Fix race condition in parallel regression tests. The new plancache test

was expecting there to be no regular table named 'foo', but it turns out
the rules test transiently creates one, so that plancache would sometimes
fail.  I couldn't reproduce that in quite a few tries here, but several
buildfarm machines have shown the failure.  Fix by renaming plancache's
temp table to something nonconflicting.

src/test/regress/expected/plancache.out

 --
 -- Tests to exercise the plan caching/invalidation mechanism
 --
-CREATE TEMP TABLE foo AS SELECT * FROM int8_tbl;
+CREATE TEMP TABLE pcachetest AS SELECT * FROM int8_tbl;
 -- create and use a cached plan
-PREPARE prepstmt AS SELECT * FROM foo;
+PREPARE prepstmt AS SELECT * FROM pcachetest;
 EXECUTE prepstmt;
         q1        |        q2         
 ------------------+-------------------
@@ -15,7 +15,7 @@ EXECUTE prepstmt;
 (5 rows)
 
 -- and one with parameters
-PREPARE prepstmt2(bigint) AS SELECT * FROM foo WHERE q1 = $1;
+PREPARE prepstmt2(bigint) AS SELECT * FROM pcachetest WHERE q1 = $1;
 EXECUTE prepstmt2(123);
  q1  |        q2        
 -----+------------------
@@ -24,14 +24,14 @@ EXECUTE prepstmt2(123);
 (2 rows)
 
 -- invalidate the plans and see what happens
-DROP TABLE foo;
+DROP TABLE pcachetest;
 EXECUTE prepstmt;
-ERROR:  relation "foo" does not exist
+ERROR:  relation "pcachetest" does not exist
 EXECUTE prepstmt2(123);
-ERROR:  relation "foo" does not exist
+ERROR:  relation "pcachetest" does not exist
 -- recreate the temp table (this demonstrates that the raw plan is
 -- purely textual and doesn't depend on OIDs, for instance)
-CREATE TEMP TABLE foo AS SELECT * FROM int8_tbl ORDER BY 2;
+CREATE TEMP TABLE pcachetest AS SELECT * FROM int8_tbl ORDER BY 2;
 EXECUTE prepstmt;
         q1        |        q2         
 ------------------+-------------------
@@ -51,13 +51,13 @@ EXECUTE prepstmt2(123);
 
 -- prepared statements should prevent change in output tupdesc,
 -- since clients probably aren't expecting that to change on the fly
-ALTER TABLE foo ADD COLUMN q3 bigint;
+ALTER TABLE pcachetest ADD COLUMN q3 bigint;
 EXECUTE prepstmt;
 ERROR:  cached plan must not change result type
 EXECUTE prepstmt2(123);
 ERROR:  cached plan must not change result type
 -- but we're nice guys and will let you undo your mistake
-ALTER TABLE foo DROP COLUMN q3;
+ALTER TABLE pcachetest DROP COLUMN q3;
 EXECUTE prepstmt;
         q1        |        q2         
 ------------------+-------------------
@@ -77,8 +77,9 @@ EXECUTE prepstmt2(123);
 
 -- Try it with a view, which isn't directly used in the resulting plan
 -- but should trigger invalidation anyway
-CREATE TEMP VIEW voo AS SELECT * FROM foo;
-PREPARE vprep AS SELECT * FROM voo;
+CREATE TEMP VIEW pcacheview AS
+  SELECT * FROM pcachetest;
+PREPARE vprep AS SELECT * FROM pcacheview;
 EXECUTE vprep;
         q1        |        q2         
 ------------------+-------------------
@@ -89,7 +90,8 @@ EXECUTE vprep;
  4567890123456789 |  4567890123456789
 (5 rows)
 
-CREATE OR REPLACE TEMP VIEW voo AS SELECT q1, q2/2 AS q2 FROM foo;
+CREATE OR REPLACE TEMP VIEW pcacheview AS
+  SELECT q1, q2/2 AS q2 FROM pcachetest;
 EXECUTE vprep;
         q1        |        q2         
 ------------------+-------------------

src/test/regress/sql/plancache.sql

@@ -2,53 +2,55 @@
 -- Tests to exercise the plan caching/invalidation mechanism
 --
 
-CREATE TEMP TABLE foo AS SELECT * FROM int8_tbl;
+CREATE TEMP TABLE pcachetest AS SELECT * FROM int8_tbl;
 
 -- create and use a cached plan
-PREPARE prepstmt AS SELECT * FROM foo;
+PREPARE prepstmt AS SELECT * FROM pcachetest;
 
 EXECUTE prepstmt;
 
 -- and one with parameters
-PREPARE prepstmt2(bigint) AS SELECT * FROM foo WHERE q1 = $1;
+PREPARE prepstmt2(bigint) AS SELECT * FROM pcachetest WHERE q1 = $1;
 
 EXECUTE prepstmt2(123);
 
 -- invalidate the plans and see what happens
-DROP TABLE foo;
+DROP TABLE pcachetest;
 
 EXECUTE prepstmt;
 EXECUTE prepstmt2(123);
 
 -- recreate the temp table (this demonstrates that the raw plan is
 -- purely textual and doesn't depend on OIDs, for instance)
-CREATE TEMP TABLE foo AS SELECT * FROM int8_tbl ORDER BY 2;
+CREATE TEMP TABLE pcachetest AS SELECT * FROM int8_tbl ORDER BY 2;
 
 EXECUTE prepstmt;
 EXECUTE prepstmt2(123);
 
 -- prepared statements should prevent change in output tupdesc,
 -- since clients probably aren't expecting that to change on the fly
-ALTER TABLE foo ADD COLUMN q3 bigint;
+ALTER TABLE pcachetest ADD COLUMN q3 bigint;
 
 EXECUTE prepstmt;
 EXECUTE prepstmt2(123);
 
 -- but we're nice guys and will let you undo your mistake
-ALTER TABLE foo DROP COLUMN q3;
+ALTER TABLE pcachetest DROP COLUMN q3;
 
 EXECUTE prepstmt;
 EXECUTE prepstmt2(123);
 
 -- Try it with a view, which isn't directly used in the resulting plan
 -- but should trigger invalidation anyway
-CREATE TEMP VIEW voo AS SELECT * FROM foo;
+CREATE TEMP VIEW pcacheview AS
+  SELECT * FROM pcachetest;
 
-PREPARE vprep AS SELECT * FROM voo;
+PREPARE vprep AS SELECT * FROM pcacheview;
 
 EXECUTE vprep;
 
-CREATE OR REPLACE TEMP VIEW voo AS SELECT q1, q2/2 AS q2 FROM foo;
+CREATE OR REPLACE TEMP VIEW pcacheview AS
+  SELECT q1, q2/2 AS q2 FROM pcachetest;
 
 EXECUTE vprep;