Implement function-local GUC parameter settings, as per recent discussion.

There are still some loose ends: I didn't do anything about the SET FROM
CURRENT idea yet, and it's not real clear whether we are happy with the
interaction of SET LOCAL with function-local settings.  The documentation
is a bit spartan, too.

2 files changed, 58 insertions, 0 deletions

diff --git a/src/test/regress/expected/guc.out b/src/test/regress/expected/guc.out
index d8ad5667ab7..2276cff4e0c 100644
--- a/src/test/regress/expected/guc.out
+++ b/src/test/regress/expected/guc.out
@@ -525,3 +525,36 @@ SELECT current_user = 'temp_reset_user';
 (1 row)
 
 DROP ROLE temp_reset_user;
+--
+-- Tests for function-local GUC settings
+--
+set regex_flavor = advanced;
+create function report_guc(text) returns text as
+$$ select current_setting($1) $$ language sql
+set regex_flavor = basic;
+select report_guc('regex_flavor'), current_setting('regex_flavor');
+ report_guc | current_setting 
+------------+-----------------
+ basic      | advanced
+(1 row)
+
+-- this should draw only a warning
+alter function report_guc(text) set search_path = no_such_schema;
+NOTICE:  schema "no_such_schema" does not exist
+-- with error occurring here
+select report_guc('regex_flavor'), current_setting('regex_flavor');
+ERROR:  schema "no_such_schema" does not exist
+alter function report_guc(text) reset search_path set regex_flavor = extended;
+select report_guc('regex_flavor'), current_setting('regex_flavor');
+ report_guc | current_setting 
+------------+-----------------
+ extended   | advanced
+(1 row)
+
+alter function report_guc(text) reset all;
+select report_guc('regex_flavor'), current_setting('regex_flavor');
+ report_guc | current_setting 
+------------+-----------------
+ advanced   | advanced
+(1 row)
+
diff --git a/src/test/regress/sql/guc.sql b/src/test/regress/sql/guc.sql
index a25a13820d7..ffaddec7e98 100644
--- a/src/test/regress/sql/guc.sql
+++ b/src/test/regress/sql/guc.sql
@@ -162,3 +162,28 @@ SELECT relname from pg_class where relname = 'tmp_foo';
 SELECT current_user = 'temp_reset_user';
 DROP ROLE temp_reset_user;
 
+--
+-- Tests for function-local GUC settings
+--
+
+set regex_flavor = advanced;
+
+create function report_guc(text) returns text as
+$$ select current_setting($1) $$ language sql
+set regex_flavor = basic;
+
+select report_guc('regex_flavor'), current_setting('regex_flavor');
+
+-- this should draw only a warning
+alter function report_guc(text) set search_path = no_such_schema;
+
+-- with error occurring here
+select report_guc('regex_flavor'), current_setting('regex_flavor');
+
+alter function report_guc(text) reset search_path set regex_flavor = extended;
+
+select report_guc('regex_flavor'), current_setting('regex_flavor');
+
+alter function report_guc(text) reset all;
+
+select report_guc('regex_flavor'), current_setting('regex_flavor');