Fix unstable scan rows caused by limit squelch.

Squelch in limit node may cause scan finish early, row count in scan may vary.

Signed-off-by: Dongxiao Song <songdongxiao@hashdata.cn>

Author: Dongxiao Song

src/test/regress/expected/gp_explain.out

@@ -577,6 +577,10 @@ DROP USER regress_range_parted_user;
 -- Test if explain analyze will hang with materialize node
 CREATE TABLE recursive_table_ic (a INT) DISTRIBUTED BY (a);
 INSERT INTO recursive_table_ic SELECT * FROM generate_series(20, 30000);
+-- start_matchsubs
+-- m/Seq Scan on recursive_table_ic \(actual rows=\d+ loops=1\)/
+-- s/Seq Scan on recursive_table_ic \(actual rows=\d+ loops=1\)/Seq Scan on recursive_table_ic (actual rows=#### loops=1)/
+-- end_matchsubs
 explain (analyze, costs off, timing off, summary off) WITH RECURSIVE
 r(i) AS (
 	SELECT 1
@@ -600,7 +604,7 @@ SELECT * FROM y LIMIT 10;
                      ->  WorkTable Scan on y (never executed)
                      ->  Materialize (never executed)
                            ->  Gather Motion 3:1  (slice1; segments: 3) (never executed)
-                                 ->  Seq Scan on recursive_table_ic (actual rows=4061 loops=1)
+                                 ->  Seq Scan on recursive_table_ic (actual rows=#### loops=1)
  Optimizer: Postgres query optimizer
 (13 rows)
 

src/test/regress/expected/gp_explain_optimizer.out

@@ -599,6 +599,10 @@ DROP USER regress_range_parted_user;
 -- Test if explain analyze will hang with materialize node
 CREATE TABLE recursive_table_ic (a INT) DISTRIBUTED BY (a);
 INSERT INTO recursive_table_ic SELECT * FROM generate_series(20, 30000);
+-- start_matchsubs
+-- m/Seq Scan on recursive_table_ic \(actual rows=\d+ loops=1\)/
+-- s/Seq Scan on recursive_table_ic \(actual rows=\d+ loops=1\)/Seq Scan on recursive_table_ic (actual rows=#### loops=1)/
+-- end_matchsubs
 explain (analyze, costs off, timing off, summary off) WITH RECURSIVE
 r(i) AS (
 	SELECT 1
@@ -622,7 +626,7 @@ SELECT * FROM y LIMIT 10;
                      ->  WorkTable Scan on y (never executed)
                      ->  Materialize (never executed)
                            ->  Gather Motion 3:1  (slice1; segments: 3) (never executed)
-                                 ->  Seq Scan on recursive_table_ic (actual rows=4061 loops=1)
+                                 ->  Seq Scan on recursive_table_ic (actual rows=#### loops=1)
  Optimizer: Postgres query optimizer
 (13 rows)
 

src/test/regress/sql/gp_explain.sql

@@ -285,7 +285,10 @@ DROP USER regress_range_parted_user;
 -- Test if explain analyze will hang with materialize node
 CREATE TABLE recursive_table_ic (a INT) DISTRIBUTED BY (a);
 INSERT INTO recursive_table_ic SELECT * FROM generate_series(20, 30000);
-
+-- start_matchsubs
+-- m/Seq Scan on recursive_table_ic \(actual rows=\d+ loops=1\)/
+-- s/Seq Scan on recursive_table_ic \(actual rows=\d+ loops=1\)/Seq Scan on recursive_table_ic (actual rows=#### loops=1)/
+-- end_matchsubs
 explain (analyze, costs off, timing off, summary off) WITH RECURSIVE
 r(i) AS (
 	SELECT 1