v20240413-0001-Update-nbits_set-in-brin_bloom_union.patch

From 450f992c12d43c14aa1b4b72cfd9d3ce0251eed1 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tv@fuzzy.cz>
Date: Sat, 13 Apr 2024 22:15:26 +0200
Subject: [PATCH v20240413 1/4] Update nbits_set in brin_bloom_union

When merging BRIN bloom summaries, it's not enough to merge the bitmaps,
we need to update the nbits_set counter too.

This is mostly harmless, as it does not affect correctness - as the
counter is used only in the out function, and that's used only in
pageinspect to show basic info about the summary.

Backpatch-through: 14
---
 src/backend/access/brin/brin_bloom.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/backend/access/brin/brin_bloom.c b/src/backend/access/brin/brin_bloom.c
index ebf33016279..9e3bc567303 100644
--- a/src/backend/access/brin/brin_bloom.c
+++ b/src/backend/access/brin/brin_bloom.c
@@ -687,10 +687,20 @@ brin_bloom_union(PG_FUNCTION_ARGS)
 
 	nbytes = (filter_a->nbits) / 8;
 
+	filter_a->nbits_set = 0;
+
 	/* simply OR the bitmaps */
 	for (i = 0; i < nbytes; i++)
+	{
 		filter_a->data[i] |= filter_b->data[i];
 
+		for (int bit = 0; bit < 8; bit++)
+		{
+			if (filter_a->data[i] & (0x01 << bit))
+				filter_a->nbits_set++;
+		}
+	}
+
 	PG_RETURN_VOID();
 }
 
-- 
2.44.0