From 45f10bd34077c17aaa8ea18a62d03a237ab1ac14 Mon Sep 17 00:00:00 2001 From: amit Date: Mon, 6 Feb 2017 17:26:48 +0900 Subject: [PATCH 3/3] Avoid creating scan nodes for partitioned tables Currently, we create scan nodes for inheritance parents in their role as an inheritance set member. Partitioned tables do not contain any data, so it's useless to create scan nodes for them. So we need not create AppendRelInfo's for them in the planner prep phase. Further, the planner prep phase turns off inheritance on the parent RTE if there isn't at least one child member (other than the parent itself which in normal cases is also a child member), which means the latter phases will not consider creating an Append plan and instead create a scan node. Avoid this if the RTE is a partitioned table, by noticing such cases in set_rel_size(). Per suggestion from Ashutosh Bapat. Next, since we do not add the RTE corresponding to the root partitioned table as the 1st child member of the inheritance set, inheritance_planner() must not assume the same when assigning nominalRelation to a ModifyTable node. --- src/backend/optimizer/path/allpaths.c | 8 +++ src/backend/optimizer/plan/planner.c | 14 +++- src/backend/optimizer/prep/prepunion.c | 24 ++++++- src/test/regress/expected/inherit.out | 124 +++++++++++---------------------- src/test/regress/sql/inherit.sql | 8 +++ 5 files changed, 90 insertions(+), 88 deletions(-) diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index 633b5c1608..f2c8d27193 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -342,6 +342,14 @@ set_rel_size(PlannerInfo *root, RelOptInfo *rel, /* Foreign table */ set_foreign_size(root, rel, rte); } + else if (rte->relkind == RELKIND_PARTITIONED_TABLE) + { + /* + * A partitioned table without leaf partitions is marked + * as a dummy rel. + */ + set_dummy_rel_pathlist(rel); + } else if (rte->tablesample != NULL) { /* Sampled relation */ diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c index ca0ae7883e..b5698f0ce7 100644 --- a/src/backend/optimizer/plan/planner.c +++ b/src/backend/optimizer/plan/planner.c @@ -996,10 +996,20 @@ inheritance_planner(PlannerInfo *root) RelOptInfo *final_rel; ListCell *lc; Index rti; + RangeTblEntry *parent_rte; Assert(parse->commandType != CMD_INSERT); /* + * If the parent RTE is a partitioned table, we should use that as the + * nominal relation, because we do not have the duplicate parent RTE, + * unlike in the case of a non-partitioned inheritance parent. + */ + parent_rte = rt_fetch(parentRTindex, root->parse->rtable); + if (parent_rte->relkind == RELKIND_PARTITIONED_TABLE) + nominalRelation = parentRTindex; + + /* * We generate a modified instance of the original Query for each target * relation, plan that, and put all the plans into a list that will be * controlled by a single ModifyTable node. All the instances share the @@ -1060,7 +1070,6 @@ inheritance_planner(PlannerInfo *root) { AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(lc); PlannerInfo *subroot; - RangeTblEntry *parent_rte; RangeTblEntry *child_rte; RelOptInfo *sub_final_rel; Path *subpath; @@ -1214,6 +1223,9 @@ inheritance_planner(PlannerInfo *root) * will not be otherwise referenced in the plan, doing so would give * rise to confusing use of multiple aliases in EXPLAIN output for * what the user will think is the "same" table.) + * + * If the parent is a partitioned table, we already set the nominal + * relation. */ if (nominalRelation < 0) nominalRelation = appinfo->child_relid; diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c index 1389db18ba..e31daf737b 100644 --- a/src/backend/optimizer/prep/prepunion.c +++ b/src/backend/optimizer/prep/prepunion.c @@ -1364,6 +1364,7 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti) List *inhOIDs; List *appinfos; ListCell *l; + int min_child_rels; /* Does RT entry allow inheritance? */ if (!rte->inh) @@ -1450,6 +1451,22 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti) newrelation = oldrelation; /* + * Ignore partitioned tables here, because we do not want them to + * be considered as child tables in the inheritance set. No scan + * plans will be created for them. + */ + if (newrelation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE) + { + /* + * Don't lose the lock taken for us by find_all_inheritors() + * lest its partitions change under us. + */ + if (newrelation != oldrelation) + heap_close(newrelation, NoLock); + continue; + } + + /* * It is possible that the parent table has children that are temp * tables of other backends. We cannot safely access such tables * (because of buffering issues), and the best thing to do seems to be @@ -1548,9 +1565,12 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti) * If all the children were temp tables, pretend it's a non-inheritance * situation. The duplicate RTE we added for the parent table is * harmless, so we don't bother to get rid of it; ditto for the useless - * PlanRowMark node. + * PlanRowMark node. Since we do not create appinfos for partitioned + * tables above, we may end up with just one appinfo corresponding to + * the only leaf partition, which is fine. */ - if (list_length(appinfos) < 2) + min_child_rels = (rte->relkind == RELKIND_PARTITIONED_TABLE ? 1 : 2); + if (list_length(appinfos) < min_child_rels) { /* Clear flag before returning */ rte->inh = false; diff --git a/src/test/regress/expected/inherit.out b/src/test/regress/expected/inherit.out index a8c8b28a75..55b147432f 100644 --- a/src/test/regress/expected/inherit.out +++ b/src/test/regress/expected/inherit.out @@ -1598,6 +1598,14 @@ reset enable_bitmapscan; create table list_parted ( a varchar ) partition by list (a); +-- test scanning partitioned table without any partitions +explain (costs off) select * from list_parted; + QUERY PLAN +-------------------------- + Result + One-Time Filter: false +(2 rows) + create table part_ab_cd partition of list_parted for values in ('ab', 'cd'); create table part_ef_gh partition of list_parted for values in ('ef', 'gh'); create table part_null_xy partition of list_parted for values in (null, 'xy'); @@ -1605,77 +1613,74 @@ explain (costs off) select * from list_parted; QUERY PLAN -------------------------------- Append - -> Seq Scan on list_parted -> Seq Scan on part_ab_cd -> Seq Scan on part_ef_gh -> Seq Scan on part_null_xy -(5 rows) +(4 rows) explain (costs off) select * from list_parted where a is null; QUERY PLAN -------------------------------- Append - -> Seq Scan on list_parted - Filter: (a IS NULL) -> Seq Scan on part_null_xy Filter: (a IS NULL) -(5 rows) +(3 rows) explain (costs off) select * from list_parted where a is not null; QUERY PLAN --------------------------------- Append - -> Seq Scan on list_parted - Filter: (a IS NOT NULL) -> Seq Scan on part_ab_cd Filter: (a IS NOT NULL) -> Seq Scan on part_ef_gh Filter: (a IS NOT NULL) -> Seq Scan on part_null_xy Filter: (a IS NOT NULL) -(9 rows) +(7 rows) explain (costs off) select * from list_parted where a in ('ab', 'cd', 'ef'); QUERY PLAN ---------------------------------------------------------- Append - -> Seq Scan on list_parted - Filter: ((a)::text = ANY ('{ab,cd,ef}'::text[])) -> Seq Scan on part_ab_cd Filter: ((a)::text = ANY ('{ab,cd,ef}'::text[])) -> Seq Scan on part_ef_gh Filter: ((a)::text = ANY ('{ab,cd,ef}'::text[])) -(7 rows) +(5 rows) explain (costs off) select * from list_parted where a = 'ab' or a in (null, 'cd'); QUERY PLAN --------------------------------------------------------------------------------------- Append - -> Seq Scan on list_parted - Filter: (((a)::text = 'ab'::text) OR ((a)::text = ANY ('{NULL,cd}'::text[]))) -> Seq Scan on part_ab_cd Filter: (((a)::text = 'ab'::text) OR ((a)::text = ANY ('{NULL,cd}'::text[]))) -> Seq Scan on part_ef_gh Filter: (((a)::text = 'ab'::text) OR ((a)::text = ANY ('{NULL,cd}'::text[]))) -> Seq Scan on part_null_xy Filter: (((a)::text = 'ab'::text) OR ((a)::text = ANY ('{NULL,cd}'::text[]))) -(9 rows) +(7 rows) explain (costs off) select * from list_parted where a = 'ab'; QUERY PLAN ------------------------------------------ Append - -> Seq Scan on list_parted - Filter: ((a)::text = 'ab'::text) -> Seq Scan on part_ab_cd Filter: ((a)::text = 'ab'::text) -(5 rows) +(3 rows) create table range_list_parted ( a int, b char(2) ) partition by range (a); create table part_1_10 partition of range_list_parted for values from (1) to (10) partition by list (b); +-- test scanning partitioned table without any leaf partitions +explain (costs off) select * from range_list_parted; + QUERY PLAN +-------------------------- + Result + One-Time Filter: false +(2 rows) + create table part_1_10_ab partition of part_1_10 for values in ('ab'); create table part_1_10_cd partition of part_1_10 for values in ('cd'); create table part_10_20 partition of range_list_parted for values from (10) to (20) partition by list (b); @@ -1689,14 +1694,9 @@ create table part_40_inf_ab partition of part_40_inf for values in ('ab'); create table part_40_inf_cd partition of part_40_inf for values in ('cd'); create table part_40_inf_null partition of part_40_inf for values in (null); explain (costs off) select * from range_list_parted; - QUERY PLAN -------------------------------------- + QUERY PLAN +------------------------------------ Append - -> Seq Scan on range_list_parted - -> Seq Scan on part_1_10 - -> Seq Scan on part_10_20 - -> Seq Scan on part_21_30 - -> Seq Scan on part_40_inf -> Seq Scan on part_1_10_ab -> Seq Scan on part_1_10_cd -> Seq Scan on part_10_20_ab @@ -1706,36 +1706,22 @@ explain (costs off) select * from range_list_parted; -> Seq Scan on part_40_inf_ab -> Seq Scan on part_40_inf_cd -> Seq Scan on part_40_inf_null -(15 rows) +(10 rows) explain (costs off) select * from range_list_parted where a = 5; - QUERY PLAN -------------------------------------- + QUERY PLAN +-------------------------------- Append - -> Seq Scan on range_list_parted - Filter: (a = 5) - -> Seq Scan on part_1_10 - Filter: (a = 5) -> Seq Scan on part_1_10_ab Filter: (a = 5) -> Seq Scan on part_1_10_cd Filter: (a = 5) -(9 rows) +(5 rows) explain (costs off) select * from range_list_parted where b = 'ab'; - QUERY PLAN -------------------------------------- + QUERY PLAN +------------------------------------ Append - -> Seq Scan on range_list_parted - Filter: (b = 'ab'::bpchar) - -> Seq Scan on part_1_10 - Filter: (b = 'ab'::bpchar) - -> Seq Scan on part_10_20 - Filter: (b = 'ab'::bpchar) - -> Seq Scan on part_21_30 - Filter: (b = 'ab'::bpchar) - -> Seq Scan on part_40_inf - Filter: (b = 'ab'::bpchar) -> Seq Scan on part_1_10_ab Filter: (b = 'ab'::bpchar) -> Seq Scan on part_10_20_ab @@ -1744,27 +1730,19 @@ explain (costs off) select * from range_list_parted where b = 'ab'; Filter: (b = 'ab'::bpchar) -> Seq Scan on part_40_inf_ab Filter: (b = 'ab'::bpchar) -(19 rows) +(9 rows) explain (costs off) select * from range_list_parted where a between 3 and 23 and b in ('ab'); QUERY PLAN ----------------------------------------------------------------- Append - -> Seq Scan on range_list_parted - Filter: ((a >= 3) AND (a <= 23) AND (b = 'ab'::bpchar)) - -> Seq Scan on part_1_10 - Filter: ((a >= 3) AND (a <= 23) AND (b = 'ab'::bpchar)) - -> Seq Scan on part_10_20 - Filter: ((a >= 3) AND (a <= 23) AND (b = 'ab'::bpchar)) - -> Seq Scan on part_21_30 - Filter: ((a >= 3) AND (a <= 23) AND (b = 'ab'::bpchar)) -> Seq Scan on part_1_10_ab Filter: ((a >= 3) AND (a <= 23) AND (b = 'ab'::bpchar)) -> Seq Scan on part_10_20_ab Filter: ((a >= 3) AND (a <= 23) AND (b = 'ab'::bpchar)) -> Seq Scan on part_21_30_ab Filter: ((a >= 3) AND (a <= 23) AND (b = 'ab'::bpchar)) -(15 rows) +(7 rows) /* Should select no rows because range partition key cannot be null */ explain (costs off) select * from range_list_parted where a is null; @@ -1776,37 +1754,17 @@ explain (costs off) select * from range_list_parted where a is null; /* Should only select rows from the null-accepting partition */ explain (costs off) select * from range_list_parted where b is null; - QUERY PLAN -------------------------------------- + QUERY PLAN +------------------------------------ Append - -> Seq Scan on range_list_parted - Filter: (b IS NULL) - -> Seq Scan on part_1_10 - Filter: (b IS NULL) - -> Seq Scan on part_10_20 - Filter: (b IS NULL) - -> Seq Scan on part_21_30 - Filter: (b IS NULL) - -> Seq Scan on part_40_inf - Filter: (b IS NULL) -> Seq Scan on part_40_inf_null Filter: (b IS NULL) -(13 rows) +(3 rows) explain (costs off) select * from range_list_parted where a is not null and a < 67; QUERY PLAN ------------------------------------------------ Append - -> Seq Scan on range_list_parted - Filter: ((a IS NOT NULL) AND (a < 67)) - -> Seq Scan on part_1_10 - Filter: ((a IS NOT NULL) AND (a < 67)) - -> Seq Scan on part_10_20 - Filter: ((a IS NOT NULL) AND (a < 67)) - -> Seq Scan on part_21_30 - Filter: ((a IS NOT NULL) AND (a < 67)) - -> Seq Scan on part_40_inf - Filter: ((a IS NOT NULL) AND (a < 67)) -> Seq Scan on part_1_10_ab Filter: ((a IS NOT NULL) AND (a < 67)) -> Seq Scan on part_1_10_cd @@ -1825,23 +1783,19 @@ explain (costs off) select * from range_list_parted where a is not null and a < Filter: ((a IS NOT NULL) AND (a < 67)) -> Seq Scan on part_40_inf_null Filter: ((a IS NOT NULL) AND (a < 67)) -(29 rows) +(19 rows) explain (costs off) select * from range_list_parted where a >= 30; - QUERY PLAN -------------------------------------- + QUERY PLAN +------------------------------------ Append - -> Seq Scan on range_list_parted - Filter: (a >= 30) - -> Seq Scan on part_40_inf - Filter: (a >= 30) -> Seq Scan on part_40_inf_ab Filter: (a >= 30) -> Seq Scan on part_40_inf_cd Filter: (a >= 30) -> Seq Scan on part_40_inf_null Filter: (a >= 30) -(11 rows) +(7 rows) drop table list_parted cascade; NOTICE: drop cascades to 3 other objects diff --git a/src/test/regress/sql/inherit.sql b/src/test/regress/sql/inherit.sql index a8b7eb1c8d..04cc4ffa23 100644 --- a/src/test/regress/sql/inherit.sql +++ b/src/test/regress/sql/inherit.sql @@ -570,6 +570,10 @@ reset enable_bitmapscan; create table list_parted ( a varchar ) partition by list (a); + +-- test scanning partitioned table without any partitions +explain (costs off) select * from list_parted; + create table part_ab_cd partition of list_parted for values in ('ab', 'cd'); create table part_ef_gh partition of list_parted for values in ('ef', 'gh'); create table part_null_xy partition of list_parted for values in (null, 'xy'); @@ -586,6 +590,10 @@ create table range_list_parted ( b char(2) ) partition by range (a); create table part_1_10 partition of range_list_parted for values from (1) to (10) partition by list (b); + +-- test scanning partitioned table without any leaf partitions +explain (costs off) select * from range_list_parted; + create table part_1_10_ab partition of part_1_10 for values in ('ab'); create table part_1_10_cd partition of part_1_10 for values in ('cd'); create table part_10_20 partition of range_list_parted for values from (10) to (20) partition by list (b); -- 2.11.0