Re: tuplestore API problem

Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com> writes:
> 2009/3/27 Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>:
>> 2009/3/27 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
>>> A brute-force solution is to change tuplestore_gettupleslot() so that it
>>> always copies the tuple, but this would be wasted cycles for most uses
>>> of tuplestores. I'm thinking of changing tuplestore_gettupleslot's API
>>> to add a bool parameter specifying whether the caller wants to force
>>> a copy.

> Here's the patch. Hope there are no more on the same reason. It seems
> that we'd need to implement something like garbage collector in
> tuplestore, marking and tracing each row references, if the complete
> solution is required.

I don't like this; I'm planning to go with the aforementioned API
change instead. The way you have it guarantees an extra copy cycle
even when tuplestore is already making a copy internally; and it doesn't
help if we find similar problems elsewhere. (While I'm making the
API change I'll take a close look at each call site to see if it has
any similar risk.)

regards, tom lane