From 36aed19fd99021ad9f727e4fd4bceb086a7cf54d Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Mon, 1 Sep 2025 09:02:03 +0900 Subject: [PATCH] postgres_fdw: Use psql variables for connection parameters Several statements need to reference the current connection's current database name and current port value. Until now, this has been accomplished by creating dynamic SQL statements inside of a DO block, which is not as easy to parse. It also takes away some of the granularity of any error messages that might occur, making debugging harder. By capturing the connection-specific settings into psql variables, it becomes possible to write simpler SQL statements for the FDW objects. This eliminates most of DO blocks used in this test, making it a bit more readable and shorter. Author: Author: Corey Huinker Discussion: https://postgr.es/m/CADkLM=cpUiJ3QF7aUthTvaVMmgQcm7QqZBRMDLhBRTR+gJX-Og@mail.gmail.com --- .../postgres_fdw/expected/postgres_fdw.out | 42 +++++------------- contrib/postgres_fdw/sql/postgres_fdw.sql | 44 ++++++------------- 2 files changed, 25 insertions(+), 61 deletions(-) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index d3323b04676c..78b8367d2893 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -2,23 +2,16 @@ -- create FDW objects -- =================================================================== CREATE EXTENSION postgres_fdw; +SELECT current_database() AS current_database, + current_setting('port') AS current_port +\gset CREATE SERVER testserver1 FOREIGN DATA WRAPPER postgres_fdw; -DO $d$ - BEGIN - EXECUTE $$CREATE SERVER loopback FOREIGN DATA WRAPPER postgres_fdw - OPTIONS (dbname '$$||current_database()||$$', - port '$$||current_setting('port')||$$' - )$$; - EXECUTE $$CREATE SERVER loopback2 FOREIGN DATA WRAPPER postgres_fdw - OPTIONS (dbname '$$||current_database()||$$', - port '$$||current_setting('port')||$$' - )$$; - EXECUTE $$CREATE SERVER loopback3 FOREIGN DATA WRAPPER postgres_fdw - OPTIONS (dbname '$$||current_database()||$$', - port '$$||current_setting('port')||$$' - )$$; - END; -$d$; +CREATE SERVER loopback FOREIGN DATA WRAPPER postgres_fdw + OPTIONS (dbname :'current_database', port :'current_port'); +CREATE SERVER loopback2 FOREIGN DATA WRAPPER postgres_fdw + OPTIONS (dbname :'current_database', port :'current_port'); +CREATE SERVER loopback3 FOREIGN DATA WRAPPER postgres_fdw + OPTIONS (dbname :'current_database', port :'current_port'); CREATE USER MAPPING FOR public SERVER testserver1 OPTIONS (user 'value', password 'value'); CREATE USER MAPPING FOR CURRENT_USER SERVER loopback; @@ -235,12 +228,7 @@ SELECT c3, c4 FROM ft1 ORDER BY c3, c1 LIMIT 1; -- should work ALTER SERVER loopback OPTIONS (SET dbname 'no such database'); SELECT c3, c4 FROM ft1 ORDER BY c3, c1 LIMIT 1; -- should fail ERROR: could not connect to server "loopback" -DO $d$ - BEGIN - EXECUTE $$ALTER SERVER loopback - OPTIONS (SET dbname '$$||current_database()||$$')$$; - END; -$d$; +ALTER SERVER loopback OPTIONS (SET dbname :'current_database'); SELECT c3, c4 FROM ft1 ORDER BY c3, c1 LIMIT 1; -- should work again c3 | c4 -------+------------------------------ @@ -10643,14 +10631,8 @@ SHOW is_superuser; (1 row) -- This will be OK, we can create the FDW -DO $d$ - BEGIN - EXECUTE $$CREATE SERVER loopback_nopw FOREIGN DATA WRAPPER postgres_fdw - OPTIONS (dbname '$$||current_database()||$$', - port '$$||current_setting('port')||$$' - )$$; - END; -$d$; +CREATE SERVER loopback_nopw FOREIGN DATA WRAPPER postgres_fdw + OPTIONS (dbname :'current_database', port :'current_port'); -- But creation of user mappings for non-superusers should fail CREATE USER MAPPING FOR public SERVER loopback_nopw; CREATE USER MAPPING FOR CURRENT_USER SERVER loopback_nopw; diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index 2c609e060b7c..3b7da1285192 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -4,24 +4,17 @@ CREATE EXTENSION postgres_fdw; -CREATE SERVER testserver1 FOREIGN DATA WRAPPER postgres_fdw; -DO $d$ - BEGIN - EXECUTE $$CREATE SERVER loopback FOREIGN DATA WRAPPER postgres_fdw - OPTIONS (dbname '$$||current_database()||$$', - port '$$||current_setting('port')||$$' - )$$; - EXECUTE $$CREATE SERVER loopback2 FOREIGN DATA WRAPPER postgres_fdw - OPTIONS (dbname '$$||current_database()||$$', - port '$$||current_setting('port')||$$' - )$$; - EXECUTE $$CREATE SERVER loopback3 FOREIGN DATA WRAPPER postgres_fdw - OPTIONS (dbname '$$||current_database()||$$', - port '$$||current_setting('port')||$$' - )$$; - END; -$d$; +SELECT current_database() AS current_database, + current_setting('port') AS current_port +\gset +CREATE SERVER testserver1 FOREIGN DATA WRAPPER postgres_fdw; +CREATE SERVER loopback FOREIGN DATA WRAPPER postgres_fdw + OPTIONS (dbname :'current_database', port :'current_port'); +CREATE SERVER loopback2 FOREIGN DATA WRAPPER postgres_fdw + OPTIONS (dbname :'current_database', port :'current_port'); +CREATE SERVER loopback3 FOREIGN DATA WRAPPER postgres_fdw + OPTIONS (dbname :'current_database', port :'current_port'); CREATE USER MAPPING FOR public SERVER testserver1 OPTIONS (user 'value', password 'value'); CREATE USER MAPPING FOR CURRENT_USER SERVER loopback; @@ -233,12 +226,7 @@ ALTER FOREIGN TABLE ft2 ALTER COLUMN c1 OPTIONS (column_name 'C 1'); SELECT c3, c4 FROM ft1 ORDER BY c3, c1 LIMIT 1; -- should work ALTER SERVER loopback OPTIONS (SET dbname 'no such database'); SELECT c3, c4 FROM ft1 ORDER BY c3, c1 LIMIT 1; -- should fail -DO $d$ - BEGIN - EXECUTE $$ALTER SERVER loopback - OPTIONS (SET dbname '$$||current_database()||$$')$$; - END; -$d$; +ALTER SERVER loopback OPTIONS (SET dbname :'current_database'); SELECT c3, c4 FROM ft1 ORDER BY c3, c1 LIMIT 1; -- should work again -- Test that alteration of user mapping options causes reconnection @@ -3375,14 +3363,8 @@ SET ROLE regress_nosuper; SHOW is_superuser; -- This will be OK, we can create the FDW -DO $d$ - BEGIN - EXECUTE $$CREATE SERVER loopback_nopw FOREIGN DATA WRAPPER postgres_fdw - OPTIONS (dbname '$$||current_database()||$$', - port '$$||current_setting('port')||$$' - )$$; - END; -$d$; +CREATE SERVER loopback_nopw FOREIGN DATA WRAPPER postgres_fdw + OPTIONS (dbname :'current_database', port :'current_port'); -- But creation of user mappings for non-superusers should fail CREATE USER MAPPING FOR public SERVER loopback_nopw;