Re: Reduce build times of pg_trgm GIN indexes

On Wed, 2 Sept 2026 at 11:16, David Geier <geidav(dot)pg(at)gmail(dot)com> wrote:
>
> Hi!
>
> > Thanks for this—looks like a good improvement.
>
> Thanks for reviewing the patch. Attached is v9 with all reviewing
> comments from below addressed.

Please add commit descriptions; the current patches don't have much
other than their subjects which don't describe any rationale for the
changes applied.

0001: LGTM
0002:
1. radix_sort_trigrams_signed has an `int count` argument, but the
caller trigram_qsort uses size_t.

2. This increases the memory requirements of trigram_qsort by a huge margin.
Could you change the radixsort to operate in-place, so that the new
buffer is not needed?

3. The implementation for trigram_qsort_unsigned has not been adjusted
nor replaced, and so keeps the same old performance that
trigram_qsort_signed had.
Please make sure to also adjust that implementation.

0003:

1. ginInsertBAEntry leaks the copied key Datum if the type is by-ref
and already present in the accumulator.

I think specifying HASH_KEYCOPY to only copying the Datum key if an
entry is already present is more appropriate.

2. The comment for ginInsertBAEntries was completely removed, rather
than updated to the new workings.

Kind regards,

Matthias van de Meent
Databricks (https://www.databricks.com)