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From: Adrian Klaver <adrian.klaver@aklaver.com>
To: RAJIN RAJ K <rajin89@gmail.com>
To: pgsql-sql@postgresql.org
To: pgsql-hackers@postgresql.org
To: pgsql-general@postgresql.org
Subject: Re: Alternate methods for multiple rows input/output to a function.
Date: Tue, 28 May 2019 07:59:30 -0700
Message-ID: <bccc8ca0-cc0b-f69e-4a6b-c3d40cae5b25@aklaver.com> (raw)
In-Reply-To: <CAC+XFJgGBkHUrypj0m=kTmQJBYBh6NcfL1qYaaSvQKw73mrijw@mail.gmail.com>
References: <CAC+XFJgGBkHUrypj0m=kTmQJBYBh6NcfL1qYaaSvQKw73mrijw@mail.gmail.com>

On 5/28/19 7:36 AM, RAJIN RAJ K wrote:
> --> Function ' filter_id ' filters the ID's based on some conditions.
> --> Input is set of ID's. (Not directly taking the input since there is 
> no provision to pass multiple rows to a function)

To be honest I cannot follow what you are trying to achieve below. I do 
have one suggestion as to creating temp tables.

Why not use a  CTE:

https://www.postgresql.org/docs/11/queries-with.html

in the function to build a 'temp' table on the fly?

> 
> create function filter_id()
> return table (id bigint)
> begin
> 
> --> Assuming input table is already created #temp_input_id
> 
> retun query as select id
> from tbl a
> inner join
> #temp_input_id b on (a.id <http://a.id; = b.id <http://b.id;)
> where a.<conditions>;
> 
> end;
> 
> 
> --> Calling Function:
> 
> create function caller()
> return table (id bigint,col1 bigint, col2 bigint)
> begin
> 
> --> do some processing
> 
> --> Find out the input id's for filtering.
> 
> --> Create temp table for providing input for the filtering function
> 
> create temp table #TEMP1
> as select id from tbla........;
> (Cannot move the input id logic to  filter_function)
> 
> --> calling the filter function
> create temp table #TEMP2
> as select * from filter_id(); --> This is a generic function used in 
> many functions.
> 
> 
> return query
> as select a.*
> from tb3 a inner join tb4 inner join tb 5 inner join #TEMP2;
> end;
> 
> 
> Is there any alternate way of achieving this? Passing multiple records 
> to a function im creating a temp table before invoking the function.
> For receiving an output of multiple rows i'm creating a temp table to 
> reuse further in the code.
> 
> Can this be done using Refcursor? Is it possible to convert refcursor to 
> a temp table and use it as normal  table in query?
> 
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com

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  Cc: adrian.klaver@aklaver.com, rajin89@gmail.com, pgsql-hackers@postgresql.org, pgsql-general@postgresql.org
  Subject: Re: Alternate methods for multiple rows input/output to a function.
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