Re: final patch - plpgsql: for-in-array

On Thu, Nov 18, 2010 at 1:03 PM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
> 2010/11/18 Robert Haas <robertmhaas@gmail.com>:
>> On Thu, Nov 18, 2010 at 12:36 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> I would *much* rather we get the performance benefit by internal
>>> optimization, and forego inventing syntax.
>>
>> +1.
>
> any optimization will be about 10-20% slower than direct access. See
> my tests: on large arrays isn't significant if you use a simple
> expression or full query. This is just overhead from building a
> "tuplestore" and access to data via cursor. And you cannot to change a
> SRF functions to returns just array. I would to see any optimization
> on this level, but I think so it's unreal expecting.

How can you possibly make a general statement like that?  What's slow
is not the syntax; it's what the syntax is making happen under the
hood.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company