Re: Fix incorrect comments in tuplesort.c

David G. Johnston <david.g.johnston@gmail.com>

From: "David G. Johnston" <david.g.johnston@gmail.com>
To: David Rowley <dgrowleyml@gmail.com>
Cc: cca5507 <cca5507@qq.com>, Chao Li <li.evan.chao@gmail.com>, pgsql-hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-12-07T23:10:00Z
Lists: pgsql-hackers
On Sun, Dec 7, 2025 at 3:09 PM David Rowley <dgrowleyml@gmail.com> wrote:

> The comment is effectively
> explaining that we don't want to make the array big enough so that a
> malloc will always be required.


Doesn't what you are saying contradict both the formula (the +1
post-division) and the comments:

/*
* Initial size of array must be more than ALLOCSET_SEPARATE_THRESHOLD;
* see comments in grow_memtuples().
*/
state->memtupsize = INITIAL_MEMTUPSIZE;
state->memtuples = NULL;

and in grow_memtuples:

* That shouldn't happen because we chose the
* initial array size large enough to ensure that palloc will be treating
* both old and new arrays as separate chunks.

?

David J.