Thanks for the valuable feedback on my previous patch.
Based on the review comments, I have updated the patch as follows:
- Limited the error trigger only to the case where the original function is IMMUTABLE but the new definition is not. - Changed the error code to ERRCODE_FEATURE_NOT_SUPPORTED for better semantics. - Improved code indentation and style to align with project conventions. - Added a regression test case in create_function_sql.sql to verify the new behavior.
The full updated patch is attached below.
Please take a look at this revised version. I look forward to your feedback and suggestions.
On Mon, Jun 30, 2025 at 5:34 PM sundayjiang(蒋浩天) <sundayjiang@tencent.com> wrote: > > The purpose of this patch is to prevent replacing a function via `CREATE OR REPLACE FUNCTION` with a new definition that is not marked as `IMMUTABLE`, if the existing function is referenced by an index expression. > > Replacing such functions may lead to index corruption or runtime semantic inconsistencies, especially when the function’s output is not stable for the same input. > > If a function is used in an index, it can only be replaced if it is declared as `IMMUTABLE`. >
looking at the right above code ``if (oldproc->prokind != prokind)``
+ if(prokind == PROKIND_FUNCTION && oldproc->provolatile == PROVOLATILE_IMMUTABLE && + volatility != PROVOLATILE_IMMUTABLE) + { curly brace generally begins with a new line.
if (index_found) + ereport(ERROR, + (errcode(ERRCODE_DEPENDENT_OBJECTS_STILL_EXIST), + errmsg("cannot replace function \"%s\" with a non-IMMUTABLE function because it is used by an index", + procedureName))); Here, errcode ERRCODE_FEATURE_NOT_SUPPORTED would be more appropriate.
you can add a simple test in src/test/regress/sql/create_function_sql.sql for example: CREATE OR REPLACE FUNCTION get_a_int(int default 2) RETURNS int IMMUTABLE AS 'select $1' LANGUAGE sql; create table t1(a int); create index on t1((get_a_int(a))); CREATE OR REPLACE FUNCTION get_a_int(int default 2) RETURNS int AS 'select $1' LANGUAGE sql;
