Re: Why we have tuplestore and tuplesort?

2009/8/16 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com> writes:
>> Looking for git/cvs log a bit, tuplesort was already there since 1999
>> while tuplestore was introduced around 2000 for materialized node. Why
>> then was tuplestore invented as a new feature instead of extending
>> tuplesort? Can't we unit them now?
>
> I think they'd be unmaintainable if merged.  Each one is complicated
> enough as-is, and they have different concerns and different use-cases
> to optimize for.  Moreover it's not clear that merging them would buy us
> much --- saving one copy step doesn't excite me, even if it actually
> came out to be true which I'm unconvinced about.
>
>                        regards, tom lane
>

I agree it would be unmaintainable. However it sounds like there's no
crystal clear reason the two are separated. Before tuplestore got
multiple read pointers it was quite similar to tuplestore except
performing sort so I can imagine allowing tuplesort to have multiple
read pointers.

Regards,

--
Hitoshi Harada