tablesample with partitioned tables

From d9c412ea14b005b4c6013026c6c62eab97727c3c Mon Sep 17 00:00:00 2001
From: amit <amitlangote09@gmail.com>
Date: Wed, 22 Feb 2017 16:27:35 +0900
Subject: [PATCH] Partitioned tables support tablesample

---
 src/backend/parser/parse_clause.c         |  3 ++-
 src/test/regress/expected/tablesample.out | 18 ++++++++++++++++++
 src/test/regress/sql/tablesample.sql      |  8 ++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c
index fecc1d6598..b5eae56006 100644
--- a/src/backend/parser/parse_clause.c
+++ b/src/backend/parser/parse_clause.c
@@ -907,7 +907,8 @@ transformFromClauseItem(ParseState *pstate, Node *n,
 		rte = rt_fetch(rtr->rtindex, pstate->p_rtable);
 		/* We only support this on plain relations and matviews */
 		if (rte->relkind != RELKIND_RELATION &&
-			rte->relkind != RELKIND_MATVIEW)
+			rte->relkind != RELKIND_MATVIEW &&
+			rte->relkind != RELKIND_PARTITIONED_TABLE)
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("TABLESAMPLE clause can only be applied to tables and materialized views"),
diff --git a/src/test/regress/expected/tablesample.out b/src/test/regress/expected/tablesample.out
index 7e91b958ae..b18e420e9b 100644
--- a/src/test/regress/expected/tablesample.out
+++ b/src/test/regress/expected/tablesample.out
@@ -313,3 +313,21 @@ SELECT q.* FROM (SELECT * FROM test_tablesample) as q TABLESAMPLE BERNOULLI (5);
 ERROR:  syntax error at or near "TABLESAMPLE"
 LINE 1: ...CT q.* FROM (SELECT * FROM test_tablesample) as q TABLESAMPL...
                                                              ^
+-- check partitioned tables support tablesample
+create table parted_sample (a int) partition by list (a);
+create table parted_sample_1 partition of parted_sample for values in (1);
+create table parted_sample_2 partition of parted_sample for values in (2);
+explain (costs off)
+  select * from parted_sample tablesample bernoulli (100);
+                QUERY PLAN                 
+-------------------------------------------
+ Append
+   ->  Sample Scan on parted_sample
+         Sampling: bernoulli ('100'::real)
+   ->  Sample Scan on parted_sample_1
+         Sampling: bernoulli ('100'::real)
+   ->  Sample Scan on parted_sample_2
+         Sampling: bernoulli ('100'::real)
+(7 rows)
+
+drop table parted_sample, parted_sample_1, parted_sample_2;
diff --git a/src/test/regress/sql/tablesample.sql b/src/test/regress/sql/tablesample.sql
index eec9793496..c39fe4b750 100644
--- a/src/test/regress/sql/tablesample.sql
+++ b/src/test/regress/sql/tablesample.sql
@@ -100,3 +100,11 @@ WITH query_select AS (SELECT * FROM test_tablesample)
 SELECT * FROM query_select TABLESAMPLE BERNOULLI (5.5) REPEATABLE (1);
 
 SELECT q.* FROM (SELECT * FROM test_tablesample) as q TABLESAMPLE BERNOULLI (5);
+
+-- check partitioned tables support tablesample
+create table parted_sample (a int) partition by list (a);
+create table parted_sample_1 partition of parted_sample for values in (1);
+create table parted_sample_2 partition of parted_sample for values in (2);
+explain (costs off)
+  select * from parted_sample tablesample bernoulli (100);
+drop table parted_sample, parted_sample_1, parted_sample_2;
-- 
2.11.0