From: Milen Kulev <makulev@gmx.net>
To: 'Shoaib Mir' <shoaibmir@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Pipelined functions in Postgres
Date: Tue, 19 Sep 2006 23:22:15 +0200
Message-ID: <007b01c6dc31$ae395920$0a00a8c0@trivadis.com> (raw)
In-Reply-To: <bf54be870609191405l5abc171cuc805c43bba0b0c42@mail.gmail.com>
Hello Shoaib,
I know the SETOF funcitons. I want to simulate (somehow) producer/consumer relationship with SETOF(pipelined)
functions. The first (producer )function generates records (just like your test_pipe function), and the second
function consumers the records , produced by the first function. The second function can be rows/records producer for
another consumer functions e.g. it should looks like(or similar)
select * from consumer_function( producer_function(param1, param2, ...));
What I want to achieve is to impelement some ETL logic in consumer_functions (they could be chained, of course).
The main idea is to read source DWH tables once (in producer_function, for example), and to process the rowsets
in the consumer functions. I want to avoid writing to intermediate tables while performing ETL processing .
Is this possible with SETOF functions ?
Best Regards
Milen
-----Original Message-----
From: pgsql-performance-owner@postgresql.org [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Shoaib Mir
Sent: Tuesday, September 19, 2006 11:05 PM
To: Milen Kulev
Cc: pgsql-performance@postgresql.org
Subject: Re: [PERFORM] Pipelined functions in Postgres
I think pipelined functions are code you can pretend is a database table.
For example you can do it like this in Oracle:
select * from PLSQL_FUNCTION;
You can achieve something similar in PostgreSQL using RETURN SETOF functions like this:
CREATE OR REPLACE FUNCTION test_pipe (int)
RETURNS SETOF RECORD AS
$$
DECLARE
v_rec RECORD;
BEGIN
FOR temp_rec IN (SELECT col FROM table where col > 10)
LOOP
RETURN NEXT v_rec;
END LOOP;
RETURN;
END;
$$ LANGUAGE plpgsql;
This function can be called like this:
SELECT * FROM test_pipe(10) AS tbl (col int);
Hope this helps...
Thanks,
--
Shoaib Mir
EnterpriseDB (www.enterprisedb.com)
On 9/20/06, Milen Kulev <makulev@gmx.net> wrote:
Hello Lister,
I am curios whether I can emulate the Oracle pipelined functions functionality in PG too (using RETURN NEXT ). For more
information and examples about Oracle pipelined functions see:
http://asktom.oracle.com/pls/ask/f?p=4950:8:8127757633768425921::NO::F4950_P8_DISPLAYID,F4950_P8_CRI...
I have used pipeline functions in DWH enviromnent with success and would like
To use similar concept in PG too.
Any help, examples , links and shared experiences would be greately appreciated.
Best Regards.
Milen
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To: pgsql-performance@postgresql.org
Cc: makulev@gmx.net, shoaibmir@gmail.com
Subject: Re: Pipelined functions in Postgres
In-Reply-To: <007b01c6dc31$ae395920$0a00a8c0@trivadis.com>
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