Message-ID: <54807016.8010904@2ndquadrant.com>
Date: Thu, 04 Dec 2014 22:30:46 +0800
From: Craig Ringer <craig@2ndquadrant.com>
Organization: 2nd Quadrant
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To: Heikki Linnakangas <hlinnakangas@vmware.com>,
 Matt Newell <newellm@blur.com>, pgsql-hackers@postgresql.org
Subject: Re: libpq pipelining
References: <2059418.jZQvL3lH90@obsidian> <54802498.7020704@vmware.com>
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On 12/04/2014 05:08 PM, Heikki Linnakangas wrote:
>>
> 
> A good API is crucial for this. It should make it easy to write an
> application that does pipelining, and to handle all the error conditions
> in a predictable way. I'd suggest that you write the documentation
> first, before writing any code, so that we can discuss the API. It
> doesn't have to be in SGML format yet, a plain-text description of the
> API will do.

I strongly agree.

Applications need to be able to reliably predict what will happen if
there's an error in the middle of a pipeline.

Consideration of implicit transactions (autocommit), the whole pipeline
being one transaction, or multiple transactions is needed.

Apps need to be able to wait for the result of a query partway through a
pipeline, e.g. scheduling four queries, then waiting for the result of
the 2nd.

There are probably plenty of other wrinkly bits to think about.

-- 
 Craig Ringer                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


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