Re: nbtree: Cache operator family OID in _bt_setup_array_cmp

On Jan 7, 2026, at 22:45, Peter Eisentraut <peter@eisentraut.org> wrote:

On 31.12.25 11:13, Chao Li wrote:

On Dec 31, 2025, at 18:04, Kirill Reshke <reshkekirill@gmail.com> wrote:

On Wed, 31 Dec 2025 at 13:16, Chao Li <li.evan.chao@gmail.com> wrote:

Hi Hackers,

While reviewing a separate patch related to nbtree, I noticed that _bt_setup_array_cmp in nbtpreprocesskeys.c performs multiple redundant lookups of the operator family OID via rel->rd_opfamily[skey->sk_attno - 1].

The attached patch caches this value in a local opfamily variable. This matches the pattern used in several other functions within the same file (such as _bt_skiparray_strat_decrement, _bt_preprocess_array_keys, etc.), making the code more consistent and readable.

The assignment is placed after the early-return check for (elemtype == opcintype) to ensure we only perform the array indexing when the cross-type comparison logic is actually reached.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/

Hi!
We do not cache anything here, this is just a refactoring for nbtree internals?

Yes, just cache  rel->rd_opfamily[skey->sk_attno - 1] into a local variable.

But that's not caching, at least in a compiled language with an optimizing compiler.

Are you claiming that this has a performance impact, or that it makes the code easier to understand, or something else?  The patch isn't necessarily wrong, but a clear description of the motivation would be good.