Re: libpq performance issue

> I submitted the appended bug report two days ago, and I resubmit it
> because I do not see it in the mailing lists yet, and I feel that
> the problem constitutes a significant performance issue.
>
> In short, I see 20.3 gigabytes of data memmove()'ed (needlessly in
> this case, which is almost irrelevant) by the pqReadData function
> in the libpq library while retrieving 13 megabytes from the backend.
> It appears to me that the memmove is moving data from and to the
> same memory locations ~1500 times incrementing the number of bytes
> moved by 8K each time.
>
> I tried skipping the memmove when the conn->inStart == 0
> and found that the output sequence is identical to when it is not
> skipped, as I expected.

So you suggesting the following patch, right? Seems safe enough, and I
can imagine memmove not checking if src and dest are the same.

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