, b limit 55');
explain_analyze_inc_sort_nodes_verify_invariants
--------------------------------------------------
Expand Down Expand Up @@ -815,7 +815,6 @@ select explain_analyze_without_memory('select * from (select * from t order by a
Optimizer: Postgres query optimizer
(14 rows)

reset max_parallel_workers_per_gather;
select jsonb_pretty(explain_analyze_inc_sort_nodes_without_memory('select * from (select * from t order by a) s order by a, b limit 70'));
jsonb_pretty
-------------------------------------------------
Expand Down Expand Up @@ -861,6 +860,7 @@ select jsonb_pretty(explain_analyze_inc_sort_nodes_without_memory('select * from
]
(1 row)

reset max_parallel_workers_per_gather;
select explain_analyze_inc_sort_nodes_verify_invariants('select * from (select * from t order by a) s order by a, b limit 70');
explain_analyze_inc_sort_nodes_verify_invariants
--------------------------------------------------
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4 changes: 2 additions & 2 deletions src/test/regress/expected/incremental_sort_optimizer.out
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Expand Up @@ -560,14 +560,14 @@ select explain_analyze_without_memory('select * from (select * from t order by a
Optimizer: Pivotal Optimizer (GPORCA)
(9 rows)

reset max_parallel_workers_per_gather;
select jsonb_pretty(explain_analyze_inc_sort_nodes_without_memory('select * from (select * from t order by a) s order by a, b limit 55'));
jsonb_pretty
--------------
[ +
]
(1 row)

reset max_parallel_workers_per_gather;
select explain_analyze_inc_sort_nodes_verify_invariants('select * from (select * from t order by a) s order by a, b limit 55');
explain_analyze_inc_sort_nodes_verify_invariants
--------------------------------------------------
Expand Down Expand Up @@ -743,14 +743,14 @@ select explain_analyze_without_memory('select * from (select * from t order by a
Optimizer: Pivotal Optimizer (GPORCA)
(10 rows)

reset max_parallel_workers_per_gather;
select jsonb_pretty(explain_analyze_inc_sort_nodes_without_memory('select * from (select * from t order by a) s order by a, b limit 70'));
jsonb_pretty
--------------
[ +
]
(1 row)

reset max_parallel_workers_per_gather;
select explain_analyze_inc_sort_nodes_verify_invariants('select * from (select * from t order by a) s order by a, b limit 70');
explain_analyze_inc_sort_nodes_verify_invariants
--------------------------------------------------
Expand Down
4 changes: 2 additions & 2 deletions src/test/regress/sql/incremental_sort.sql
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Expand Up @@ -147,8 +147,8 @@ select * from (select * from t order by a) s order by a, b limit 55;
-- Test EXPLAIN ANALYZE with only a fullsort group.
set max_parallel_workers_per_gather = 0;
select explain_analyze_without_memory('select * from (select * from t order by a) s order by a, b limit 55');
reset max_parallel_workers_per_gather;
select jsonb_pretty(explain_analyze_inc_sort_nodes_without_memory('select * from (select * from t order by a) s order by a, b limit 55'));
reset max_parallel_workers_per_gather;
select explain_analyze_inc_sort_nodes_verify_invariants('select * from (select * from t order by a) s order by a, b limit 55');
delete from t;

Expand Down Expand Up @@ -181,8 +181,8 @@ rollback;
-- Test EXPLAIN ANALYZE with both fullsort and presorted groups.
set max_parallel_workers_per_gather = 0;
select explain_analyze_without_memory('select * from (select * from t order by a) s order by a, b limit 70');
reset max_parallel_workers_per_gather;
select jsonb_pretty(explain_analyze_inc_sort_nodes_without_memory('select * from (select * from t order by a) s order by a, b limit 70'));
reset max_parallel_workers_per_gather;
select explain_analyze_inc_sort_nodes_verify_invariants('select * from (select * from t order by a) s order by a, b limit 70');
delete from t;

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