postgres_fdw: set search_path to 'pg_catalog' while deparsing constants.

The motivation for this is to ensure successful transmission of the
values of constants of regconfig and other reg* types.  The remote
will be reading them with search_path = 'pg_catalog', so schema
qualification is necessary when referencing objects in other schemas.

Per bug #17483 from Emmanuel Quincerot.  Back-patch to all supported
versions.  (There's some other stuff to do here, but it's less
back-patchable.)

Discussion: https://postgr.es/m/1423433.1652722406@sss.pgh.pa.us

diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index 5f2ef88cf38a212c95636706b690feeb988b4171..a6c1b162758e0c069503ffc3751bf7c76cbe7d9b 100644 (file)
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -1163,6 +1163,26 @@ SELECT * FROM ft1 WHERE CASE c3 COLLATE "C" WHEN c6 THEN true ELSE c3 < 'bar' EN
    Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1"
 (4 rows)
 
+-- check schema-qualification of regconfig constant
+CREATE TEXT SEARCH CONFIGURATION public.custom_search
+  (COPY = pg_catalog.english);
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT c1, to_tsvector('custom_search'::regconfig, c3) FROM ft1
+WHERE c1 = 642 AND length(to_tsvector('custom_search'::regconfig, c3)) > 0;
+                                                                  QUERY PLAN                                                                  
+----------------------------------------------------------------------------------------------------------------------------------------------
+ Foreign Scan on public.ft1
+   Output: c1, to_tsvector('custom_search'::regconfig, c3)
+   Remote SQL: SELECT "C 1", c3 FROM "S 1"."T 1" WHERE (("C 1" = 642)) AND ((length(to_tsvector('public.custom_search'::regconfig, c3)) > 0))
+(3 rows)
+
+SELECT c1, to_tsvector('custom_search'::regconfig, c3) FROM ft1
+WHERE c1 = 642 AND length(to_tsvector('custom_search'::regconfig, c3)) > 0;
+ c1  | to_tsvector 
+-----+-------------
+ 642 | '00642':1
+(1 row)
+
 -- ===================================================================
 -- JOIN queries
 -- ===================================================================

diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index 955a428e3dab0b1b8fc4a6b9c552460170663a28..f3b93954eeaed80df1e8aab9e02054262366fd40 100644 (file)
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -3896,6 +3896,14 @@ set_transmission_modes(void)
                                                                 PGC_USERSET, PGC_S_SESSION,
                                                                 GUC_ACTION_SAVE, true, 0, false);
 
+       /*
+        * In addition force restrictive search_path, in case there are any
+        * regproc or similar constants to be printed.
+        */
+       (void) set_config_option("search_path", "pg_catalog",
+                                                        PGC_USERSET, PGC_S_SESSION,
+                                                        GUC_ACTION_SAVE, true, 0, false);
+
        return nestlevel;
 }
 

diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index ae1fc8f58be53481fc4a963e21d50b5c0cee7714..a4f988fdb82ca4fb9b1046c5b4d65f72631066c2 100644 (file)
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -442,6 +442,15 @@ SELECT * FROM ft1 WHERE CASE c3 WHEN c6 THEN true ELSE c3 < 'bar' END;
 EXPLAIN (VERBOSE, COSTS OFF)
 SELECT * FROM ft1 WHERE CASE c3 COLLATE "C" WHEN c6 THEN true ELSE c3 < 'bar' END;
 
+-- check schema-qualification of regconfig constant
+CREATE TEXT SEARCH CONFIGURATION public.custom_search
+  (COPY = pg_catalog.english);
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT c1, to_tsvector('custom_search'::regconfig, c3) FROM ft1
+WHERE c1 = 642 AND length(to_tsvector('custom_search'::regconfig, c3)) > 0;
+SELECT c1, to_tsvector('custom_search'::regconfig, c3) FROM ft1
+WHERE c1 = 642 AND length(to_tsvector('custom_search'::regconfig, c3)) > 0;
+
 -- ===================================================================
 -- JOIN queries
 -- ===================================================================