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postgres_fdw: Use psql variables for connection parameters

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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 <corey.huinker@gmail.com>
Discussion: https://postgr.es/m/CADkLM=cpUiJ3QF7aUthTvaVMmgQcm7QqZBRMDLhBRTR+gJX-Og@mail.gmail.com
master
Michael Paquier 2 weeks ago
parent 317c117d6d
commit 36aed19fd9
2 changed files with 25 additions and 61 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 42
      contrib/postgres_fdw/expected/postgres_fdw.out
  2. 44
      contrib/postgres_fdw/sql/postgres_fdw.sql

42
contrib/postgres_fdw/expected/postgres_fdw.out
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@ -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;

44
contrib/postgres_fdw/sql/postgres_fdw.sql
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@ -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;

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