Re: [PATCH] Add pg_get_policy_ddl() function to reconstruct CREATE POLICY statement

The get_formatted_string function is needed. Instead of using multiple if statements for the pretty flag, it’s better to have a generic function. This will be useful if the pretty-format DDL implementation is accepted by the community, as it can be reused by other pg_get_<object>_ddl() DDL functions added in the future. 

in pg_get_triggerdef_worker, I found the below code pattern:
    /*
     * In non-pretty mode, always schema-qualify the target table name for
     * safety.  In pretty mode, schema-qualify only if not visible.
     */
    appendStringInfo(&buf, " ON %s ",
                     pretty ?
                     generate_relation_name(trigrec->tgrelid, NIL) :
                     generate_qualified_relation_name(trigrec->tgrelid));

maybe we can apply it too while construct query string:
"CREATE POLICY %s ON %s",

In my opinion, the table name should always be schema-qualified, which I have addressed in the v4 patch. The implementation of the pretty flag here differs from pg_get_triggerdef_worker, which is used only for the target table name. In my patch, the pretty flag adds \t and \n to each different clause (example AS, FOR, USING ...)
 

I think that's where the confusion lies with adding `pretty` to the DDL functions. The `pretty` flag set to `true` on other functions is used to "not" show the schema name. But in the case of this function, it is used to format the statement. I wonder if the word `format` or `pretty_format` is a better name? `pretty` itself in the codebase isn't a very clear name regardless.

In my opinion, we should first decide whether we want the DDL statement to be in a 'pretty' format or not. Personally, I believe it should be, since parsing a one-line DDL statement can be quite complex and difficult for users of this function. From a user’s perspective, having the entire DDL in a single line makes it harder to read and understand. The flag allows users to disable the pretty format by passing false.

--

Best, 

Phil Alger