Improve regression test coverage for TID scanning.

TidScan plan nodes were not systematically tested before.  These additions
raise the LOC coverage number for the basic regression tests from 52% to
92% in nodeTidscan.c, and from 60% to 93% in tidpath.c.

Andres Freund, tweaked a bit by me

Discussion: https://postgr.es/m/20170320062511.hp5qeurtxrwsvfxr@alap3.anarazel.de

src/test/regress/expected/tidscan.out

@@ -0,0 +1,179 @@
+-- tests for tidscans
+CREATE TABLE tidscan(id integer);
+-- only insert a few rows, we don't want to spill onto a second table page
+INSERT INTO tidscan VALUES (1), (2), (3);
+-- show ctids
+SELECT ctid, * FROM tidscan;
+ ctid  | id 
+-------+----
+ (0,1) |  1
+ (0,2) |  2
+ (0,3) |  3
+(3 rows)
+
+-- ctid equality - implemented as tidscan
+EXPLAIN (COSTS OFF)
+SELECT ctid, * FROM tidscan WHERE ctid = '(0,1)';
+            QUERY PLAN             
+-----------------------------------
+ Tid Scan on tidscan
+   TID Cond: (ctid = '(0,1)'::tid)
+(2 rows)
+
+SELECT ctid, * FROM tidscan WHERE ctid = '(0,1)';
+ ctid  | id 
+-------+----
+ (0,1) |  1
+(1 row)
+
+EXPLAIN (COSTS OFF)
+SELECT ctid, * FROM tidscan WHERE '(0,1)' = ctid;
+            QUERY PLAN             
+-----------------------------------
+ Tid Scan on tidscan
+   TID Cond: ('(0,1)'::tid = ctid)
+(2 rows)
+
+SELECT ctid, * FROM tidscan WHERE '(0,1)' = ctid;
+ ctid  | id 
+-------+----
+ (0,1) |  1
+(1 row)
+
+-- ctid = ScalarArrayOp - implemented as tidscan
+EXPLAIN (COSTS OFF)
+SELECT ctid, * FROM tidscan WHERE ctid = ANY(ARRAY['(0,1)', '(0,2)']::tid[]);
+                      QUERY PLAN                       
+-------------------------------------------------------
+ Tid Scan on tidscan
+   TID Cond: (ctid = ANY ('{"(0,1)","(0,2)"}'::tid[]))
+(2 rows)
+
+SELECT ctid, * FROM tidscan WHERE ctid = ANY(ARRAY['(0,1)', '(0,2)']::tid[]);
+ ctid  | id 
+-------+----
+ (0,1) |  1
+ (0,2) |  2
+(2 rows)
+
+-- ctid != ScalarArrayOp - can't be implemented as tidscan
+EXPLAIN (COSTS OFF)
+SELECT ctid, * FROM tidscan WHERE ctid != ANY(ARRAY['(0,1)', '(0,2)']::tid[]);
+                      QUERY PLAN                      
+------------------------------------------------------
+ Seq Scan on tidscan
+   Filter: (ctid <> ANY ('{"(0,1)","(0,2)"}'::tid[]))
+(2 rows)
+
+SELECT ctid, * FROM tidscan WHERE ctid != ANY(ARRAY['(0,1)', '(0,2)']::tid[]);
+ ctid  | id 
+-------+----
+ (0,1) |  1
+ (0,2) |  2
+ (0,3) |  3
+(3 rows)
+
+-- tid equality extracted from sub-AND clauses
+EXPLAIN (COSTS OFF)
+SELECT ctid, * FROM tidscan
+WHERE (id = 3 AND ctid IN ('(0,2)', '(0,3)')) OR (ctid = '(0,1)' AND id = 1);
+                                                  QUERY PLAN                                                  
+--------------------------------------------------------------------------------------------------------------
+ Tid Scan on tidscan
+   TID Cond: ((ctid = ANY ('{"(0,2)","(0,3)"}'::tid[])) OR (ctid = '(0,1)'::tid))
+   Filter: (((id = 3) AND (ctid = ANY ('{"(0,2)","(0,3)"}'::tid[]))) OR ((ctid = '(0,1)'::tid) AND (id = 1)))
+(3 rows)
+
+SELECT ctid, * FROM tidscan
+WHERE (id = 3 AND ctid IN ('(0,2)', '(0,3)')) OR (ctid = '(0,1)' AND id = 1);
+ ctid  | id 
+-------+----
+ (0,1) |  1
+ (0,3) |  3
+(2 rows)
+
+-- exercise backward scan and rewind
+BEGIN;
+DECLARE c CURSOR FOR
+SELECT ctid, * FROM tidscan WHERE ctid = ANY(ARRAY['(0,1)', '(0,2)']::tid[]);
+FETCH ALL FROM c;
+ ctid  | id 
+-------+----
+ (0,1) |  1
+ (0,2) |  2
+(2 rows)
+
+FETCH BACKWARD 1 FROM c;
+ ctid  | id 
+-------+----
+ (0,2) |  2
+(1 row)
+
+FETCH FIRST FROM c;
+ ctid  | id 
+-------+----
+ (0,1) |  1
+(1 row)
+
+ROLLBACK;
+-- tidscan via CURRENT OF
+BEGIN;
+DECLARE c CURSOR FOR SELECT ctid, * FROM tidscan;
+FETCH NEXT FROM c; -- skip one row
+ ctid  | id 
+-------+----
+ (0,1) |  1
+(1 row)
+
+FETCH NEXT FROM c;
+ ctid  | id 
+-------+----
+ (0,2) |  2
+(1 row)
+
+-- perform update
+EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
+UPDATE tidscan SET id = -id WHERE CURRENT OF c RETURNING *;
+                    QUERY PLAN                     
+---------------------------------------------------
+ Update on tidscan (actual rows=1 loops=1)
+   ->  Tid Scan on tidscan (actual rows=1 loops=1)
+         TID Cond: CURRENT OF c
+(3 rows)
+
+FETCH NEXT FROM c;
+ ctid  | id 
+-------+----
+ (0,3) |  3
+(1 row)
+
+-- perform update
+EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
+UPDATE tidscan SET id = -id WHERE CURRENT OF c RETURNING *;
+                    QUERY PLAN                     
+---------------------------------------------------
+ Update on tidscan (actual rows=1 loops=1)
+   ->  Tid Scan on tidscan (actual rows=1 loops=1)
+         TID Cond: CURRENT OF c
+(3 rows)
+
+SELECT * FROM tidscan;
+ id 
+----
+  1
+ -2
+ -3
+(3 rows)
+
+-- position cursor past any rows
+FETCH NEXT FROM c;
+ ctid | id 
+------+----
+(0 rows)
+
+-- should error out
+EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
+UPDATE tidscan SET id = -id WHERE CURRENT OF c RETURNING *;
+ERROR:  cursor "c" is not positioned on a row
+ROLLBACK;
+DROP TABLE tidscan;

src/test/regress/parallel_schedule

@@ -89,7 +89,7 @@ test: brin gin gist spgist privileges init_privs security_label collate matview
 # ----------
 # Another group of parallel tests
 # ----------
-test: alter_generic alter_operator misc psql async dbsize misc_functions sysviews tsrf
+test: alter_generic alter_operator misc psql async dbsize misc_functions sysviews tsrf tidscan
 
 # rules cannot run concurrently with any test that creates a view
 test: rules psql_crosstab amutils

src/test/regress/serial_schedule

@@ -129,6 +129,7 @@ test: dbsize
 test: misc_functions
 test: sysviews
 test: tsrf
+test: tidscan
 test: rules
 test: psql_crosstab
 test: select_parallel

src/test/regress/sql/tidscan.sql

@@ -0,0 +1,66 @@
+-- tests for tidscans
+
+CREATE TABLE tidscan(id integer);
+
+-- only insert a few rows, we don't want to spill onto a second table page
+INSERT INTO tidscan VALUES (1), (2), (3);
+
+-- show ctids
+SELECT ctid, * FROM tidscan;
+
+-- ctid equality - implemented as tidscan
+EXPLAIN (COSTS OFF)
+SELECT ctid, * FROM tidscan WHERE ctid = '(0,1)';
+SELECT ctid, * FROM tidscan WHERE ctid = '(0,1)';
+
+EXPLAIN (COSTS OFF)
+SELECT ctid, * FROM tidscan WHERE '(0,1)' = ctid;
+SELECT ctid, * FROM tidscan WHERE '(0,1)' = ctid;
+
+-- ctid = ScalarArrayOp - implemented as tidscan
+EXPLAIN (COSTS OFF)
+SELECT ctid, * FROM tidscan WHERE ctid = ANY(ARRAY['(0,1)', '(0,2)']::tid[]);
+SELECT ctid, * FROM tidscan WHERE ctid = ANY(ARRAY['(0,1)', '(0,2)']::tid[]);
+
+-- ctid != ScalarArrayOp - can't be implemented as tidscan
+EXPLAIN (COSTS OFF)
+SELECT ctid, * FROM tidscan WHERE ctid != ANY(ARRAY['(0,1)', '(0,2)']::tid[]);
+SELECT ctid, * FROM tidscan WHERE ctid != ANY(ARRAY['(0,1)', '(0,2)']::tid[]);
+
+-- tid equality extracted from sub-AND clauses
+EXPLAIN (COSTS OFF)
+SELECT ctid, * FROM tidscan
+WHERE (id = 3 AND ctid IN ('(0,2)', '(0,3)')) OR (ctid = '(0,1)' AND id = 1);
+SELECT ctid, * FROM tidscan
+WHERE (id = 3 AND ctid IN ('(0,2)', '(0,3)')) OR (ctid = '(0,1)' AND id = 1);
+
+-- exercise backward scan and rewind
+BEGIN;
+DECLARE c CURSOR FOR
+SELECT ctid, * FROM tidscan WHERE ctid = ANY(ARRAY['(0,1)', '(0,2)']::tid[]);
+FETCH ALL FROM c;
+FETCH BACKWARD 1 FROM c;
+FETCH FIRST FROM c;
+ROLLBACK;
+
+-- tidscan via CURRENT OF
+BEGIN;
+DECLARE c CURSOR FOR SELECT ctid, * FROM tidscan;
+FETCH NEXT FROM c; -- skip one row
+FETCH NEXT FROM c;
+-- perform update
+EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
+UPDATE tidscan SET id = -id WHERE CURRENT OF c RETURNING *;
+FETCH NEXT FROM c;
+-- perform update
+EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
+UPDATE tidscan SET id = -id WHERE CURRENT OF c RETURNING *;
+SELECT * FROM tidscan;
+-- position cursor past any rows
+FETCH NEXT FROM c;
+-- should error out
+EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
+UPDATE tidscan SET id = -id WHERE CURRENT OF c RETURNING *;
+ROLLBACK;
+
+DROP TABLE tidscan;