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Make tablesample work with partitioned tables.

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This was an oversight in the original partitioning commit.

Amit Langote, reviewed by David Fetter

Discussion: http://postgr.es/m/59af6590-8ace-04c4-c36c-ea35d435c60e@lab.ntt.co.jp
This commit is contained in:
Robert Haas
2017-02-24 12:21:46 +05:30
parent 6d493e1a01
commit 5dbdb2f799
3 changed files with 28 additions and 1 deletions
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3
src/backend/parser/parse_clause.c
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@@ -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"),

18
src/test/regress/expected/tablesample.out
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@@ -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;

8
src/test/regress/sql/tablesample.sql
View File

@@ -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;