[PATCH] added parallel tid range scan feature
Cary Huang <cary.huang@highgo.ca>
From: Cary Huang <cary.huang@highgo.ca>
To:
Date: 2024-04-29T21:48:44Z
Lists: pgsql-hackers
---
src/backend/access/heap/heapam.c | 19 +++--
src/backend/access/table/tableam.c | 29 +++++++
src/backend/executor/execParallel.c | 20 +++++
src/backend/executor/nodeTidrangescan.c | 81 +++++++++++++++++++
src/backend/optimizer/path/allpaths.c | 5 ++
src/backend/optimizer/path/costsize.c | 22 +++++
src/backend/optimizer/path/tidpath.c | 31 ++++++-
src/backend/optimizer/util/pathnode.c | 7 +-
src/include/access/tableam.h | 12 +++
src/include/executor/nodeTidrangescan.h | 7 ++
src/include/nodes/execnodes.h | 1 +
src/include/optimizer/pathnode.h | 3 +-
src/include/optimizer/paths.h | 2 +
src/test/regress/expected/select_parallel.out | 51 ++++++++++++
src/test/regress/sql/select_parallel.sql | 15 ++++
15 files changed, 293 insertions(+), 12 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 4be0dee4de..2cbb058e96 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -1367,7 +1367,8 @@ heap_set_tidrange(TableScanDesc sscan, ItemPointer mintid,
* Check for an empty range and protect from would be negative results
* from the numBlks calculation below.
*/
- if (ItemPointerCompare(&highestItem, &lowestItem) < 0)
+ if (ItemPointerCompare(&highestItem, &lowestItem) < 0 &&
+ sscan->rs_parallel == NULL)
{
/* Set an empty range of blocks to scan */
heap_setscanlimits(sscan, 0, 0);
@@ -1381,15 +1382,19 @@ heap_set_tidrange(TableScanDesc sscan, ItemPointer mintid,
* lowestItem has an offset above MaxOffsetNumber. In this case, we could
* advance startBlk by one. Likewise, if highestItem has an offset of 0
* we could scan one fewer blocks. However, such an optimization does not
- * seem worth troubling over, currently.
+ * seem worth troubling over, currently. This is set only in non-parallel
+ * case.
*/
- startBlk = ItemPointerGetBlockNumberNoCheck(&lowestItem);
+ if (sscan->rs_parallel == NULL)
+ {
+ startBlk = ItemPointerGetBlockNumberNoCheck(&lowestItem);
- numBlks = ItemPointerGetBlockNumberNoCheck(&highestItem) -
- ItemPointerGetBlockNumberNoCheck(&lowestItem) + 1;
+ numBlks = ItemPointerGetBlockNumberNoCheck(&highestItem) -
+ ItemPointerGetBlockNumberNoCheck(&lowestItem) + 1;
- /* Set the start block and number of blocks to scan */
- heap_setscanlimits(sscan, startBlk, numBlks);
+ /* Set the start block and number of blocks to scan */
+ heap_setscanlimits(sscan, startBlk, numBlks);
+ }
/* Finally, set the TID range in sscan */
ItemPointerCopy(&lowestItem, &sscan->rs_mintid);
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index e57a0b7ea3..38253643e8 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -187,6 +187,35 @@ table_beginscan_parallel(Relation relation, ParallelTableScanDesc pscan)
pscan, flags);
}
+TableScanDesc
+table_beginscan_parallel_tidrange(Relation relation, ParallelTableScanDesc pscan,
+ ItemPointer mintid, ItemPointer maxtid)
+{
+ Snapshot snapshot;
+ uint32 flags = SO_TYPE_TIDRANGESCAN | SO_ALLOW_PAGEMODE;
+ TableScanDesc sscan;
+
+ Assert(RelationGetRelid(relation) == pscan->phs_relid);
+
+ if (!pscan->phs_snapshot_any)
+ {
+ /* Snapshot was serialized -- restore it */
+ snapshot = RestoreSnapshot((char *) pscan + pscan->phs_snapshot_off);
+ RegisterSnapshot(snapshot);
+ flags |= SO_TEMP_SNAPSHOT;
+ }
+ else
+ {
+ /* SnapshotAny passed by caller (not serialized) */
+ snapshot = SnapshotAny;
+ }
+
+ sscan = relation->rd_tableam->scan_begin(relation, snapshot, 0, NULL,
+ pscan, flags);
+
+ return sscan;
+}
+
/* ----------------------------------------------------------------------------
* Index scan related functions.
diff --git a/src/backend/executor/execParallel.c b/src/backend/executor/execParallel.c
index 8c53d1834e..e4733ca5a3 100644
--- a/src/backend/executor/execParallel.c
+++ b/src/backend/executor/execParallel.c
@@ -40,6 +40,7 @@
#include "executor/nodeSort.h"
#include "executor/nodeSubplan.h"
#include "executor/tqueue.h"
+#include "executor/nodeTidrangescan.h"
#include "jit/jit.h"
#include "nodes/nodeFuncs.h"
#include "pgstat.h"
@@ -296,6 +297,11 @@ ExecParallelEstimate(PlanState *planstate, ExecParallelEstimateContext *e)
/* even when not parallel-aware, for EXPLAIN ANALYZE */
ExecMemoizeEstimate((MemoizeState *) planstate, e->pcxt);
break;
+ case T_TidRangeScanState:
+ if (planstate->plan->parallel_aware)
+ ExecTidRangeScanEstimate((TidRangeScanState *) planstate,
+ e->pcxt);
+ break;
default:
break;
}
@@ -520,6 +526,11 @@ ExecParallelInitializeDSM(PlanState *planstate,
/* even when not parallel-aware, for EXPLAIN ANALYZE */
ExecMemoizeInitializeDSM((MemoizeState *) planstate, d->pcxt);
break;
+ case T_TidRangeScanState:
+ if (planstate->plan->parallel_aware)
+ ExecTidRangeScanInitializeDSM((TidRangeScanState *) planstate,
+ d->pcxt);
+ break;
default:
break;
}
@@ -1006,6 +1017,11 @@ ExecParallelReInitializeDSM(PlanState *planstate,
case T_MemoizeState:
/* these nodes have DSM state, but no reinitialization is required */
break;
+ case T_TidRangeScanState:
+ if (planstate->plan->parallel_aware)
+ ExecTidRangeScanReInitializeDSM((TidRangeScanState *) planstate,
+ pcxt);
+ break;
default:
break;
@@ -1372,6 +1388,10 @@ ExecParallelInitializeWorker(PlanState *planstate, ParallelWorkerContext *pwcxt)
/* even when not parallel-aware, for EXPLAIN ANALYZE */
ExecMemoizeInitializeWorker((MemoizeState *) planstate, pwcxt);
break;
+ case T_TidRangeScanState:
+ if (planstate->plan->parallel_aware)
+ ExecTidRangeScanInitializeWorker((TidRangeScanState *) planstate, pwcxt);
+ break;
default:
break;
}
diff --git a/src/backend/executor/nodeTidrangescan.c b/src/backend/executor/nodeTidrangescan.c
index 9aa7683d7e..a353a17731 100644
--- a/src/backend/executor/nodeTidrangescan.c
+++ b/src/backend/executor/nodeTidrangescan.c
@@ -403,3 +403,84 @@ ExecInitTidRangeScan(TidRangeScan *node, EState *estate, int eflags)
*/
return tidrangestate;
}
+/* ----------------------------------------------------------------
+ * Parallel Scan Support
+ * ----------------------------------------------------------------
+ */
+
+/* ----------------------------------------------------------------
+ * ExecTidRangeScanEstimate
+ *
+ * Compute the amount of space we'll need in the parallel
+ * query DSM, and inform pcxt->estimator about our needs.
+ * ----------------------------------------------------------------
+ */
+void
+ExecTidRangeScanEstimate(TidRangeScanState *node,
+ ParallelContext *pcxt)
+{
+ EState *estate = node->ss.ps.state;
+
+ node->pscan_len = table_parallelscan_estimate(node->ss.ss_currentRelation,
+ estate->es_snapshot);
+ shm_toc_estimate_chunk(&pcxt->estimator, node->pscan_len);
+ shm_toc_estimate_keys(&pcxt->estimator, 1);
+}
+
+/* ----------------------------------------------------------------
+ * ExecTidRangeScanInitializeDSM
+ *
+ * Set up a parallel heap scan descriptor.
+ * ----------------------------------------------------------------
+ */
+void
+ExecTidRangeScanInitializeDSM(TidRangeScanState *node,
+ ParallelContext *pcxt)
+{
+ EState *estate = node->ss.ps.state;
+ ParallelTableScanDesc pscan;
+
+ pscan = shm_toc_allocate(pcxt->toc, node->pscan_len);
+ table_parallelscan_initialize(node->ss.ss_currentRelation,
+ pscan,
+ estate->es_snapshot);
+ 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,
+ &node->trss_mintid, &node->trss_maxtid);
+}
+
+/* ----------------------------------------------------------------
+ * ExecTidRangeScanReInitializeDSM
+ *
+ * Reset shared state before beginning a fresh scan.
+ * ----------------------------------------------------------------
+ */
+void
+ExecTidRangeScanReInitializeDSM(TidRangeScanState *node,
+ ParallelContext *pcxt)
+{
+ ParallelTableScanDesc pscan;
+
+ pscan = node->ss.ss_currentScanDesc->rs_parallel;
+ table_parallelscan_reinitialize(node->ss.ss_currentRelation, pscan);
+
+}
+
+/* ----------------------------------------------------------------
+ * ExecSeqScanInitializeWorker
+ *
+ * Copy relevant information from TOC into planstate.
+ * ----------------------------------------------------------------
+ */
+void
+ExecTidRangeScanInitializeWorker(TidRangeScanState *node,
+ ParallelWorkerContext *pwcxt)
+{
+ ParallelTableScanDesc pscan;
+
+ pscan = shm_toc_lookup(pwcxt->toc, node->ss.ps.plan->plan_node_id, false);
+ node->ss.ss_currentScanDesc =
+ table_beginscan_parallel_tidrange(node->ss.ss_currentRelation, pscan,
+ &node->trss_mintid, &node->trss_maxtid);
+}
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index cc51ae1757..ab0d1d5fb7 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -794,6 +794,7 @@ static void
create_plain_partial_paths(PlannerInfo *root, RelOptInfo *rel)
{
int parallel_workers;
+ Path *path = NULL;
parallel_workers = compute_parallel_worker(rel, rel->pages, -1,
max_parallel_workers_per_gather);
@@ -804,6 +805,10 @@ create_plain_partial_paths(PlannerInfo *root, RelOptInfo *rel)
/* Add an unordered partial path based on a parallel sequential scan. */
add_partial_path(rel, create_seqscan_path(root, rel, NULL, parallel_workers));
+
+ path = create_tidrangescan_subpaths(root, rel, parallel_workers);
+ if (path)
+ add_partial_path(rel, path);
}
/*
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index ee23ed7835..262b1ef02d 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -1435,6 +1435,28 @@ cost_tidrangescan(Path *path, PlannerInfo *root,
startup_cost += path->pathtarget->cost.startup;
run_cost += path->pathtarget->cost.per_tuple * path->rows;
+ /* Adjust costing for parallelism, if used. */
+ if (path->parallel_workers > 0)
+ {
+ double parallel_divisor = get_parallel_divisor(path);
+
+ /* The CPU cost is divided among all the workers. */
+ run_cost /= parallel_divisor;
+
+ /*
+ * It may be possible to amortize some of the I/O cost, but probably
+ * not very much, because most operating systems already do aggressive
+ * prefetching. For now, we assume that the disk run cost can't be
+ * amortized at all.
+ */
+
+ /*
+ * In the case of a parallel plan, the row count needs to represent
+ * the number of tuples processed per worker.
+ */
+ path->rows = clamp_row_est(path->rows / parallel_divisor);
+ }
+
path->startup_cost = startup_cost;
path->total_cost = startup_cost + run_cost;
}
diff --git a/src/backend/optimizer/path/tidpath.c b/src/backend/optimizer/path/tidpath.c
index 2ae5ddfe43..c5413be9e6 100644
--- a/src/backend/optimizer/path/tidpath.c
+++ b/src/backend/optimizer/path/tidpath.c
@@ -496,7 +496,8 @@ create_tidscan_paths(PlannerInfo *root, RelOptInfo *rel)
add_path(rel, (Path *) create_tidrangescan_path(root, rel,
tidrangequals,
- required_outer));
+ required_outer,
+ 0));
}
/*
@@ -526,3 +527,31 @@ create_tidscan_paths(PlannerInfo *root, RelOptInfo *rel)
*/
BuildParameterizedTidPaths(root, rel, rel->joininfo);
}
+
+Path *
+create_tidrangescan_subpaths(PlannerInfo *root, RelOptInfo *rel, int parallel_workers)
+{
+ List *tidrangequals;
+ Path *path;
+ /*
+ * If there are range quals in the baserestrict list, generate a
+ * TidRangePath.
+ */
+ tidrangequals = TidRangeQualFromRestrictInfoList(rel->baserestrictinfo,
+ rel);
+
+ if (tidrangequals != NIL)
+ {
+ /*
+ * This path uses no join clauses, but it could still have required
+ * parameterization due to LATERAL refs in its tlist.
+ */
+ Relids required_outer = rel->lateral_relids;
+ path = (Path *) create_tidrangescan_path(root, rel,
+ tidrangequals,
+ required_outer,
+ parallel_workers);
+ return path;
+ }
+ return NULL;
+}
diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index 3cf1dac087..7ceeaf8688 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -1206,7 +1206,8 @@ create_tidscan_path(PlannerInfo *root, RelOptInfo *rel, List *tidquals,
*/
TidRangePath *
create_tidrangescan_path(PlannerInfo *root, RelOptInfo *rel,
- List *tidrangequals, Relids required_outer)
+ List *tidrangequals, Relids required_outer,
+ int parallel_workers)
{
TidRangePath *pathnode = makeNode(TidRangePath);
@@ -1215,9 +1216,9 @@ create_tidrangescan_path(PlannerInfo *root, RelOptInfo *rel,
pathnode->path.pathtarget = rel->reltarget;
pathnode->path.param_info = get_baserel_parampathinfo(root, rel,
required_outer);
- pathnode->path.parallel_aware = false;
+ pathnode->path.parallel_aware = (parallel_workers > 0);
pathnode->path.parallel_safe = rel->consider_parallel;
- pathnode->path.parallel_workers = 0;
+ pathnode->path.parallel_workers = parallel_workers;
pathnode->path.pathkeys = NIL; /* always unordered */
pathnode->tidrangequals = tidrangequals;
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index 8e583b45cd..14c4a694a1 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -1175,6 +1175,18 @@ extern void table_parallelscan_initialize(Relation rel,
extern TableScanDesc table_beginscan_parallel(Relation relation,
ParallelTableScanDesc pscan);
+/*
+ * Begin a parallel tidrange scan. `pscan` needs to have been initialized with
+ * table_parallelscan_initialize(), for the same relation. The initialization
+ * does not need to have happened in this backend.
+ *
+ * Caller must hold a suitable lock on the relation.
+ */
+extern TableScanDesc table_beginscan_parallel_tidrange(Relation relation,
+ ParallelTableScanDesc pscan,
+ ItemPointer mintid,
+ ItemPointer maxtid);
+
/*
* Restart a parallel scan. Call this in the leader process. Caller is
* responsible for making sure that all workers have finished the scan
diff --git a/src/include/executor/nodeTidrangescan.h b/src/include/executor/nodeTidrangescan.h
index 1cfc7a07be..977cb8eb6e 100644
--- a/src/include/executor/nodeTidrangescan.h
+++ b/src/include/executor/nodeTidrangescan.h
@@ -14,6 +14,7 @@
#ifndef NODETIDRANGESCAN_H
#define NODETIDRANGESCAN_H
+#include "access/parallel.h"
#include "nodes/execnodes.h"
extern TidRangeScanState *ExecInitTidRangeScan(TidRangeScan *node,
@@ -21,4 +22,10 @@ extern TidRangeScanState *ExecInitTidRangeScan(TidRangeScan *node,
extern void ExecEndTidRangeScan(TidRangeScanState *node);
extern void ExecReScanTidRangeScan(TidRangeScanState *node);
+/* parallel scan support */
+extern void ExecTidRangeScanEstimate(TidRangeScanState *node, ParallelContext *pcxt);
+extern void ExecTidRangeScanInitializeDSM(TidRangeScanState *node, ParallelContext *pcxt);
+extern void ExecTidRangeScanReInitializeDSM(TidRangeScanState *node, ParallelContext *pcxt);
+extern void ExecTidRangeScanInitializeWorker(TidRangeScanState *node, ParallelWorkerContext *pwcxt);
+
#endif /* NODETIDRANGESCAN_H */
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index d927ac44a8..81eec34730 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1862,6 +1862,7 @@ typedef struct TidRangeScanState
ItemPointerData trss_mintid;
ItemPointerData trss_maxtid;
bool trss_inScan;
+ Size pscan_len; /* size of parallel tid range scan descriptor */
} TidRangeScanState;
/* ----------------
diff --git a/src/include/optimizer/pathnode.h b/src/include/optimizer/pathnode.h
index c5c4756b0f..d7683ec1c3 100644
--- a/src/include/optimizer/pathnode.h
+++ b/src/include/optimizer/pathnode.h
@@ -66,7 +66,8 @@ extern TidPath *create_tidscan_path(PlannerInfo *root, RelOptInfo *rel,
extern TidRangePath *create_tidrangescan_path(PlannerInfo *root,
RelOptInfo *rel,
List *tidrangequals,
- Relids required_outer);
+ Relids required_outer,
+ int parallel_workers);
extern AppendPath *create_append_path(PlannerInfo *root, RelOptInfo *rel,
List *subpaths, List *partial_subpaths,
List *pathkeys, Relids required_outer,
diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index 39ba461548..c571354890 100644
--- a/src/include/optimizer/paths.h
+++ b/src/include/optimizer/paths.h
@@ -87,6 +87,8 @@ extern void check_index_predicates(PlannerInfo *root, RelOptInfo *rel);
* routines to generate tid paths
*/
extern void create_tidscan_paths(PlannerInfo *root, RelOptInfo *rel);
+extern Path *create_tidrangescan_subpaths(PlannerInfo *root, RelOptInfo *rel,
+ int parallel_worker);
/*
* joinpath.c
diff --git a/src/test/regress/expected/select_parallel.out b/src/test/regress/expected/select_parallel.out
index 87273fa635..61e6700194 100644
--- a/src/test/regress/expected/select_parallel.out
+++ b/src/test/regress/expected/select_parallel.out
@@ -1293,4 +1293,55 @@ SELECT 1 FROM tenk1_vw_sec
Filter: (f1 < tenk1_vw_sec.unique1)
(9 rows)
+-- test parallel tid range scan
+EXPLAIN (COSTS OFF)
+SELECT ctid FROM tenk1 WHERE ctid > '(0,1)' LIMIT 1;
+ QUERY PLAN
+-----------------------------------------------
+ Limit
+ -> Gather
+ Workers Planned: 4
+ -> Parallel Tid Range Scan on tenk1
+ TID Cond: (ctid > '(0,1)'::tid)
+(5 rows)
+
+EXPLAIN (COSTS OFF)
+SELECT ctid FROM tenk1 WHERE ctid < '(400,1)' LIMIT 1;
+ QUERY PLAN
+-------------------------------------------------
+ Limit
+ -> Gather
+ Workers Planned: 4
+ -> Parallel Tid Range Scan on tenk1
+ TID Cond: (ctid < '(400,1)'::tid)
+(5 rows)
+
+EXPLAIN (COSTS OFF)
+SELECT ctid FROM tenk1 WHERE ctid >= '(0,1)' AND ctid <= '(400,1)' LIMIT 1;
+ QUERY PLAN
+-------------------------------------------------------------------------------
+ Limit
+ -> Gather
+ Workers Planned: 4
+ -> Parallel Tid Range Scan on tenk1
+ TID Cond: ((ctid >= '(0,1)'::tid) AND (ctid <= '(400,1)'::tid))
+(5 rows)
+
+EXPLAIN (COSTS OFF)
+SELECT t.ctid,t2.c FROM tenk1 t,
+LATERAL (SELECT count(*) c FROM tenk1 t2 WHERE t2.ctid <= t.ctid) t2
+WHERE t.ctid < '(1,0)' LIMIT 1;
+ QUERY PLAN
+------------------------------------------------------
+ Limit
+ -> Nested Loop
+ -> Gather
+ Workers Planned: 4
+ -> Parallel Tid Range Scan on tenk1 t
+ TID Cond: (ctid < '(1,0)'::tid)
+ -> Aggregate
+ -> Tid Range Scan on tenk1 t2
+ TID Cond: (ctid <= t.ctid)
+(9 rows)
+
rollback;
diff --git a/src/test/regress/sql/select_parallel.sql b/src/test/regress/sql/select_parallel.sql
index 20376c03fa..1d4ef68790 100644
--- a/src/test/regress/sql/select_parallel.sql
+++ b/src/test/regress/sql/select_parallel.sql
@@ -495,4 +495,19 @@ EXPLAIN (COSTS OFF)
SELECT 1 FROM tenk1_vw_sec
WHERE (SELECT sum(f1) FROM int4_tbl WHERE f1 < unique1) < 100;
+-- test parallel tid range scan
+EXPLAIN (COSTS OFF)
+SELECT ctid FROM tenk1 WHERE ctid > '(0,1)' LIMIT 1;
+
+EXPLAIN (COSTS OFF)
+SELECT ctid FROM tenk1 WHERE ctid < '(400,1)' LIMIT 1;
+
+EXPLAIN (COSTS OFF)
+SELECT ctid FROM tenk1 WHERE ctid >= '(0,1)' AND ctid <= '(400,1)' LIMIT 1;
+
+EXPLAIN (COSTS OFF)
+SELECT t.ctid,t2.c FROM tenk1 t,
+LATERAL (SELECT count(*) c FROM tenk1 t2 WHERE t2.ctid <= t.ctid) t2
+WHERE t.ctid < '(1,0)' LIMIT 1;
+
rollback;
--
2.17.1
------=_Part_16932350_1227316839.1714430159396--