Fix support for CREATE TABLE IF NOT EXISTS AS EXECUTE

The grammar IF NOT EXISTS for CTAS is supported since 9.5 and documented
as such, however the case of using EXECUTE as query has never been
covered as EXECUTE CTAS statements and normal CTAS statements are parsed
separately.

Author: Andreas Karlsson
Discussion: https://postgr.es/m/2ddcc188-e37c-a0be-32bf-a56b07c3559e@proxel.se
Backpatch-through: 9.5

2 files changed, 22 insertions, 0 deletions

diff --git a/src/test/regress/expected/create_table.out b/src/test/regress/expected/create_table.out
index 41ceb874e8f..145bac1b2f2 100644
--- a/src/test/regress/expected/create_table.out
+++ b/src/test/regress/expected/create_table.out
@@ -250,6 +250,20 @@ ERROR:  relation "as_select1" already exists
 CREATE TABLE IF NOT EXISTS as_select1 AS SELECT * FROM pg_class WHERE relkind = 'r';
 NOTICE:  relation "as_select1" already exists, skipping
 DROP TABLE as_select1;
+PREPARE select1 AS SELECT 1 as a;
+CREATE TABLE as_select1 AS EXECUTE select1;
+CREATE TABLE as_select1 AS EXECUTE select1;
+ERROR:  relation "as_select1" already exists
+SELECT * FROM as_select1;
+ a 
+---
+ 1
+(1 row)
+
+CREATE TABLE IF NOT EXISTS as_select1 AS EXECUTE select1;
+NOTICE:  relation "as_select1" already exists, skipping
+DROP TABLE as_select1;
+DEALLOCATE select1;
 -- check that the oid column is added before the primary key is checked
 CREATE TABLE oid_pk (f1 INT, PRIMARY KEY(oid)) WITH OIDS;
 DROP TABLE oid_pk;
diff --git a/src/test/regress/sql/create_table.sql b/src/test/regress/sql/create_table.sql
index 78bdc8bf5e7..ec19f9a34f8 100644
--- a/src/test/regress/sql/create_table.sql
+++ b/src/test/regress/sql/create_table.sql
@@ -266,6 +266,14 @@ CREATE TABLE as_select1 AS SELECT * FROM pg_class WHERE relkind = 'r';
 CREATE TABLE IF NOT EXISTS as_select1 AS SELECT * FROM pg_class WHERE relkind = 'r';
 DROP TABLE as_select1;
 
+PREPARE select1 AS SELECT 1 as a;
+CREATE TABLE as_select1 AS EXECUTE select1;
+CREATE TABLE as_select1 AS EXECUTE select1;
+SELECT * FROM as_select1;
+CREATE TABLE IF NOT EXISTS as_select1 AS EXECUTE select1;
+DROP TABLE as_select1;
+DEALLOCATE select1;
+
 -- check that the oid column is added before the primary key is checked
 CREATE TABLE oid_pk (f1 INT, PRIMARY KEY(oid)) WITH OIDS;
 DROP TABLE oid_pk;