From 9b3ebaad986bf51764487103e977be33d25fb818 Mon Sep 17 00:00:00 2001 From: Saikiran Avula Date: Mon, 6 May 2024 22:29:30 +0100 Subject: [PATCH v1] Skip adding row marks for not target relations when the result relation is a foreign table using early locking. If a result relation is a foreign relation, FDWs have 2 ways for locking - early locking (using select for update) and late locking (using RefetchForeignRow). If FDW uses early locking, then there is no reason for planner to add row marks and project that column duing execution. Currently we fetch whole row var which is not used. This change ensures we do add any row mark for non target relations. --- .../postgres_fdw/expected/postgres_fdw.out | 54 ++++++------- src/backend/optimizer/plan/planner.c | 76 ++++++++++++++----- 2 files changed, 86 insertions(+), 44 deletions(-) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 078b8a966f..d1d6016491 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -6210,25 +6210,25 @@ UPDATE ft2 AS target SET (c2) = ( EXPLAIN (VERBOSE, COSTS OFF) UPDATE ft2 d SET c2 = CASE WHEN random() >= 0 THEN d.c2 ELSE 0 END FROM ft2 AS t WHERE d.c1 = t.c1 AND d.c1 > 1000; - QUERY PLAN ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ + QUERY PLAN +----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Update on public.ft2 d Remote SQL: UPDATE "S 1"."T 1" SET c2 = $2 WHERE ctid = $1 -> Foreign Scan - Output: CASE WHEN (random() >= '0'::double precision) THEN d.c2 ELSE 0 END, d.ctid, d.*, t.* + Output: CASE WHEN (random() >= '0'::double precision) THEN d.c2 ELSE 0 END, d.ctid, d.* Relations: (public.ft2 d) INNER JOIN (public.ft2 t) - Remote SQL: SELECT r1.c2, r1.ctid, CASE WHEN (r1.*)::text IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, CASE WHEN (r2.*)::text IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1."C 1" = r2."C 1")) AND ((r1."C 1" > 1000)))) FOR UPDATE OF r1 + Remote SQL: SELECT r1.c2, r1.ctid, CASE WHEN (r1.*)::text IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1."C 1" = r2."C 1")) AND ((r1."C 1" > 1000)))) FOR UPDATE OF r1 -> Hash Join - Output: d.c2, d.ctid, d.*, t.* + Output: d.c2, d.ctid, d.* Hash Cond: (d.c1 = t.c1) -> Foreign Scan on public.ft2 d Output: d.c2, d.ctid, d.*, d.c1 Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8, ctid FROM "S 1"."T 1" WHERE (("C 1" > 1000)) ORDER BY "C 1" ASC NULLS LAST FOR UPDATE -> Hash - Output: t.*, t.c1 + Output: t.c1 -> Foreign Scan on public.ft2 t - Output: t.*, t.c1 - Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" + Output: t.c1 + Remote SQL: SELECT "C 1" FROM "S 1"."T 1" (17 rows) UPDATE ft2 d SET c2 = CASE WHEN random() >= 0 THEN d.c2 ELSE 0 END @@ -6271,31 +6271,31 @@ UPDATE ft2 SET c3 = 'baz' FROM ft4 INNER JOIN ft5 ON (ft4.c1 = ft5.c1) WHERE ft2.c1 > 2000 AND ft2.c2 === ft4.c1 RETURNING ft2.*, ft4.*, ft5.*; -- can't be pushed down - QUERY PLAN ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- + QUERY PLAN +-------------------------------------------------------------------------------------------------------------------------------------------------- Update on public.ft2 Output: ft2.c1, ft2.c2, ft2.c3, ft2.c4, ft2.c5, ft2.c6, ft2.c7, ft2.c8, ft4.c1, ft4.c2, ft4.c3, ft5.c1, ft5.c2, ft5.c3 Remote SQL: UPDATE "S 1"."T 1" SET c3 = $2 WHERE ctid = $1 RETURNING "C 1", c2, c3, c4, c5, c6, c7, c8 -> Nested Loop - Output: 'baz'::text, ft2.ctid, ft2.*, ft4.*, ft5.*, ft4.c1, ft4.c2, ft4.c3, ft5.c1, ft5.c2, ft5.c3 + Output: 'baz'::text, ft2.ctid, ft2.*, ft4.c1, ft4.c2, ft4.c3, ft5.c1, ft5.c2, ft5.c3 Join Filter: (ft2.c2 === ft4.c1) -> Foreign Scan on public.ft2 Output: ft2.ctid, ft2.*, ft2.c2 Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8, ctid FROM "S 1"."T 1" WHERE (("C 1" > 2000)) FOR UPDATE -> Foreign Scan - Output: ft4.*, ft4.c1, ft4.c2, ft4.c3, ft5.*, ft5.c1, ft5.c2, ft5.c3 + Output: ft4.c1, ft4.c2, ft4.c3, ft5.c1, ft5.c2, ft5.c3 Relations: (public.ft4) INNER JOIN (public.ft5) - Remote SQL: SELECT CASE WHEN (r2.*)::text IS NOT NULL THEN ROW(r2.c1, r2.c2, r2.c3) END, r2.c1, r2.c2, r2.c3, CASE WHEN (r3.*)::text IS NOT NULL THEN ROW(r3.c1, r3.c2, r3.c3) END, r3.c1, r3.c2, r3.c3 FROM ("S 1"."T 3" r2 INNER JOIN "S 1"."T 4" r3 ON (((r2.c1 = r3.c1)))) + Remote SQL: SELECT r2.c1, r2.c2, r2.c3, r3.c1, r3.c2, r3.c3 FROM ("S 1"."T 3" r2 INNER JOIN "S 1"."T 4" r3 ON (((r2.c1 = r3.c1)))) -> Hash Join - Output: ft4.*, ft4.c1, ft4.c2, ft4.c3, ft5.*, ft5.c1, ft5.c2, ft5.c3 + Output: ft4.c1, ft4.c2, ft4.c3, ft5.c1, ft5.c2, ft5.c3 Hash Cond: (ft4.c1 = ft5.c1) -> Foreign Scan on public.ft4 - Output: ft4.*, ft4.c1, ft4.c2, ft4.c3 + Output: ft4.c1, ft4.c2, ft4.c3 Remote SQL: SELECT c1, c2, c3 FROM "S 1"."T 3" -> Hash - Output: ft5.*, ft5.c1, ft5.c2, ft5.c3 + Output: ft5.c1, ft5.c2, ft5.c3 -> Foreign Scan on public.ft5 - Output: ft5.*, ft5.c1, ft5.c2, ft5.c3 + Output: ft5.c1, ft5.c2, ft5.c3 Remote SQL: SELECT c1, c2, c3 FROM "S 1"."T 4" (24 rows) @@ -6313,30 +6313,30 @@ DELETE FROM ft2 USING ft4 INNER JOIN ft5 ON (ft4.c1 === ft5.c1) WHERE ft2.c1 > 2000 AND ft2.c2 = ft4.c1 RETURNING ft2.c1, ft2.c2, ft2.c3; -- can't be pushed down - QUERY PLAN ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- + QUERY PLAN +-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Delete on public.ft2 Output: ft2.c1, ft2.c2, ft2.c3 Remote SQL: DELETE FROM "S 1"."T 1" WHERE ctid = $1 RETURNING "C 1", c2, c3 -> Foreign Scan - Output: ft2.ctid, ft4.*, ft5.* + Output: ft2.ctid Filter: (ft4.c1 === ft5.c1) Relations: ((public.ft2) INNER JOIN (public.ft4)) INNER JOIN (public.ft5) - Remote SQL: SELECT r1.ctid, CASE WHEN (r2.*)::text IS NOT NULL THEN ROW(r2.c1, r2.c2, r2.c3) END, CASE WHEN (r3.*)::text IS NOT NULL THEN ROW(r3.c1, r3.c2, r3.c3) END, r2.c1, r3.c1 FROM (("S 1"."T 1" r1 INNER JOIN "S 1"."T 3" r2 ON (((r1.c2 = r2.c1)) AND ((r1."C 1" > 2000)))) INNER JOIN "S 1"."T 4" r3 ON (TRUE)) FOR UPDATE OF r1 + Remote SQL: SELECT r1.ctid, r2.c1, r3.c1 FROM (("S 1"."T 1" r1 INNER JOIN "S 1"."T 3" r2 ON (((r1.c2 = r2.c1)) AND ((r1."C 1" > 2000)))) INNER JOIN "S 1"."T 4" r3 ON (TRUE)) FOR UPDATE OF r1 -> Nested Loop - Output: ft2.ctid, ft4.*, ft5.*, ft4.c1, ft5.c1 + Output: ft2.ctid, ft4.c1, ft5.c1 -> Nested Loop - Output: ft2.ctid, ft4.*, ft4.c1 + Output: ft2.ctid, ft4.c1 Join Filter: (ft2.c2 = ft4.c1) -> Foreign Scan on public.ft2 Output: ft2.ctid, ft2.c2 Remote SQL: SELECT c2, ctid FROM "S 1"."T 1" WHERE (("C 1" > 2000)) FOR UPDATE -> Foreign Scan on public.ft4 - Output: ft4.*, ft4.c1 - Remote SQL: SELECT c1, c2, c3 FROM "S 1"."T 3" + Output: ft4.c1, ft4.c2, ft4.c3 + Remote SQL: SELECT c1 FROM "S 1"."T 3" -> Foreign Scan on public.ft5 - Output: ft5.*, ft5.c1 - Remote SQL: SELECT c1, c2, c3 FROM "S 1"."T 4" + Output: ft5.c1, ft5.c2, ft5.c3 + Remote SQL: SELECT c1 FROM "S 1"."T 4" (22 rows) DELETE FROM ft2 diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c index 5320da51a0..c4a190fa6c 100644 --- a/src/backend/optimizer/plan/planner.c +++ b/src/backend/optimizer/plan/planner.c @@ -22,6 +22,7 @@ #include "access/parallel.h" #include "access/sysattr.h" #include "access/table.h" +#include "access/relation.h" #include "catalog/pg_aggregate.h" #include "catalog/pg_constraint.h" #include "catalog/pg_inherits.h" @@ -255,6 +256,7 @@ static bool group_by_has_partkey(RelOptInfo *input_rel, static int common_prefix_cmp(const void *a, const void *b); static List *generate_setop_child_grouplist(SetOperationStmt *op, List *targetlist); +static bool relationUsesEarlyLocking(RangeTblEntry *rte); /***************************************************************************** @@ -2269,6 +2271,7 @@ preprocess_rowmarks(PlannerInfo *root) List *prowmarks; ListCell *l; int i; + RangeTblEntry *resultRte = NULL; if (parse->rowMarks) { @@ -2343,28 +2346,39 @@ preprocess_rowmarks(PlannerInfo *root) } /* - * Now, add rowmarks for any non-target, non-locked base relations. + * Check if the result relation uses early locking. In which case we do not + * need to add rowmarks for non target relations. */ - i = 0; - foreach(l, parse->rtable) + if (parse->resultRelation > 0) + resultRte = rt_fetch(parse->resultRelation, parse->rtable); + + if (!relationUsesEarlyLocking(resultRte)) { - RangeTblEntry *rte = lfirst_node(RangeTblEntry, l); - PlanRowMark *newrc; - i++; - if (!bms_is_member(i, rels)) - continue; + /* + * Now, add rowmarks for any non-target, non-locked base relations. + */ + i = 0; + foreach(l, parse->rtable) + { + RangeTblEntry *rte = lfirst_node(RangeTblEntry, l); + PlanRowMark *newrc; - newrc = makeNode(PlanRowMark); - newrc->rti = newrc->prti = i; - newrc->rowmarkId = ++(root->glob->lastRowMarkId); - newrc->markType = select_rowmark_type(rte, LCS_NONE); - newrc->allMarkTypes = (1 << newrc->markType); - newrc->strength = LCS_NONE; - newrc->waitPolicy = LockWaitBlock; /* doesn't matter */ - newrc->isParent = false; + i++; + if (!bms_is_member(i, rels)) + continue; - prowmarks = lappend(prowmarks, newrc); + newrc = makeNode(PlanRowMark); + newrc->rti = newrc->prti = i; + newrc->rowmarkId = ++(root->glob->lastRowMarkId); + newrc->markType = select_rowmark_type(rte, LCS_NONE); + newrc->allMarkTypes = (1 << newrc->markType); + newrc->strength = LCS_NONE; + newrc->waitPolicy = LockWaitBlock; /* doesn't matter */ + newrc->isParent = false; + + prowmarks = lappend(prowmarks, newrc); + } } root->rowMarks = prowmarks; @@ -2422,6 +2436,34 @@ select_rowmark_type(RangeTblEntry *rte, LockClauseStrength strength) } } +/* + * relationUsesEarlyLocking - checks if the relation uses early locking. + * + * We do early locking for a foreign relation if the RefetchForeignRow API is not implemented by FDW. + */ +static bool +relationUsesEarlyLocking(RangeTblEntry *rte) +{ + Relation rel; + FdwRoutine *fdwroutine = NULL; + + /* Early locking is applicable for foreign tables. */ + if (rte == NULL || rte->relkind != RELKIND_FOREIGN_TABLE) + return false; + + rel = relation_open(rte->relid, NoLock); + + fdwroutine = GetFdwRoutineForRelation(rel, false); + + relation_close(rel, NoLock); + + /* Check if FDW supports late locking */ + if (fdwroutine && fdwroutine->RefetchForeignRow == NULL) + return true; + + return false; +} + /* * preprocess_limit - do pre-estimation for LIMIT and/or OFFSET clauses * -- 2.39.3 (Apple Git-146)