Re: Changed SRF in targetlist handling

On 05/23/2016 02:37 PM, David G. Johnston wrote:
> ​But then I don't get Joe's point - if its an implementation detail why
> should it matter if rewriting the SRF-in-tlist to be laterals changes
> execution from a serial to an interleaved​ implementation.  Plus, Joe's
> claim: "the capability to pipeline results is still only available in
> the target list", and yours above are at odds since you claim the
> rewritten behavior is the same today.  Is there a disconnect in
> knowledge or are you talking about different things?

Unless there have been recent changes which I missed, ValuePerCall SRFs
are still run to completion in one go, when executed in the FROM clause,
but they project one-row-at-a-time in the target list. If your SRF
returns many-many rows, the problem with the former case is that the
entire thing has to be materialized in memory.

Joe

--
Crunchy Data - http://crunchydata.com
PostgreSQL Support for Secure Enterprises
Consulting, Training, & Open Source Development