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From: Glyn Astill <glynastill@yahoo.co.uk>
To: ssylla <stefansylla@gmx.de>
To: pgsql-sql@postgresql.org <pgsql-sql@postgresql.org>
Subject: Re: Trigger function - variable for schema name
Date: Mon, 27 Jan 2014 10:47:06 +0000 (GMT)
Message-ID: <1390819626.71225.YahooMailNeo@web133206.mail.ir2.yahoo.com> (raw)
In-Reply-To: <1390811996770-5788931.post@n5.nabble.com>
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> From: ssylla <stefansylla@gmx.de>

>To: pgsql-sql@postgresql.org 
>Sent: Monday, 27 January 2014, 8:39
>Subject: [SQL] Trigger function - variable for schema name
> 
>
>Dear list,
>
>I have the following trigger function an try to use TG_ARGV as a variable
>for the schema name of the table that caused the trigger:
>
>CREATE OR REPLACE FUNCTION trigger_function1()
>  RETURNS trigger AS
>$BODY$
>    declare my_schema text;
>    begin
>        my_schema := TG_ARGV[0];
>        select table2.id into new.id from my_schema.table2;
>        new.columnx=function1(my_schema,value1);
>     return new;
>end:
>$$
>language plpgsql
>CREATE TRIGGER trigger_function1
>  BEFORE INSERT
>  ON schema1.table1
>  FOR EACH ROW
>  EXECUTE PROCEDURE trigger_function1('schema1');
>
>Using the trigger I get the following message:
>ERROR: schema "my_schema" does not exist
>

To do what you're trying to do there you'd probably be best to use EXECUTE:

CREATE OR REPLACE FUNCTION trigger_function1()
  RETURNS trigger AS
$BODY$
    declare my_schema text;
    begin
        my_schema := TG_ARGV[0];
        EXECUTE 'select table2.id into new.id from ' || quote_ident(my_schema) || '.table2';
        new.columnx=function1(my_schema,value1);
    return new;
end:
$$
language plpgsql


>So far I tried another option by temporarily changing the search path, but
>that might cause problems with other users who are working on other schemas
>of the database at the same time. That's why I would like to write the
>trigger in a way that it will only perform on the specified schema, but not
>changing the global search_path of the database.
>I also tried using dynamic sql with "execute format('...', TG_TABLE_SCHEMA);
>but that will only work inside the trigger, not if I want to pass the schema
>name to another function that is called from within the trigger.


We'll I don't see why you couldn't pull the current schema with TG_TABLE_SCHEMA and pass it as a variable to your other function, but I'm not entirely sure what you're trying to do to be honest.



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