From 7862e173741dee7172b380c23a24a07cfade41ef Mon Sep 17 00:00:00 2001 From: Jeff Davis Date: Wed, 18 Mar 2026 11:52:15 -0700 Subject: [PATCH v2] Fix dependency on FDW handler. ALTER FOREIGN DATA WRAPPER could drop the dependency on the handler function if it wasn't explicitly specified. Reviewed-by: Nathan Bossart Discussion: https://postgr.es/m/35c44a4b7fb76d35418c4d66b775a88f4ce60c86.camel@j-davis.com Backpatch-through: 14 --- src/backend/commands/foreigncmds.c | 5 +++++ src/test/regress/expected/foreign_data.out | 7 +++++++ src/test/regress/sql/foreign_data.sql | 5 +++++ 3 files changed, 17 insertions(+) diff --git a/src/backend/commands/foreigncmds.c b/src/backend/commands/foreigncmds.c index 45681235782..0b31afd8a79 100644 --- a/src/backend/commands/foreigncmds.c +++ b/src/backend/commands/foreigncmds.c @@ -786,6 +786,11 @@ AlterForeignDataWrapper(ParseState *pstate, AlterFdwStmt *stmt) ereport(WARNING, (errmsg("changing the foreign-data wrapper handler can change behavior of existing foreign tables"))); } + else + { + /* handler unchanged */ + fdwhandler = fdwForm->fdwhandler; + } if (validator_given) { diff --git a/src/test/regress/expected/foreign_data.out b/src/test/regress/expected/foreign_data.out index 6af54d9803f..35d75180dff 100644 --- a/src/test/regress/expected/foreign_data.out +++ b/src/test/regress/expected/foreign_data.out @@ -106,6 +106,13 @@ ERROR: conflicting or redundant options LINE 1: ...GN DATA WRAPPER test_fdw HANDLER test_fdw_handler HANDLER in... ^ CREATE FOREIGN DATA WRAPPER test_fdw HANDLER test_fdw_handler; +-- should preserve dependency on test_fdw_handler +ALTER FOREIGN DATA WRAPPER test_fdw VALIDATOR postgresql_fdw_validator; +WARNING: changing the foreign-data wrapper validator can cause the options for dependent objects to become invalid +DROP FUNCTION test_fdw_handler(); -- ERROR +ERROR: cannot drop function test_fdw_handler() because other objects depend on it +DETAIL: foreign-data wrapper test_fdw depends on function test_fdw_handler() +HINT: Use DROP ... CASCADE to drop the dependent objects too. DROP FOREIGN DATA WRAPPER test_fdw; -- ALTER FOREIGN DATA WRAPPER ALTER FOREIGN DATA WRAPPER foo OPTIONS (nonexistent 'fdw'); -- ERROR diff --git a/src/test/regress/sql/foreign_data.sql b/src/test/regress/sql/foreign_data.sql index 084d5559e09..0080bfb8856 100644 --- a/src/test/regress/sql/foreign_data.sql +++ b/src/test/regress/sql/foreign_data.sql @@ -67,6 +67,11 @@ CREATE FUNCTION invalid_fdw_handler() RETURNS int LANGUAGE SQL AS 'SELECT 1;'; CREATE FOREIGN DATA WRAPPER test_fdw HANDLER invalid_fdw_handler; -- ERROR CREATE FOREIGN DATA WRAPPER test_fdw HANDLER test_fdw_handler HANDLER invalid_fdw_handler; -- ERROR CREATE FOREIGN DATA WRAPPER test_fdw HANDLER test_fdw_handler; + +-- should preserve dependency on test_fdw_handler +ALTER FOREIGN DATA WRAPPER test_fdw VALIDATOR postgresql_fdw_validator; +DROP FUNCTION test_fdw_handler(); -- ERROR + DROP FOREIGN DATA WRAPPER test_fdw; -- ALTER FOREIGN DATA WRAPPER -- 2.43.0