v8-0002-fixup-v7-parallel-TID-range-scan-patch.patch

From 4d829073090d882bd7d61a1b1ffcb2fea280515a Mon Sep 17 00:00:00 2001
From: David Rowley <dgrowley@gmail.com>
Date: Mon, 28 Jul 2025 17:58:58 +1200
Subject: [PATCH v8 2/2] fixup! v7 parallel TID range scan patch

---
 src/backend/access/heap/heapam.c           | 28 ++++++++++----------
 src/backend/access/table/tableam.c         | 16 +++++-------
 src/backend/executor/execParallel.c        |  1 +
 src/backend/executor/nodeTidrangescan.c    | 13 ++++------
 src/backend/optimizer/path/costsize.c      | 14 +++++-----
 src/backend/optimizer/path/tidpath.c       | 10 +++++---
 src/include/nodes/execnodes.h              |  2 +-
 src/test/regress/expected/tidrangescan.out | 30 +++++++++++-----------
 src/test/regress/sql/tidrangescan.sql      | 30 +++++++++++-----------
 9 files changed, 71 insertions(+), 73 deletions(-)

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 5105a2c8ad3..d0e650de573 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -490,6 +490,21 @@ heap_setscanlimits(TableScanDesc sscan, BlockNumber startBlk, BlockNumber numBlk
 
 	scan->rs_startblock = startBlk;
 	scan->rs_numblocks = numBlks;
+
+	/* set the limits in the ParallelBlockTableScanDesc, when present */
+
+	/*
+	 * XXX no lock is being taken here.  What guarantees are there that there
+	 * isn't some worker using the old limits when the new limits are imposed?
+	 */
+	if (scan->rs_base.rs_parallel != NULL)
+	{
+		ParallelBlockTableScanDesc bpscan;
+
+		bpscan = (ParallelBlockTableScanDesc) scan->rs_base.rs_parallel;
+		bpscan->phs_startblock = startBlk;
+		bpscan->phs_numblock = numBlks;
+	}
 }
 
 /*
@@ -1478,19 +1493,6 @@ heap_set_tidrange(TableScanDesc sscan, ItemPointer mintid,
 	/* Set the start block and number of blocks to scan */
 	heap_setscanlimits(sscan, startBlk, numBlks);
 
-	/*
-	 * If parallel mode is used, store startBlk and numBlks in parallel
-	 * scan descriptor as well.
-	 */
-	if (scan->rs_base.rs_parallel != NULL)
-	{
-		ParallelBlockTableScanDesc bpscan = NULL;
-
-		bpscan = (ParallelBlockTableScanDesc) scan->rs_base.rs_parallel;
-		bpscan->phs_startblock = startBlk;
-		bpscan->phs_numblock = numBlks;
-	}
-
 	/* Finally, set the TID range in sscan */
 	ItemPointerCopy(&lowestItem, &sscan->st.tidrange.rs_mintid);
 	ItemPointerCopy(&highestItem, &sscan->st.tidrange.rs_maxtid);
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 5a76cec81e9..8036654c773 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -197,6 +197,9 @@ table_beginscan_parallel_tidrange(Relation relation, ParallelTableScanDesc pscan
 
 	Assert(RelFileLocatorEquals(relation->rd_locator, pscan->phs_locator));
 
+	/* disable syncscan in parallel tid range scan. */
+	pscan->phs_syncscan = false;
+
 	if (!pscan->phs_snapshot_any)
 	{
 		/* Snapshot was serialized -- restore it */
@@ -607,18 +610,11 @@ table_block_parallelscan_nextpage(Relation rel,
 	}
 
 	/*
-	 * In a parallel TID range scan, 'pbscan->phs_numblock' is non-zero if an
-	 * upper TID range limit is specified, or InvalidBlockNumber if no limit
-	 * is given. This value may be less than or equal to 'pbscan->phs_nblocks'
-	 * , which is the total number of blocks in the relation.
-	 *
-	 * The scan can terminate early once 'nallocated' reaches
-	 * 'pbscan->phs_numblock', even if the full relation has remaining blocks
-	 * to scan. This ensures that parallel workers only scan the subset of
-	 * blocks that fall within the TID range.
+	 * Check if we've allocated every block in the relation, or if we've
+	 * reached the limit imposed by pbscan->phs_numblock (if set).
 	 */
 	if (nallocated >= pbscan->phs_nblocks)
-	    page = InvalidBlockNumber; /* all blocks have been allocated */
+		page = InvalidBlockNumber; /* all blocks have been allocated */
 	else if (pbscan->phs_numblock != InvalidBlockNumber &&
 			 nallocated >= pbscan->phs_numblock)
 		page = InvalidBlockNumber; /* upper scan limit reached */
diff --git a/src/backend/executor/execParallel.c b/src/backend/executor/execParallel.c
index 3255d92cffd..3f0dc5322ce 100644
--- a/src/backend/executor/execParallel.c
+++ b/src/backend/executor/execParallel.c
@@ -1036,6 +1036,7 @@ ExecParallelReInitializeDSM(PlanState *planstate,
 		case T_MemoizeState:
 			/* these nodes have DSM state, but no reinitialization is required */
 			break;
+
 		default:
 			break;
 	}
diff --git a/src/backend/executor/nodeTidrangescan.c b/src/backend/executor/nodeTidrangescan.c
index 06a1037d51e..afa47b01dec 100644
--- a/src/backend/executor/nodeTidrangescan.c
+++ b/src/backend/executor/nodeTidrangescan.c
@@ -418,13 +418,13 @@ ExecInitTidRangeScan(TidRangeScan *node, EState *estate, int eflags)
  * ----------------------------------------------------------------
  */
 void
-ExecTidRangeScanEstimate(TidRangeScanState *node,
-					ParallelContext *pcxt)
+ExecTidRangeScanEstimate(TidRangeScanState *node, ParallelContext *pcxt)
 {
 	EState	   *estate = node->ss.ps.state;
 
-	node->trss_pscanlen = table_parallelscan_estimate(node->ss.ss_currentRelation,
-												  estate->es_snapshot);
+	node->trss_pscanlen =
+		table_parallelscan_estimate(node->ss.ss_currentRelation,
+									estate->es_snapshot);
 	shm_toc_estimate_chunk(&pcxt->estimator, node->trss_pscanlen);
 	shm_toc_estimate_keys(&pcxt->estimator, 1);
 }
@@ -436,8 +436,7 @@ ExecTidRangeScanEstimate(TidRangeScanState *node,
  * ----------------------------------------------------------------
  */
 void
-ExecTidRangeScanInitializeDSM(TidRangeScanState *node,
-						 ParallelContext *pcxt)
+ExecTidRangeScanInitializeDSM(TidRangeScanState *node, ParallelContext *pcxt)
 {
 	EState	   *estate = node->ss.ps.state;
 	ParallelTableScanDesc pscan;
@@ -446,8 +445,6 @@ ExecTidRangeScanInitializeDSM(TidRangeScanState *node,
 	table_parallelscan_initialize(node->ss.ss_currentRelation,
 								  pscan,
 								  estate->es_snapshot);
-	/* disable syncscan in parallel tid range scan. */
-	pscan->phs_syncscan = false;
 	shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id, pscan);
 	node->ss.ss_currentScanDesc =
 		table_beginscan_parallel_tidrange(node->ss.ss_currentRelation, pscan);
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index fdb58d094f2..eab1b18d30e 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -1366,9 +1366,9 @@ cost_tidrangescan(Path *path, PlannerInfo *root,
 {
 	Selectivity selectivity;
 	double		pages;
-	Cost		startup_cost = 0;
-	Cost		cpu_run_cost = 0;
-	Cost		disk_run_cost = 0;
+	Cost		startup_cost;
+	Cost		cpu_run_cost;
+	Cost		disk_run_cost;
 	QualCost	qpqual_cost;
 	Cost		cpu_per_tuple;
 	QualCost	tid_qual_cost;
@@ -1414,7 +1414,7 @@ cost_tidrangescan(Path *path, PlannerInfo *root,
 							  &spc_seq_page_cost);
 
 	/* disk costs; 1 random page and the remainder as seq pages */
-	disk_run_cost += spc_random_page_cost + spc_seq_page_cost * nseqpages;
+	disk_run_cost = spc_random_page_cost + spc_seq_page_cost * nseqpages;
 
 	/* Add scanning CPU costs */
 	get_restriction_qual_cost(root, baserel, param_info, &qpqual_cost);
@@ -1422,14 +1422,14 @@ cost_tidrangescan(Path *path, PlannerInfo *root,
 	/*
 	 * XXX currently we assume TID quals are a subset of qpquals at this
 	 * point; they will be removed (if possible) when we create the plan, so
-	 * we subtract their cost from the total qpqual cost. (If the TID quals
+	 * we subtract their cost from the total qpqual cost.  (If the TID quals
 	 * can't be removed, this is a mistake and we're going to underestimate
 	 * the CPU cost a bit.)
 	 */
-	startup_cost += qpqual_cost.startup + tid_qual_cost.per_tuple;
+	startup_cost = qpqual_cost.startup + tid_qual_cost.per_tuple;
 	cpu_per_tuple = cpu_tuple_cost + qpqual_cost.per_tuple -
 		tid_qual_cost.per_tuple;
-	cpu_run_cost += cpu_per_tuple * ntuples;
+	cpu_run_cost = cpu_per_tuple * ntuples;
 
 	/* tlist eval costs are paid per output row, not per tuple scanned */
 	startup_cost += path->pathtarget->cost.startup;
diff --git a/src/backend/optimizer/path/tidpath.c b/src/backend/optimizer/path/tidpath.c
index 9c78eedcf51..e48c85833e7 100644
--- a/src/backend/optimizer/path/tidpath.c
+++ b/src/backend/optimizer/path/tidpath.c
@@ -564,11 +564,13 @@ create_tidscan_paths(PlannerInfo *root, RelOptInfo *rel)
 
 			parallel_workers = compute_parallel_worker(rel, rel->pages, -1,
 													   max_parallel_workers_per_gather);
+
 			if (parallel_workers > 0)
-			{
-				add_partial_path(rel, (Path *) create_tidrangescan_path(root, rel, tidrangequals,
-								required_outer, parallel_workers));
-			}
+				add_partial_path(rel, (Path *) create_tidrangescan_path(root,
+																		rel,
+																		tidrangequals,
+																		required_outer,
+																		parallel_workers));
 		}
 	}
 
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 958c78f66c9..4947b6cca00 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1929,7 +1929,7 @@ typedef struct TidScanState
  *		trss_mintid			the lowest TID in the scan range
  *		trss_maxtid			the highest TID in the scan range
  *		trss_inScan			is a scan currently in progress?
- *		trss_pscanlen		size of parallel TID range scan descriptor
+ *		trss_pscanlen		size of parallel heap scan descriptor
  * ----------------
  */
 typedef struct TidRangeScanState
diff --git a/src/test/regress/expected/tidrangescan.out b/src/test/regress/expected/tidrangescan.out
index 32cd2bd9f49..3c5fc9e102a 100644
--- a/src/test/regress/expected/tidrangescan.out
+++ b/src/test/regress/expected/tidrangescan.out
@@ -298,13 +298,13 @@ FETCH LAST c;
 COMMIT;
 DROP TABLE tidrangescan;
 -- tests for parallel tidrangescans
-SET parallel_setup_cost=0;
-SET parallel_tuple_cost=0;
-SET min_parallel_table_scan_size=0;
-SET max_parallel_workers_per_gather=4;
-CREATE TABLE parallel_tidrangescan(id integer, data text) WITH (fillfactor=10);
+SET parallel_setup_cost TO 0;
+SET parallel_tuple_cost TO 0;
+SET min_parallel_table_scan_size TO 0;
+SET max_parallel_workers_per_gather TO 4;
+CREATE TABLE parallel_tidrangescan(id integer, data text) WITH (fillfactor = 10);
 -- insert enough tuples such that each page gets 5 tuples with fillfactor = 10
-INSERT INTO parallel_tidrangescan SELECT i,repeat('x', 100) FROM generate_series(1,200) AS s(i);
+INSERT INTO parallel_tidrangescan SELECT i, repeat('x', 100) FROM generate_series(1,200) AS s(i);
 -- ensure there are 40 pages for parallel test
 SELECT min(ctid), max(ctid) FROM parallel_tidrangescan;
   min  |  max   
@@ -313,8 +313,8 @@ SELECT min(ctid), max(ctid) FROM parallel_tidrangescan;
 (1 row)
 
 -- parallel range scans with upper bound
-EXPLAIN (costs off)
-SELECT count(*) FROM parallel_tidrangescan WHERE ctid<'(30,1)';
+EXPLAIN (COSTS OFF)
+SELECT count(*) FROM parallel_tidrangescan WHERE ctid < '(30,1)';
                              QUERY PLAN                             
 --------------------------------------------------------------------
  Finalize Aggregate
@@ -325,15 +325,15 @@ SELECT count(*) FROM parallel_tidrangescan WHERE ctid<'(30,1)';
                      TID Cond: (ctid < '(30,1)'::tid)
 (6 rows)
 
-SELECT count(*) FROM parallel_tidrangescan WHERE ctid<'(30,1)';
+SELECT count(*) FROM parallel_tidrangescan WHERE ctid < '(30,1)';
  count 
 -------
    150
 (1 row)
 
 -- parallel range scans with lower bound
-EXPLAIN (costs off)
-SELECT count(*) FROM parallel_tidrangescan WHERE ctid>'(10,0)';
+EXPLAIN (COSTS OFF)
+SELECT count(*) FROM parallel_tidrangescan WHERE ctid > '(10,0)';
                              QUERY PLAN                             
 --------------------------------------------------------------------
  Finalize Aggregate
@@ -344,15 +344,15 @@ SELECT count(*) FROM parallel_tidrangescan WHERE ctid>'(10,0)';
                      TID Cond: (ctid > '(10,0)'::tid)
 (6 rows)
 
-SELECT count(*) FROM parallel_tidrangescan WHERE ctid>'(10,0)';
+SELECT count(*) FROM parallel_tidrangescan WHERE ctid > '(10,0)';
  count 
 -------
    150
 (1 row)
 
 -- parallel range scans with both bounds
-EXPLAIN (costs off)
-SELECT count(*) FROM parallel_tidrangescan WHERE ctid>'(10,0)' AND ctid<'(30,1)';
+EXPLAIN (COSTS OFF)
+SELECT count(*) FROM parallel_tidrangescan WHERE ctid > '(10,0)' AND ctid < '(30,1)';
                                     QUERY PLAN                                     
 -----------------------------------------------------------------------------------
  Finalize Aggregate
@@ -363,7 +363,7 @@ SELECT count(*) FROM parallel_tidrangescan WHERE ctid>'(10,0)' AND ctid<'(30,1)'
                      TID Cond: ((ctid > '(10,0)'::tid) AND (ctid < '(30,1)'::tid))
 (6 rows)
 
-SELECT count(*) FROM parallel_tidrangescan WHERE ctid>'(10,0)' AND ctid<'(30,1)';
+SELECT count(*) FROM parallel_tidrangescan WHERE ctid > '(10,0)' AND ctid < '(30,1)';
  count 
 -------
    100
diff --git a/src/test/regress/sql/tidrangescan.sql b/src/test/regress/sql/tidrangescan.sql
index 1d18b8a61dc..0f1e43c6d05 100644
--- a/src/test/regress/sql/tidrangescan.sql
+++ b/src/test/regress/sql/tidrangescan.sql
@@ -99,33 +99,33 @@ COMMIT;
 DROP TABLE tidrangescan;
 
 -- tests for parallel tidrangescans
-SET parallel_setup_cost=0;
-SET parallel_tuple_cost=0;
-SET min_parallel_table_scan_size=0;
-SET max_parallel_workers_per_gather=4;
+SET parallel_setup_cost TO 0;
+SET parallel_tuple_cost TO 0;
+SET min_parallel_table_scan_size TO 0;
+SET max_parallel_workers_per_gather TO 4;
 
-CREATE TABLE parallel_tidrangescan(id integer, data text) WITH (fillfactor=10);
+CREATE TABLE parallel_tidrangescan(id integer, data text) WITH (fillfactor = 10);
 
 -- insert enough tuples such that each page gets 5 tuples with fillfactor = 10
-INSERT INTO parallel_tidrangescan SELECT i,repeat('x', 100) FROM generate_series(1,200) AS s(i);
+INSERT INTO parallel_tidrangescan SELECT i, repeat('x', 100) FROM generate_series(1,200) AS s(i);
 
 -- ensure there are 40 pages for parallel test
 SELECT min(ctid), max(ctid) FROM parallel_tidrangescan;
 
 -- parallel range scans with upper bound
-EXPLAIN (costs off)
-SELECT count(*) FROM parallel_tidrangescan WHERE ctid<'(30,1)';
-SELECT count(*) FROM parallel_tidrangescan WHERE ctid<'(30,1)';
+EXPLAIN (COSTS OFF)
+SELECT count(*) FROM parallel_tidrangescan WHERE ctid < '(30,1)';
+SELECT count(*) FROM parallel_tidrangescan WHERE ctid < '(30,1)';
 
 -- parallel range scans with lower bound
-EXPLAIN (costs off)
-SELECT count(*) FROM parallel_tidrangescan WHERE ctid>'(10,0)';
-SELECT count(*) FROM parallel_tidrangescan WHERE ctid>'(10,0)';
+EXPLAIN (COSTS OFF)
+SELECT count(*) FROM parallel_tidrangescan WHERE ctid > '(10,0)';
+SELECT count(*) FROM parallel_tidrangescan WHERE ctid > '(10,0)';
 
 -- parallel range scans with both bounds
-EXPLAIN (costs off)
-SELECT count(*) FROM parallel_tidrangescan WHERE ctid>'(10,0)' AND ctid<'(30,1)';
-SELECT count(*) FROM parallel_tidrangescan WHERE ctid>'(10,0)' AND ctid<'(30,1)';
+EXPLAIN (COSTS OFF)
+SELECT count(*) FROM parallel_tidrangescan WHERE ctid > '(10,0)' AND ctid < '(30,1)';
+SELECT count(*) FROM parallel_tidrangescan WHERE ctid > '(10,0)' AND ctid < '(30,1)';
 
 -- parallel rescans
 EXPLAIN (COSTS OFF)
-- 
2.43.0