Possible typo in nodeAgg.c

On Fri, Oct 16, 2020 at 09:03:52AM +0000, Hou, Zhijie wrote:

Hi

In /src/backend/executor/nodeAgg.c

I found the following comment still use work mem,
Since hash_mem has been introduced, Is it more accurate to use hash_mem here ?

@@ -1827,7 +1827,7 @@ hash_agg_set_limits(double hashentrysize, double input_groups, int used_bits,
/*
* Don't set the limit below 3/4 of hash_mem. In that case, we are at the
* minimum number of partitions, so we aren't going to dramatically exceed
-	 * work mem anyway.
+	 * hash_mem anyway.

Can someone comment on this? Is the text change correct?

--
Bruce Momjian <bruce@momjian.us> https://momjian.us
EDB https://enterprisedb.com

Only you can decide what is important to you.

On Fri, 3 Nov 2023 at 13:49, Bruce Momjian <bruce@momjian.us> wrote:

On Fri, Oct 16, 2020 at 09:03:52AM +0000, Hou, Zhijie wrote:

/*
* Don't set the limit below 3/4 of hash_mem. In that case, we are at the
* minimum number of partitions, so we aren't going to dramatically exceed
- * work mem anyway.
+ * hash_mem anyway.

Can someone comment on this? Is the text change correct?

"work mem" is incorrect. I'd prefer it if we didn't talk about
hash_mem as if it were a thing. It's work_mem * hash_mem_multiplier.
Because of the underscore, using "hash_mem" to mean this makes it look
like we're talking about a variable by that name. Maybe it would be
better to refer to the variable name that's used to store the result
of get_hash_memory_limit(), i.e. hash_mem_limit. "the limit" should
likely use "*mem_limit" instead as there are multiple limits
mentioned.

It would also be better if this comment explained what's special about
4 * partition_mem. It seems to have nothing to do with the 3/4
mentioned in the comment.

David