4 files changed, 137 insertions, 0 deletions
diff --git a/src/test/regress/expected/fsm.out b/src/test/regress/expected/fsm.out
new file mode 100644
index 00000000000..df6b15b9d2a
--- /dev/null
+++ b/src/test/regress/expected/fsm.out
@@ -0,0 +1,75 @@
+--
+-- Free Space Map test
+--
+CREATE TABLE fsm_check_size (num int, str text);
+-- Fill 3 blocks with as many large records as will fit
+-- No FSM
+INSERT INTO fsm_check_size SELECT i, rpad('', 1024, 'a')
+FROM generate_series(1,7*3) i;
+VACUUM fsm_check_size;
+SELECT pg_relation_size('fsm_check_size', 'main') AS heap_size,
+pg_relation_size('fsm_check_size', 'fsm') AS fsm_size;
+ heap_size | fsm_size 
+-----------+----------
+     24576 |        0
+(1 row)
+
+-- Clear some space on block 0
+DELETE FROM fsm_check_size WHERE num <= 5;
+VACUUM fsm_check_size;
+-- Insert small record in block 2 to set the cached smgr targetBlock
+INSERT INTO fsm_check_size VALUES(99, 'b');
+-- Insert large record and make sure it goes in block 0 rather than
+-- causing the relation to extend
+INSERT INTO fsm_check_size VALUES (101, rpad('', 1024, 'a'));
+SELECT pg_relation_size('fsm_check_size', 'main') AS heap_size,
+pg_relation_size('fsm_check_size', 'fsm') AS fsm_size;
+ heap_size | fsm_size 
+-----------+----------
+     24576 |        0
+(1 row)
+
+-- Extend table with enough blocks to exceed the FSM threshold
+-- FSM is created and extended to 3 blocks
+INSERT INTO fsm_check_size SELECT i, 'c' FROM generate_series(200,1200) i;
+VACUUM fsm_check_size;
+SELECT pg_relation_size('fsm_check_size', 'fsm') AS fsm_size;
+ fsm_size 
+----------
+    24576
+(1 row)
+
+-- Truncate heap to 1 block
+-- No change in FSM
+DELETE FROM fsm_check_size WHERE num > 7;
+VACUUM fsm_check_size;
+SELECT pg_relation_size('fsm_check_size', 'fsm') AS fsm_size;
+ fsm_size 
+----------
+    24576
+(1 row)
+
+-- Truncate heap to 0 blocks
+-- FSM now truncated to 2 blocks
+DELETE FROM fsm_check_size;
+VACUUM fsm_check_size;
+SELECT pg_relation_size('fsm_check_size', 'fsm') AS fsm_size;
+ fsm_size 
+----------
+    16384
+(1 row)
+
+-- Add long random string to extend TOAST table to 1 block
+INSERT INTO fsm_check_size
+VALUES(0, (SELECT string_agg(md5(chr(i)), '')
+		   FROM generate_series(1,100) i));
+VACUUM fsm_check_size;
+SELECT pg_relation_size(reltoastrelid, 'main') AS toast_size,
+pg_relation_size(reltoastrelid, 'fsm') AS toast_fsm_size
+FROM pg_class WHERE relname = 'fsm_check_size';
+ toast_size | toast_fsm_size 
+------------+----------------
+       8192 |              0
+(1 row)
+
+DROP TABLE fsm_check_size;
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index cc0bbf5db9f..4051a4ad4e1 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -69,6 +69,12 @@ test: create_aggregate create_function_3 create_cast constraints triggers inheri
 test: sanity_check
 
 # ----------
+# fsm does a delete followed by vacuum, and running it in parallel can prevent
+# removal of rows.
+# ----------
+test: fsm
+
+# ----------
 # Believe it or not, select creates a table, subsequent
 # tests need.
 # ----------
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index 0c10c7100c6..ac1ea622d65 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -80,6 +80,7 @@ test: roleattributes
 test: create_am
 test: hash_func
 test: sanity_check
+test: fsm
 test: errors
 test: select
 test: select_into
diff --git a/src/test/regress/sql/fsm.sql b/src/test/regress/sql/fsm.sql
new file mode 100644
index 00000000000..07f505591a8
--- /dev/null
+++ b/src/test/regress/sql/fsm.sql
@@ -0,0 +1,55 @@
+--
+-- Free Space Map test
+--
+
+CREATE TABLE fsm_check_size (num int, str text);
+
+-- Fill 3 blocks with as many large records as will fit
+-- No FSM
+INSERT INTO fsm_check_size SELECT i, rpad('', 1024, 'a')
+FROM generate_series(1,7*3) i;
+VACUUM fsm_check_size;
+SELECT pg_relation_size('fsm_check_size', 'main') AS heap_size,
+pg_relation_size('fsm_check_size', 'fsm') AS fsm_size;
+
+-- Clear some space on block 0
+DELETE FROM fsm_check_size WHERE num <= 5;
+VACUUM fsm_check_size;
+
+-- Insert small record in block 2 to set the cached smgr targetBlock
+INSERT INTO fsm_check_size VALUES(99, 'b');
+
+-- Insert large record and make sure it goes in block 0 rather than
+-- causing the relation to extend
+INSERT INTO fsm_check_size VALUES (101, rpad('', 1024, 'a'));
+SELECT pg_relation_size('fsm_check_size', 'main') AS heap_size,
+pg_relation_size('fsm_check_size', 'fsm') AS fsm_size;
+
+-- Extend table with enough blocks to exceed the FSM threshold
+-- FSM is created and extended to 3 blocks
+INSERT INTO fsm_check_size SELECT i, 'c' FROM generate_series(200,1200) i;
+VACUUM fsm_check_size;
+SELECT pg_relation_size('fsm_check_size', 'fsm') AS fsm_size;
+
+-- Truncate heap to 1 block
+-- No change in FSM
+DELETE FROM fsm_check_size WHERE num > 7;
+VACUUM fsm_check_size;
+SELECT pg_relation_size('fsm_check_size', 'fsm') AS fsm_size;
+
+-- Truncate heap to 0 blocks
+-- FSM now truncated to 2 blocks
+DELETE FROM fsm_check_size;
+VACUUM fsm_check_size;
+SELECT pg_relation_size('fsm_check_size', 'fsm') AS fsm_size;
+
+-- Add long random string to extend TOAST table to 1 block
+INSERT INTO fsm_check_size
+VALUES(0, (SELECT string_agg(md5(chr(i)), '')
+		   FROM generate_series(1,100) i));
+VACUUM fsm_check_size;
+SELECT pg_relation_size(reltoastrelid, 'main') AS toast_size,
+pg_relation_size(reltoastrelid, 'fsm') AS toast_fsm_size
+FROM pg_class WHERE relname = 'fsm_check_size';
+
+DROP TABLE fsm_check_size;