Redesign tablesample method API, and do extensive code review.

The original implementation of TABLESAMPLE modeled the tablesample method
API on index access methods, which wasn't a good choice because, without
specialized DDL commands, there's no way to build an extension that can
implement a TSM.  (Raw inserts into system catalogs are not an acceptable
thing to do, because we can't undo them during DROP EXTENSION, nor will
pg_upgrade behave sanely.)  Instead adopt an API more like procedural
language handlers or foreign data wrappers, wherein the only SQL-level
support object needed is a single handler function identified by having
a special return type.  This lets us get rid of the supporting catalog
altogether, so that no custom DDL support is needed for the feature.

Adjust the API so that it can support non-constant tablesample arguments
(the original coding assumed we could evaluate the argument expressions at
ExecInitSampleScan time, which is undesirable even if it weren't outright
unsafe), and discourage sampling methods from looking at invisible tuples.
Make sure that the BERNOULLI and SYSTEM methods are genuinely repeatable
within and across queries, as required by the SQL standard, and deal more
honestly with methods that can't support that requirement.

Make a full code-review pass over the tablesample additions, and fix
assorted bugs, omissions, infelicities, and cosmetic issues (such as
failure to put the added code stanzas in a consistent ordering).
Improve EXPLAIN's output of tablesample plans, too.

Back-patch to 9.5 so that we don't have to support the original API
in production.

8 files changed, 271 insertions, 147 deletions

diff --git a/src/test/regress/expected/rowsecurity.out b/src/test/regress/expected/rowsecurity.out
index 414299a6941..e7c242cd22d 100644
--- a/src/test/regress/expected/rowsecurity.out
+++ b/src/test/regress/expected/rowsecurity.out
@@ -101,15 +101,17 @@ NOTICE:  f_leak => great manga
   44 |   8 |      1 | rls_regress_user2 | great manga           | manga
 (4 rows)
 
-SELECT * FROM document TABLESAMPLE BERNOULLI (50) REPEATABLE(1) WHERE f_leak(dtitle) ORDER BY did;
-NOTICE:  f_leak => my first novel
+-- try a sampled version
+SELECT * FROM document TABLESAMPLE BERNOULLI(50) REPEATABLE(0)
+  WHERE f_leak(dtitle) ORDER BY did;
 NOTICE:  f_leak => my first manga
 NOTICE:  f_leak => great science fiction
+NOTICE:  f_leak => great manga
  did | cid | dlevel |      dauthor      |        dtitle         
 -----+-----+--------+-------------------+-----------------------
-   1 |  11 |      1 | rls_regress_user1 | my first novel
    4 |  44 |      1 | rls_regress_user1 | my first manga
    6 |  22 |      1 | rls_regress_user2 | great science fiction
+   8 |  44 |      1 | rls_regress_user2 | great manga
 (3 rows)
 
 -- viewpoint from rls_regress_user2
@@ -156,20 +158,20 @@ NOTICE:  f_leak => great manga
   44 |   8 |      1 | rls_regress_user2 | great manga           | manga
 (8 rows)
 
-SELECT * FROM document TABLESAMPLE BERNOULLI (50) REPEATABLE(1) WHERE f_leak(dtitle) ORDER BY did;
-NOTICE:  f_leak => my first novel
-NOTICE:  f_leak => my second novel
+-- try a sampled version
+SELECT * FROM document TABLESAMPLE BERNOULLI(50) REPEATABLE(0)
+  WHERE f_leak(dtitle) ORDER BY did;
 NOTICE:  f_leak => my first manga
+NOTICE:  f_leak => my second manga
 NOTICE:  f_leak => great science fiction
-NOTICE:  f_leak => great technology book
+NOTICE:  f_leak => great manga
  did | cid | dlevel |      dauthor      |        dtitle         
 -----+-----+--------+-------------------+-----------------------
-   1 |  11 |      1 | rls_regress_user1 | my first novel
-   2 |  11 |      2 | rls_regress_user1 | my second novel
    4 |  44 |      1 | rls_regress_user1 | my first manga
+   5 |  44 |      2 | rls_regress_user1 | my second manga
    6 |  22 |      1 | rls_regress_user2 | great science fiction
-   7 |  33 |      2 | rls_regress_user2 | great technology book
-(5 rows)
+   8 |  44 |      1 | rls_regress_user2 | great manga
+(4 rows)
 
 EXPLAIN (COSTS OFF) SELECT * FROM document WHERE f_leak(dtitle);
                         QUERY PLAN                        
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index cd5337531d4..1e5b0b9a2c4 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2202,6 +2202,10 @@ street| SELECT r.name,
    FROM ONLY road r,
     real_city c
   WHERE (c.outline ## r.thepath);
+test_tablesample_v1| SELECT test_tablesample.id
+   FROM test_tablesample TABLESAMPLE system ((10 * 2)) REPEATABLE (2);
+test_tablesample_v2| SELECT test_tablesample.id
+   FROM test_tablesample TABLESAMPLE system (99);
 toyemp| SELECT emp.name,
     emp.age,
     emp.location,
diff --git a/src/test/regress/expected/sanity_check.out b/src/test/regress/expected/sanity_check.out
index 14acd16da3b..eb0bc88ef1f 100644
--- a/src/test/regress/expected/sanity_check.out
+++ b/src/test/regress/expected/sanity_check.out
@@ -128,7 +128,6 @@ pg_shdepend|t
 pg_shdescription|t
 pg_shseclabel|t
 pg_statistic|t
-pg_tablesample_method|t
 pg_tablespace|t
 pg_transform|t
 pg_trigger|t
diff --git a/src/test/regress/expected/tablesample.out b/src/test/regress/expected/tablesample.out
index 04e5eb8b807..727a8354397 100644
--- a/src/test/regress/expected/tablesample.out
+++ b/src/test/regress/expected/tablesample.out
@@ -1,107 +1,123 @@
-CREATE TABLE test_tablesample (id int, name text) WITH (fillfactor=10); -- force smaller pages so we don't have to load too much data to get multiple pages
-INSERT INTO test_tablesample SELECT i, repeat(i::text, 200) FROM generate_series(0, 9) s(i) ORDER BY i;
-SELECT t.id FROM test_tablesample AS t TABLESAMPLE SYSTEM (50) REPEATABLE (10);
+CREATE TABLE test_tablesample (id int, name text) WITH (fillfactor=10);
+-- use fillfactor so we don't have to load too much data to get multiple pages
+INSERT INTO test_tablesample
+  SELECT i, repeat(i::text, 200) FROM generate_series(0, 9) s(i);
+SELECT t.id FROM test_tablesample AS t TABLESAMPLE SYSTEM (50) REPEATABLE (0);
  id 
 ----
-  0
-  1
-  2
   3
   4
   5
-  9
-(7 rows)
-
-SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (100.0/11) REPEATABLE (9999);
- id 
-----
   6
   7
   8
-(3 rows)
+(6 rows)
 
-SELECT count(*) FROM test_tablesample TABLESAMPLE SYSTEM (100);
- count 
--------
-    10
-(1 row)
+SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (100.0/11) REPEATABLE (0);
+ id 
+----
+(0 rows)
 
-SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (100);
+SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (0);
  id 
 ----
-  0
-  1
-  2
+  3
+  4
+  5
   6
   7
   8
-  9
-(7 rows)
+(6 rows)
 
-SELECT id FROM test_tablesample TABLESAMPLE BERNOULLI (50) REPEATABLE (100);
+SELECT id FROM test_tablesample TABLESAMPLE BERNOULLI (50) REPEATABLE (0);
  id 
 ----
-  0
-  1
-  3
   4
   5
+  6
+  7
+  8
 (5 rows)
 
-SELECT id FROM test_tablesample TABLESAMPLE BERNOULLI (5.5) REPEATABLE (1);
+SELECT id FROM test_tablesample TABLESAMPLE BERNOULLI (5.5) REPEATABLE (0);
  id 
 ----
-  0
-  5
-(2 rows)
+  7
+(1 row)
 
-CREATE VIEW test_tablesample_v1 AS SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (10*2) REPEATABLE (2);
-CREATE VIEW test_tablesample_v2 AS SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (99);
-SELECT pg_get_viewdef('test_tablesample_v1'::regclass);
-                                 pg_get_viewdef                                 
---------------------------------------------------------------------------------
-  SELECT test_tablesample.id                                                   +
-    FROM test_tablesample TABLESAMPLE system (((10 * 2))::real) REPEATABLE (2);
+-- 100% should give repeatable count results (ie, all rows) in any case
+SELECT count(*) FROM test_tablesample TABLESAMPLE SYSTEM (100);
+ count 
+-------
+    10
 (1 row)
 
-SELECT pg_get_viewdef('test_tablesample_v2'::regclass);
-                      pg_get_viewdef                       
------------------------------------------------------------
-  SELECT test_tablesample.id                              +
-    FROM test_tablesample TABLESAMPLE system ((99)::real);
+SELECT count(*) FROM test_tablesample TABLESAMPLE SYSTEM (100) REPEATABLE (1+2);
+ count 
+-------
+    10
+(1 row)
+
+SELECT count(*) FROM test_tablesample TABLESAMPLE SYSTEM (100) REPEATABLE (0.4);
+ count 
+-------
+    10
 (1 row)
 
+CREATE VIEW test_tablesample_v1 AS
+  SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (10*2) REPEATABLE (2);
+CREATE VIEW test_tablesample_v2 AS
+  SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (99);
+\d+ test_tablesample_v1
+          View "public.test_tablesample_v1"
+ Column |  Type   | Modifiers | Storage | Description 
+--------+---------+-----------+---------+-------------
+ id     | integer |           | plain   | 
+View definition:
+ SELECT test_tablesample.id
+   FROM test_tablesample TABLESAMPLE system ((10 * 2)) REPEATABLE (2);
+
+\d+ test_tablesample_v2
+          View "public.test_tablesample_v2"
+ Column |  Type   | Modifiers | Storage | Description 
+--------+---------+-----------+---------+-------------
+ id     | integer |           | plain   | 
+View definition:
+ SELECT test_tablesample.id
+   FROM test_tablesample TABLESAMPLE system (99);
+
+-- check a sampled query doesn't affect cursor in progress
 BEGIN;
-DECLARE tablesample_cur CURSOR FOR SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (100);
+DECLARE tablesample_cur CURSOR FOR
+  SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (0);
 FETCH FIRST FROM tablesample_cur;
  id 
 ----
-  0
+  3
 (1 row)
 
 FETCH NEXT FROM tablesample_cur;
  id 
 ----
-  1
+  4
 (1 row)
 
 FETCH NEXT FROM tablesample_cur;
  id 
 ----
-  2
+  5
 (1 row)
 
-SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (10);
+SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (0);
  id 
 ----
-  0
-  1
-  2
   3
   4
   5
-  9
-(7 rows)
+  6
+  7
+  8
+(6 rows)
 
 FETCH NEXT FROM tablesample_cur;
  id 
@@ -124,19 +140,19 @@ FETCH NEXT FROM tablesample_cur;
 FETCH FIRST FROM tablesample_cur;
  id 
 ----
-  0
+  3
 (1 row)
 
 FETCH NEXT FROM tablesample_cur;
  id 
 ----
-  1
+  4
 (1 row)
 
 FETCH NEXT FROM tablesample_cur;
  id 
 ----
-  2
+  5
 (1 row)
 
 FETCH NEXT FROM tablesample_cur;
@@ -159,41 +175,129 @@ FETCH NEXT FROM tablesample_cur;
 
 CLOSE tablesample_cur;
 END;
-EXPLAIN SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (10);
-                                  QUERY PLAN                                   
--------------------------------------------------------------------------------
- Sample Scan (system) on test_tablesample  (cost=0.00..26.35 rows=635 width=4)
+EXPLAIN (COSTS OFF)
+  SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (2);
+                             QUERY PLAN                             
+--------------------------------------------------------------------
+ Sample Scan on test_tablesample
+   Sampling: system ('50'::real) REPEATABLE ('2'::double precision)
+(2 rows)
+
+EXPLAIN (COSTS OFF)
+  SELECT * FROM test_tablesample_v1;
+                             QUERY PLAN                             
+--------------------------------------------------------------------
+ Sample Scan on test_tablesample
+   Sampling: system ('20'::real) REPEATABLE ('2'::double precision)
+(2 rows)
+
+-- check inheritance behavior
+explain (costs off)
+  select count(*) from person tablesample bernoulli (100);
+                   QUERY PLAN                    
+-------------------------------------------------
+ Aggregate
+   ->  Append
+         ->  Sample Scan on person
+               Sampling: bernoulli ('100'::real)
+         ->  Sample Scan on emp
+               Sampling: bernoulli ('100'::real)
+         ->  Sample Scan on student
+               Sampling: bernoulli ('100'::real)
+         ->  Sample Scan on stud_emp
+               Sampling: bernoulli ('100'::real)
+(10 rows)
+
+select count(*) from person tablesample bernoulli (100);
+ count 
+-------
+    58
 (1 row)
 
-EXPLAIN SELECT * FROM test_tablesample_v1;
-                                  QUERY PLAN                                   
--------------------------------------------------------------------------------
- Sample Scan (system) on test_tablesample  (cost=0.00..10.54 rows=254 width=4)
+select count(*) from person;
+ count 
+-------
+    58
+(1 row)
+
+-- check that collations get assigned within the tablesample arguments
+SELECT count(*) FROM test_tablesample TABLESAMPLE bernoulli (('1'::text < '0'::text)::int);
+ count 
+-------
+     0
+(1 row)
+
+-- check behavior during rescans, as well as correct handling of min/max pct
+select * from
+  (values (0),(100)) v(pct),
+  lateral (select count(*) from tenk1 tablesample bernoulli (pct)) ss;
+ pct | count 
+-----+-------
+   0 |     0
+ 100 | 10000
+(2 rows)
+
+select * from
+  (values (0),(100)) v(pct),
+  lateral (select count(*) from tenk1 tablesample system (pct)) ss;
+ pct | count 
+-----+-------
+   0 |     0
+ 100 | 10000
+(2 rows)
+
+explain (costs off)
+select pct, count(unique1) from
+  (values (0),(100)) v(pct),
+  lateral (select * from tenk1 tablesample bernoulli (pct)) ss
+  group by pct;
+                       QUERY PLAN                       
+--------------------------------------------------------
+ HashAggregate
+   Group Key: "*VALUES*".column1
+   ->  Nested Loop
+         ->  Values Scan on "*VALUES*"
+         ->  Sample Scan on tenk1
+               Sampling: bernoulli ("*VALUES*".column1)
+(6 rows)
+
+select pct, count(unique1) from
+  (values (0),(100)) v(pct),
+  lateral (select * from tenk1 tablesample bernoulli (pct)) ss
+  group by pct;
+ pct | count 
+-----+-------
+ 100 | 10000
+(1 row)
+
+select pct, count(unique1) from
+  (values (0),(100)) v(pct),
+  lateral (select * from tenk1 tablesample system (pct)) ss
+  group by pct;
+ pct | count 
+-----+-------
+ 100 | 10000
 (1 row)
 
 -- errors
 SELECT id FROM test_tablesample TABLESAMPLE FOOBAR (1);
-ERROR:  tablesample method "foobar" does not exist
+ERROR:  tablesample method foobar does not exist
 LINE 1: SELECT id FROM test_tablesample TABLESAMPLE FOOBAR (1);
-                       ^
+                                                    ^
+SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (NULL);
+ERROR:  TABLESAMPLE parameter cannot be null
 SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (NULL);
-ERROR:  REPEATABLE clause must be NOT NULL numeric value
-LINE 1: ... test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (NULL);
-                                                                 ^
+ERROR:  TABLESAMPLE REPEATABLE parameter cannot be null
 SELECT id FROM test_tablesample TABLESAMPLE BERNOULLI (-1);
-ERROR:  invalid sample size
-HINT:  Sample size must be numeric value between 0 and 100 (inclusive).
+ERROR:  sample percentage must be between 0 and 100
 SELECT id FROM test_tablesample TABLESAMPLE BERNOULLI (200);
-ERROR:  invalid sample size
-HINT:  Sample size must be numeric value between 0 and 100 (inclusive).
+ERROR:  sample percentage must be between 0 and 100
 SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (-1);
-ERROR:  invalid sample size
-HINT:  Sample size must be numeric value between 0 and 100 (inclusive).
+ERROR:  sample percentage must be between 0 and 100
 SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (200);
-ERROR:  invalid sample size
-HINT:  Sample size must be numeric value between 0 and 100 (inclusive).
+ERROR:  sample percentage must be between 0 and 100
 SELECT id FROM test_tablesample_v1 TABLESAMPLE BERNOULLI (1);
-ERROR:  TABLESAMPLE clause can only be used on tables and materialized views
+ERROR:  TABLESAMPLE clause can only be applied to tables and materialized views
 LINE 1: SELECT id FROM test_tablesample_v1 TABLESAMPLE BERNOULLI (1)...
                        ^
 INSERT INTO test_tablesample_v1 VALUES(1);
@@ -202,30 +306,10 @@ DETAIL:  Views containing TABLESAMPLE are not automatically updatable.
 HINT:  To enable inserting into the view, provide an INSTEAD OF INSERT trigger or an unconditional ON INSERT DO INSTEAD rule.
 WITH query_select AS (SELECT * FROM test_tablesample)
 SELECT * FROM query_select TABLESAMPLE BERNOULLI (5.5) REPEATABLE (1);
-ERROR:  TABLESAMPLE clause can only be used on tables and materialized views
+ERROR:  TABLESAMPLE clause can only be applied to tables and materialized views
 LINE 2: SELECT * FROM query_select TABLESAMPLE BERNOULLI (5.5) REPEA...
                       ^
 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...
                                                              ^
--- catalog sanity
-SELECT *
-FROM pg_tablesample_method
-WHERE tsminit IS NULL
-   OR tsmseqscan IS NULL
-   OR tsmpagemode IS NULL
-   OR tsmnextblock IS NULL
-   OR tsmnexttuple IS NULL
-   OR tsmend IS NULL
-   OR tsmreset IS NULL
-   OR tsmcost IS NULL;
- tsmname | tsmseqscan | tsmpagemode | tsminit | tsmnextblock | tsmnexttuple | tsmexaminetuple | tsmend | tsmreset | tsmcost 
----------+------------+-------------+---------+--------------+--------------+-----------------+--------+----------+---------
-(0 rows)
-
--- done
-DROP TABLE test_tablesample CASCADE;
-NOTICE:  drop cascades to 2 other objects
-DETAIL:  drop cascades to view test_tablesample_v1
-drop cascades to view test_tablesample_v2
diff --git a/src/test/regress/output/misc.source b/src/test/regress/output/misc.source
index 70c9cc356a6..9eedb363d06 100644
--- a/src/test/regress/output/misc.source
+++ b/src/test/regress/output/misc.source
@@ -686,6 +686,9 @@ SELECT user_relns() AS user_relns
  test_range_excl
  test_range_gist
  test_range_spgist
+ test_tablesample
+ test_tablesample_v1
+ test_tablesample_v2
  test_tsvector
  testjsonb
  text_tbl
@@ -705,7 +708,7 @@ SELECT user_relns() AS user_relns
  tvvmv
  varchar_tbl
  xacttest
-(127 rows)
+(130 rows)
 
 SELECT name(equipment(hobby_construct(text 'skywalking', text 'mer')));
  name 
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index 3a607cff46c..15d74d4e6eb 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -110,6 +110,7 @@ test: lock
 test: replica_identity
 test: rowsecurity
 test: object_address
+test: tablesample
 test: alter_generic
 test: alter_operator
 test: misc
@@ -156,4 +157,3 @@ test: with
 test: xml
 test: event_trigger
 test: stats
-test: tablesample
diff --git a/src/test/regress/sql/rowsecurity.sql b/src/test/regress/sql/rowsecurity.sql
index 039070b85b7..e86f8143142 100644
--- a/src/test/regress/sql/rowsecurity.sql
+++ b/src/test/regress/sql/rowsecurity.sql
@@ -94,14 +94,18 @@ SET row_security TO ON;
 SELECT * FROM document WHERE f_leak(dtitle) ORDER BY did;
 SELECT * FROM document NATURAL JOIN category WHERE f_leak(dtitle) ORDER BY did;
 
-SELECT * FROM document TABLESAMPLE BERNOULLI (50) REPEATABLE(1) WHERE f_leak(dtitle) ORDER BY did;
+-- try a sampled version
+SELECT * FROM document TABLESAMPLE BERNOULLI(50) REPEATABLE(0)
+  WHERE f_leak(dtitle) ORDER BY did;
 
 -- viewpoint from rls_regress_user2
 SET SESSION AUTHORIZATION rls_regress_user2;
 SELECT * FROM document WHERE f_leak(dtitle) ORDER BY did;
 SELECT * FROM document NATURAL JOIN category WHERE f_leak(dtitle) ORDER BY did;
 
-SELECT * FROM document TABLESAMPLE BERNOULLI (50) REPEATABLE(1) WHERE f_leak(dtitle) ORDER BY did;
+-- try a sampled version
+SELECT * FROM document TABLESAMPLE BERNOULLI(50) REPEATABLE(0)
+  WHERE f_leak(dtitle) ORDER BY did;
 
 EXPLAIN (COSTS OFF) SELECT * FROM document WHERE f_leak(dtitle);
 EXPLAIN (COSTS OFF) SELECT * FROM document NATURAL JOIN category WHERE f_leak(dtitle);
diff --git a/src/test/regress/sql/tablesample.sql b/src/test/regress/sql/tablesample.sql
index 7b3eb9bedf7..eec97934966 100644
--- a/src/test/regress/sql/tablesample.sql
+++ b/src/test/regress/sql/tablesample.sql
@@ -1,26 +1,37 @@
-CREATE TABLE test_tablesample (id int, name text) WITH (fillfactor=10); -- force smaller pages so we don't have to load too much data to get multiple pages
+CREATE TABLE test_tablesample (id int, name text) WITH (fillfactor=10);
+-- use fillfactor so we don't have to load too much data to get multiple pages
 
-INSERT INTO test_tablesample SELECT i, repeat(i::text, 200) FROM generate_series(0, 9) s(i) ORDER BY i;
+INSERT INTO test_tablesample
+  SELECT i, repeat(i::text, 200) FROM generate_series(0, 9) s(i);
 
-SELECT t.id FROM test_tablesample AS t TABLESAMPLE SYSTEM (50) REPEATABLE (10);
-SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (100.0/11) REPEATABLE (9999);
+SELECT t.id FROM test_tablesample AS t TABLESAMPLE SYSTEM (50) REPEATABLE (0);
+SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (100.0/11) REPEATABLE (0);
+SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (0);
+SELECT id FROM test_tablesample TABLESAMPLE BERNOULLI (50) REPEATABLE (0);
+SELECT id FROM test_tablesample TABLESAMPLE BERNOULLI (5.5) REPEATABLE (0);
+
+-- 100% should give repeatable count results (ie, all rows) in any case
 SELECT count(*) FROM test_tablesample TABLESAMPLE SYSTEM (100);
-SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (100);
-SELECT id FROM test_tablesample TABLESAMPLE BERNOULLI (50) REPEATABLE (100);
-SELECT id FROM test_tablesample TABLESAMPLE BERNOULLI (5.5) REPEATABLE (1);
+SELECT count(*) FROM test_tablesample TABLESAMPLE SYSTEM (100) REPEATABLE (1+2);
+SELECT count(*) FROM test_tablesample TABLESAMPLE SYSTEM (100) REPEATABLE (0.4);
 
-CREATE VIEW test_tablesample_v1 AS SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (10*2) REPEATABLE (2);
-CREATE VIEW test_tablesample_v2 AS SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (99);
-SELECT pg_get_viewdef('test_tablesample_v1'::regclass);
-SELECT pg_get_viewdef('test_tablesample_v2'::regclass);
+CREATE VIEW test_tablesample_v1 AS
+  SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (10*2) REPEATABLE (2);
+CREATE VIEW test_tablesample_v2 AS
+  SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (99);
+\d+ test_tablesample_v1
+\d+ test_tablesample_v2
 
+-- check a sampled query doesn't affect cursor in progress
 BEGIN;
-DECLARE tablesample_cur CURSOR FOR SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (100);
+DECLARE tablesample_cur CURSOR FOR
+  SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (0);
+
 FETCH FIRST FROM tablesample_cur;
 FETCH NEXT FROM tablesample_cur;
 FETCH NEXT FROM tablesample_cur;
 
-SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (10);
+SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (0);
 
 FETCH NEXT FROM tablesample_cur;
 FETCH NEXT FROM tablesample_cur;
@@ -36,12 +47,45 @@ FETCH NEXT FROM tablesample_cur;
 CLOSE tablesample_cur;
 END;
 
-EXPLAIN SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (10);
-EXPLAIN SELECT * FROM test_tablesample_v1;
+EXPLAIN (COSTS OFF)
+  SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (2);
+EXPLAIN (COSTS OFF)
+  SELECT * FROM test_tablesample_v1;
+
+-- check inheritance behavior
+explain (costs off)
+  select count(*) from person tablesample bernoulli (100);
+select count(*) from person tablesample bernoulli (100);
+select count(*) from person;
+
+-- check that collations get assigned within the tablesample arguments
+SELECT count(*) FROM test_tablesample TABLESAMPLE bernoulli (('1'::text < '0'::text)::int);
+
+-- check behavior during rescans, as well as correct handling of min/max pct
+select * from
+  (values (0),(100)) v(pct),
+  lateral (select count(*) from tenk1 tablesample bernoulli (pct)) ss;
+select * from
+  (values (0),(100)) v(pct),
+  lateral (select count(*) from tenk1 tablesample system (pct)) ss;
+explain (costs off)
+select pct, count(unique1) from
+  (values (0),(100)) v(pct),
+  lateral (select * from tenk1 tablesample bernoulli (pct)) ss
+  group by pct;
+select pct, count(unique1) from
+  (values (0),(100)) v(pct),
+  lateral (select * from tenk1 tablesample bernoulli (pct)) ss
+  group by pct;
+select pct, count(unique1) from
+  (values (0),(100)) v(pct),
+  lateral (select * from tenk1 tablesample system (pct)) ss
+  group by pct;
 
 -- errors
 SELECT id FROM test_tablesample TABLESAMPLE FOOBAR (1);
 
+SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (NULL);
 SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (50) REPEATABLE (NULL);
 
 SELECT id FROM test_tablesample TABLESAMPLE BERNOULLI (-1);
@@ -56,19 +100,3 @@ 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);
-
--- catalog sanity
-
-SELECT *
-FROM pg_tablesample_method
-WHERE tsminit IS NULL
-   OR tsmseqscan IS NULL
-   OR tsmpagemode IS NULL
-   OR tsmnextblock IS NULL
-   OR tsmnexttuple IS NULL
-   OR tsmend IS NULL
-   OR tsmreset IS NULL
-   OR tsmcost IS NULL;
-
--- done
-DROP TABLE test_tablesample CASCADE;