From: | Marc Mamin <M(dot)Mamin(at)intershop(dot)de> |
---|---|
To: | "'Pavel Stehule'" <pavel(dot)stehule(at)gmail(dot)com> |
Cc: | "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Fetching from psql procedures |
Date: | 2015-11-20 08:14:46 |
Message-ID: | B6F6FD62F2624C4C9916AC0175D56D88420B59C2@jenmbs01.ad.intershop.net |
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Thread: | |
Lists: | pgsql-general |
>> Hi,
>>
>> I'm looking for a way to build large xml documents based on a set of tables, hence using recursive queries.
>>
>>
>> something like:
>>
>> FOR rec1 IN ...
>> FOR rec2 IN ...
>>
>> RETURN QUERY select '<foo>>
>> FOR rec3 IN ...
>>
>> RETURN QUERY select (XMLELEMENT (...))::text
>>
>> END LOOP;
>> RETURN QUERY select '</foo>>
>>
>> END LOOP;
>> END LOOP;
>>
>>
>>
>> but if I wrap this in a function, it seems that I won't get a result before the whole document is prepared.
>>
>> Is there any way to stream the result as it get produced ?
>> or does anybody knows of a good tutotial for a task like this ?
>
> you can try CTE Common Table Expression. It isn't possible with plpgsql :(
> Theoretically you can write C extension where SRF function can returns data continually.But plpgsql function using local stack and returns data as block.
> Regards
> Pavel
Thanks.
A simpler solution will be to store the result in a temp table and then call a second query to stream it out.
regards,
Marc Mamin
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