Re: Status report on writeable CTEs

On Tue, Jul 20, 2010 at 5:13 PM, Merlin Moncure <mmoncure(at)gmail(dot)com> wrote:
>>>> 2. Use temp table instead of tuplestore list. Since we agreed we need
>>>> to execute each plan one by one starting and shutting down executor,
>>>> it now looks very simple strategy.
>>>
>>> I didn't look at this because I thought using a "tuplestore receiver" in the
>>> portal logic was simple enough.  Any thoughts on how this would work?
>>
>> It's just deconstructing queries like:
>>
>> WITH t AS (INSERT INTO x ... RETURING *)
>> SELECT * FROM t;
>>
>> to
>>
>> CREATE TEMP TABLE t AS INSERT INTO x ... RETURING *;
>> SELECT * FROM t;
>
> Is it acceptable for a wCTE query to manipulate the system catalogs?
> Couldn't this cause performance issues in some cases?

Yeah, I suspect the performance wouldn't be too hot. I think the idea
of writing into a tuplestore and then reading back out from it is the
way to go.

--
Robert Haas
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